Text preview for : CPD-G400.pdf part of SONY CPD-G400 Training Manual for CPD-G400



Back to : CPD-G400.pdf | Home

S

®

Training Manual

Computer Monitor
F99 Chassis CPD-G400

Circuit Description and Troubleshooting Course: MON-04

Sony Service Company A Division of Sony Electronics Inc ©1999 All Rights Reserved Printed in U.S.A.

S is a trademark of Sony Electronics

Circuit Description and Troubleshooting:
Model:
CPD-G400/F99 Chassis

Prepared by: National Training Department Sony Service Company A Division of Sony Electronics Inc. Course presented by _____________________________________ Date___________________________________________________ Student Name ___________________________________________

S
SEL Service Company A Division of Sony Electronics Inc. 1 Sony Drive Park Ridge, New Jersey 07656

MON040200

Printed in U.S.A.

Table of Contents
Sony Monitor Model CPD-G400 Specifications 1 Normal Operation / Features
Power ON Power OFF Aging Mode Lock control S RGB Customer Convergence Moire Adjustment Reset All User Adjustments Reset Just One User Adjustment Self Diagnostic Function AC Input Degaussing Circuit Surge Protection Circuit Operating Voltages and Resistances 17 17 19 19

3
3 3 3 4 4 4 4 4 4 4

Switching Oscillator
Start Up - Normal Mode Active off Mode Light Mode Mode Switching Operating Voltages Switching Oscillator Part Functions

21
21 23 23 25 25 29

Low Voltage Regulating Circuit
T602 Feedback The Regulator Circuit Measured Voltages Simulated Defects and Symptoms

31
31 31 33 35

Overall Block
Power Supply Deflection High Voltage Video Processing

5
5 5 7 7

Video Block Input Video Output G2 Control
CRT Brightness G2 Circuit

37 39 41 47
47 47

Power Saving Modes
Power Mode Summary Power Mode Circuit Activity

9
9 11

Power Supply Block Degaussing/Surge Protection

13 17

Circuit Voltages

47

Appendix
Power MOSFET Tests IIC or I2C Bus
Data Format

Sync / Deflection Block
CPU IC1001 & DPU IC801

49
49

i ii
ii

Horiz / Vert Oscillator Vertical Output Horizontal Output High Voltage
HV Manufacture HV Regulation Protection Troubleshooting

51 53 55 57
57 57 59 59

Plug and Play Monitor Problems Checklist LCD Concept Service Position
NO High Voltage Testing Position Full Operational Testing Position

iii v vii viii
viii ix

Dynamic Focus Concept
Static Focus Dynamic Focus

61
61 61

Dynamic Focus Circuit
Horizontal Dynamic Focus Correction Vertical Dynamic Focus Circuit

63
63 63

Digital Convergence Self Diagnostic Function

65 67

1

Sony Monitor Model CDP-G400 Specifications
Trinitron Picture Tube
0.24 mm aperture grill (fine) pitch 19 inches measured diagonally 90 degree deflection (low distortion)

Power Saving

4 Power Modes (3 power saving): Normal ­ 140Watts Standby ­ 15 Watts Suspend (Sleep) ­ 15 Watts Active Off ­ 6 Watts

Viewable Area Standard Image Area Maximum Resolution Deflection Frequency AC Input

14 3/8" x 10 7/8 " (18" viewable image)

Circuit Protection
13 7/8" x 10 ˝"

+200V Flyback Voltage Vertical Output Automatic Beam Current Limiting (ABL)

1800 dots = Horizontal 1024 dots = Vertical

* Plug and Play Abbreviations
30 to 107 kHz = Horizontal 48 to 120Hz = Vertical

Level DDC1

Name Display Data Channel Uni-directional data @ V sync intervals Display Data Channel Bi-directional data Display Data Channel Bi-directional data

Communications PC reads monitor EDID operational info. Protocol V. Sync PC reads/writes monitor EDID operational info. Protocol IIC Bus PC reads/writes monitor EDID operational info. And adjustment data. Protocol Access Bus

120V AC; 50/60 Hz 140W (1.17amps) 6 Amps initial surge (measured)

DDC2B

DDC2Bi

Operating Temp Mass Plug and Play

10 to 40 degrees C

57 lbs. 5 oz.

DDC1 / DDC2B / DDDC2Bi / GTF*

NOTES

2

3

Normal Operation / Features
Power ON
Initial Conditions: No video input. 120Vac input. Cold start. 1. Press power ON switch. 2. Front panel indicator LED is green. 3. Degassing coil receives AC current, causing the picture tube's aperture grill to vibrate (humming sound). 4. The AC surge current is about 6 AC amps. 5. Current drops down to 0.6 AC amps. 6. The following black lettered graphic appears at the center of the screen with strips of the color indicted:
INFORMATION NO INPUT SIGNAL INPUT 1 WHITE RED GREEN BLUE

Note: During testing you may return from the Active Off Mode without an input by pressing any front panel button. As the monitor powers up, it is normal for the power supply's oscillator to run at one of two frequencies. The oscillator may run at the lower oscillator frequency of 21kHz instead of the full power mode of 65kHz. It will sense an increase in load and switch automatically when necessary.

Power OFF
Initial conditions: Unit is in standby mode. No video input. 1. Press the power OFF button. 2. The orange LED goes dark after three seconds.

Aging Mode
This mode is commonly found in Sony monitors and warms up the CRT in preparation for the technician to perform color temperature adjustments. By pressing a series of front panel buttons (different for each model), this mode can be activated. The CPU detects this button combination and places a DC bias on the CRT cathodes to produce a white screen. The procedure in the CPD-G400 is as follows: 1. Disconnect the video cable from the computer or shut off the computer so there is no sync input the monitor. 2. Press the monitor switch in. A no video-input message will appear on the screen when the CRT warms up. 3. Move the ball type control button to the left and hold it there for two seconds. This must be done before the monitor goes into the Active Off Low Power Mode (two minutes after power ON). 4. The entire screen will turn white and the power indicator will alternately blink green and orange. This is the aging mode. 5. The monitor will exit from the aging mode if: · The control button is moved to the right and held for two seconds. · Input sync is detected (computer turned on). · The input switch is changed. · The power button is pressed again (off).

Active Off Low Power Mode (no input)
1. Two minutes after pressing the power ON switch, the monitor automatically enters the standby mode when there is no input signal detected. The monitor shuts down and the graphic disappears into a dark screen. 2. The front panel indicator LED changes from green to orange. 3. Activating any front panel user function will return the monitor to the ON mode where the graphic will reappear. The front panel functions are: · Input switch (input 1 or 2) · Menu control ­ Any direction (up, in, outward, left, right) · Reset button

Image Restoration
This circuit is operated by the customer to automatically white balance the picture. This is achieved by adjusting the RGB drive (signal) levels to compensate for reduced cathode emission. At the factory, the "Ik" voltages corresponding to each RGB cathode current are stored into memory. When this circuit is activated from the menu, the screen turns white for one second as the gain of the R, G or/and B drive levels are increased. When the measured Ik voltages are matched to the ones in memory, the operation is complete and the new drive levels are stored. The circuit details are in the Video Output text where the Image Restoration circuit resides.

Moiré Adjustment
When fine lines are viewed though other fine lines, additional patterns are developed when the lines do not coincide. For example if you were looking at a window blind through a box fan (with a grill), some lines would not be visible and others would appear distorted. This is the Moiré effect. In a monitor it corresponds to picture lines presented on a vertical slotted CRT internal aperture grill. The Moiré adjustment affects high frequency video response.

Reset All User Adjustments
You can reset all user adjustments by pressing and holding the front panel RESET button in for two seconds when there is NO menu displayed on the screen. All menu customer settings are then reset to default levels except: · The menu language · The menu position · The Control Lock function if it was ON. The reset button does not work when the lock is ON.

Lock Control
All customer functions can be inhibited from the Option menu except the front panel Input and Power switches. This is used to prevent children from resetting all your monitor settings.

S RGB
This is a preset industry standard color setting used with information from the internet and with a sRGB compliant printer. When a sRGB standard color object is indicated on the internet, you may view it in that true color by selecting sRGB from the menu's color group. If you have a sRGB printer you may print the object at that color too. The sRGB setting just fixes the brightness and color levels to pre-established settings.

Reset Just One User Adjustment
Entering the menu setting you wish to reset with the control button and pressing the RESET button does this.

Self Diagnostic Function
The front panel orange/green LED is used to determine what section caused the monitor to enter the protection state. This is explained in the Self-Diagnostic Function section of this book.

Customer Convergence
The customer can move the red and blue centering adjustments from the menu. This can be done in the horizontal and vertical plane.

4

5

Overall Block
The overall block diagram shows the major sections of the Sony model CPD-G400 monitor that house a F99 chassis. The following blocks are listed by operational importance: · · · · Power Supply Deflection High Voltage Video Processing

Deflection
The deflection block consists mainly of the oscillator, the vertical and the horizontal deflection stages. These stages generate the signal required to make the magnetic field in order to move the electron beams across the screen.
Main Deflection Blocks Stage Oscillator Parts IC1001 Function · Make horizontal and vertical signals at a default frequency. · Matches its oscillator frequency to the computer s sync signal when input. Vertical Deflection IC801 IC401 Vert D Yoke IC801 Q501-Q504 · · · · Shape the oscillator pulse into a ramp waveform. Amplify the vertical ramp to drive the yoke coil. Shapes the oscillator signal into the correct width. Amplifies the signal to drive the horizontal yoke coil.

Power Supply
The power supply block consists of the voltage generating and regulating power supply and the managing CPU IC1001. The power supply delivers standby +5V to the CPU to keep it alive. In turn, CPU IC1001 uses two outputs to select the power supply's operating modes. The mode decided by the CPU is based upon the input sync and protection circuit (Protect 1-3) signals.
CPU Power Supply Control Lines Output Heater Purpose Shuts off CRT filaments and enters Active Off low power burst Mode. Switches the +5V and +12V OFF. · · Modes used Active Off (no H & V sync input) Protection (latched in the Active Off Mode) Standby (no H sync input) Suspended (no V sync input) Active OFF (no H & V sync input) Protection (latched in the Active Off Mode)

Horizontal Deflection

Stages that support Vertical and Horizontal Deflection are the dynamic focus, pincushion, and convergence stages. These stages ensure that the beam is uniformly focused, fills the entire screen and that all three beams land at the right place on the screen.

Remote On/Off

· · · ·

15M RGB 1 IC008 INPUT SEL. RGB IC001 RGB PRE-AMP

G2 CONTROL RGB G2 IC002 RGB OUT RGB CRT

RGB 2 2 1

S2001 IC009 SYNC SEL. SW.

OSD RGB

BLK

RGB BKG IC004 RGB CUT-OFF CONT. A BD.

FOCUS

HV

15M A BD. D BD.

H+V SYNC 2

IC003 OSD 11C DATA/CLK

Ik

H+V SYNC STBY +5V

GRN/ORG D FOCUS IC1001 CPU PROTECT 1-3

D BD. T901 FBT

OFF ON

IC1603, Q605 POWER SUPPLY

HEATER REMOTE ON/OFF V+F SYNCO H+V DF

IC901, Q902 HV OUTPUT

+200V +80V +15V -15V +12V N BD. +5V IC801 DPU (N BD.) HD E/W VSAWIN PROTECT 3 IC1001

Q501-Q503 H DRIVE

Q504 H OUT

PROTECT 1,2 IC1001 H D YOKE

PINCUSHION IC401 V OUT IC701, IC702 CY AMPS VD YOKE CONV. YOKE
16MON04 1220 1/19/00

OVERALL BLOCK 6

7
Deflection Support Stages Stage Dynamic Focus Parts IC1001 IC801 Q701-5, IC503, Q706. Pincushion IC1001 IC801 Q506, Q508-9 Convergence IC1001 IC801 IC701 IC702 Function Oscillator signal for beam location Signal shaping Horizontal dynamic focus amp. Vertical dynamic focus amp. Oscillator signal for beam location Signal shaping Amplifier and output driver Oscillator signal for beam location Signal shaping Static convergence amplifier Dynamic convergence amplifier RGB Amp Output OSD Stage Input Switch Parts IC008 IC009 IC001 IC002 IC1001 IC003 RGB input switch Sync input switch Preamp of the input signal Higher voltage amplifier Selects OSD pattern based upon user selection Generates the OSD picture/graphic Video Processing Block Function

DAS Control
An external alignment computer controls many parts of the monitor's alignment. The alignment is achieved using a special computer to monitor communications connection on the D board. The 4 pin internal jack connects to the monitor's CPU IC1001. · TXD ­ Transmits signal to DAS computer · RXD ­ Receives signal from the DAS computer · Stby +5V ­ Monitors power - Present when the monitor is ON. · Gnd ­ Common ground. A computer loaded with DAS software permits monitor adjustments by changing the data stored in memory (IC005 not shown) via CPU IC1001. The DAS software will permit the technician to change this memory data which affects these stages:
DAS Control via CPU IC1001 Adjustment CRT background and G2 level H & V Position (centering) H & V Size Pincushion Convergence IC001 IC001 IC801 Video signal positioning Deflection size Circuits used

High Voltage
The high voltage block uses a flyback transformer and some of the later horizontal deflection circuits. This block's primary purpose is to develop and maintain the high voltage for the final beam acceleration across the picture tube bell. Two additional high voltages are also made from the flyback T901. The static focus voltage is used for focus at the center of the screen and the G2 voltage is necessary to accelerate the beam after the focus grid slows down the electrons.

Video Processing
The video-processing block consists of an input switch, amplifier and output stage. An on screen display IC003 is added to provide visual feedback about the monitor functions and features.

IC801, Pin Output transistors IC801, Conv Outputs

15M RGB 1 IC008 INPUT SEL. RGB IC001 RGB PRE-AMP

G2 CONTROL RGB G2 IC002 RGB OUT RGB CRT

RGB 2 2 1

S2001 IC009 SYNC SEL. SW.

OSD RGB

BLK

RGB BKG IC004 RGB CUT-OFF CONT. A BD.

FOCUS

HV

15M A BD. D BD.

H+V SYNC 2

IC003 OSD 11C DATA/CLK

Ik

H+V SYNC STBY +5V

GRN/ORG D FOCUS IC1001 CPU PROTECT 1-3

D BD. T901 FBT

OFF ON

IC1603, Q605 POWER SUPPLY

HEATER REMOTE ON/OFF V+F SYNCO H+V DF

IC901, Q902 HV OUTPUT

+200V +80V +15V -15V +12V N BD. +5V IC801 DPU (N BD.) HD E/W VSAWIN PROTECT 3 IC1001

Q501-Q503 H DRIVE

Q504 H OUT

PROTECT 1,2 IC1001 H D YOKE

PINCUSHION IC401 V OUT IC701, IC702 CY AMPS VD YOKE CONV. YOKE
16MON04 1220 1/19/00

OVERALL BLOCK 8

9

Power Saving Modes
This monitor has four power modes. The CPU monitors video input sync to select the monitor's power mode of operation.

the orange LED to also turn ON. Both LED on means the monitor is in the Suspended Power Mode.

Active OFF Power Mode
A loss of both horizontal and vertical sync causes the monitor to enter a very low power consumption mode. The CPU responds to no sync by placing the outputs at IC1001/pins 7 and 8 LOW. The LOW from pin 7 shuts off the 5 and 12 volt supply lines to the monitor causing blanking as in the previous standby and suspended modes. When IC1001/pin 8 goes LOW, the power supply enters the burst mode of operation. In this mode the power supply is only powered up in bursts. As a result, all the monitor supply voltages are Low or absent depending upon the severity of the load. There is sufficient energy to power standby regulator IC609 (not shown) to the CPU. This is because the CPU needs little current, so the standby 5V is normal while the remaining voltages to the monitor are extremely low. In this Active Off power mode, the green and orange LEDs are both ON as in the suspended power mode. The difference is that in the Active OFF mode, the +15 from the power supply is no longer active and the surge relay can be heard de-energizing as it enters this mode.

Normal Operation
When CPU IC1001/pins 20 and 30 detects both vertical and horizontal sync or Sync On Green is detected at IC1001/pin 28, the power supply operates normally and the monitor is unblanked. The front panel combination orange/green LED only lights green.

Standby Power Mode
When there is only a loss of horizontal sync at IC1001/pin 30, the monitor shuts down some of its circuitry. CPU IC1000/pin 7 goes LOW, shutting off the +5V supply line to the monitor. At the same time IC1001/pin 52 causes the orange LED to blink continuously while the green LED remains ON.

Suspended Power Mode
When Vertical sync is lost at IC1001/pin 20, the monitor shuts down some of its circuitry. CPU IC1001/pin 7 goes LOW, shutting off the +5V supply line to the monitor, just as above. At the same time IC1001/pin 52 causes

Power Mode Summary
Six seconds after the monitor is powered ON, the degaussing circuit relay de-energizes. A display then appears showing the video-input status. After one minute the monitor will enter one of four power modes if sync is missing. The CPU monitors video input sync to implement the power mode.
Monitor Power Modes Power Mode 1. Normal 2. Standby (115 ac mA.) 3. Suspend (115 ac mA.) 4. Active Off (52 ac mA.) No Vertical sync No Vertical or Horizontal Sync ON ON ON ON None Surge relay de-energizes 60 seconds after pressing the power ON switch. Cause H and V sync input to the monitor No Horizontal sync Green LED Indicator ON ON Orange LED Indicator OFF Blinks Audible Indicator Surge relay energizes one second after pressing the power ON button. None

OFF ON BURST MODE INPUT 1/2 SEL SW. S2001 ORG. D2001 GRN. FROM INPUT 1 H1 V1 G1 H IC009 INPUT SYNC SW. V
30 20 28 52 51

POWER SUPPLY 5V/12V REG. REG IC HEATER
8 7

REMOTE ON/OFF

LED 2 LED 1 IC1001 CPU

STBY 5V

FROM INPUT 2

H2 V2 G2

SOG

STANDBY 5V

POWER SAVING CIRCUIT 10

5MON04 1205

1/19/00

11

Power Mode Circuit Activity
The front panel combination green/orange LED identifies the lack of H or V sync input. The monitor power operating modes relating to the circuitry is summarized this chart:

Monitor Mode Details
Power Mode after one minute 1. Normal Power Indicators * Green ON AC Power Consumption * 140W (1.16A.) Nominal. Surge to 6 amps. 15W (0.115 A. measured) 15W (0.115 A. measured) 3W (0.052 A. measured) Video Blanking Unblanked Main Power Supply Active CRT Heater IC610 Active Surge Resistor Bypass Relay RY602 Relay energized. Resistor bypassed. Relay energized. Resistor bypassed. Relay energized. Resistor bypassed. Relay OFF 5V Regulator IC605 Regulator ON Regulator OFF Regulator OFF Regulator OFF Standby 5V IC609 Active IC1001 CPU input H & V input sync. No H sync input. No Vertical Sync input. No Vertical or Horizontal Sync.

2. Standby

Green = ON Orange = blinks Green = ON Orange = ON Green = ON Orange = ON

Blanked

Active

Active

Active

3. Suspend

Blanked

Active

Active

Active

4. Active Off

Blanked

Bursts only

OFF

Active

+15V SURGE RELAY RY602 D2001 ORG GRN LED 1 FROM SYNC SEL SW IC009 H SYNC V SYNC C SYNC (SOG) 30 20 28 CPU IC1001 CDX9523S 51 52 31 11 D616 SCR Q606 INV 8 7 B+ HV DET DET 14 16 37 ABL 17 37 11C CLK D921 - 5.6V D1003 - 5.6V D1001 5.6V 11C DATA SDA SCL 3 4 HEATER 2 IC610 +5V REG 1 4 HEATER VOLTAGE REMOTE ON/OFF IC001 RGB PRE-AMP D912 16V R660 VFBP (3.3V) VOUT IC401/7 R656 +200V R417 470k D405 R661 RGB OUTPUT IC002 ABL FBT T901/11 FBT T901/8 D911 LED 2 STBY +5V POWER SUPPLY BURST MODE D619 D621 +200V D620 IC609 +5V REG 2 4 IC605 +5V REG 1 STBY +5V

+5V

+

42 C409 D402 5.6V

R919

SELF DIAGNOSTIC BLOCK 12

4MON04 1203 1/19/00

13

Power Supply Block
The power supply develops various voltages required by the monitor. The CPU works with the switching power supply to enter a very low (energy star compliant) power saving mode when the external computer is turned Off but the monitor switch is still ON. The CPU also activates this same power saving mode when a circuit failure occurs. The monitor has several major power supply sections:
Power Supply Sections Sections Degaussing Circuit Surge Protection Circuit (Q607) Function Demagnetizes the picture tube at power ON. Prevents a momentary short circuit to the AC line at power ON. Reduces voltage fluctuations at power ON. Switching Power Supply (IC603, Q605, T602) H Centering Control (IC502, Q519) Shunt & Stby Regulation IC608, Q609) CPU Control (IC1001) Develops multiple voltages needed by he monitor. Centers the picture by adding a DC voltage onto the H yoke winding. Sets the switching power supply pulse width to maintain a stable power supply output voltage. Switches the power supply into one of four power modes: 1. Normal All voltages are operational 2. Standby - +5V & +12V regulators = OFF, screen blanked. ( No H sync input) 3. Suspend - +5V & +12V regulators = OFF, screen blanked. (No V sync input) 4. Active Off All power supply voltages very low except standby +5V to CPU. (No H & V sync). Heater Regulator Regulated voltage to CRT filaments. Switched Off in the Active Off Mode.

Power Supply Output
This power supply has outputs that are fused and unfused:
Fused Switching Power Supply Outputs Voltage + 6.5V -15V Fusible Resistor R649, R650 R648 Destination Horiz. Centering H Drive Q504, Rotation Drive IC703, Vert. Out IC401, Converge Amp IC701, IC702, 12V Regulator IC604, Surge relay RY602, Rotation Drive IC703, Vert. Out IC401, Converge Amp IC701, IC702, Heater Regulator IC610, Sw +5V Reg. IC605, Standby Reg. IC609, Stby Reg. Circuit Q609.

+15V

R645

+8V

R647

Unfused Switching Power Supply O utputs Voltage +200V Destination Active O ff Switch D616, RGB Cutoff Control IC004, Pin Out Q 506, HV Regulator Q 901, CPU IC1001/pin 14. RG B Output Q 704/5, IC002, Dynam ic Focus Circuit

+80V

Active Off, Low Power Mode
When the computer connected to the monitor is shut off, horizontal and vertical sync input signals stop. CPU IC1001 senses this loss and turns off both the Remote ON/OFF and Heater output lines. The Remote ON/ OFF line shuts off the +5 and +12V power lines to the monitor (via IC605 and IC604). The Heater output line turns off the CRT filament voltage (IC610) and at the same time turns ON SCR D616 to activate the Active Off Power mode.

F601 OFF TH600
ON

D625

R649

+ -

IC502, Q519 H.CENT.

DC BIAS TO H.YOKE PWM3 IC1001/4

SURGE CIRCUIT Q607

+15V

R650

+200V DEGAUSS CIRCUIT D. COIL PWM 2 R645 SERIAL DATA IC1003 RESET STBY +5V IC607 ISOLATE SW. IC608 SHUNT REG. IC603, T602, Q605 SWITCHING POWER SUPPLY - 15V R648 +80V R647 IC604 REG. + C628 2,200 IC610 HEATER REG. CRT HEATER (B) CTL IC605 +5V REG.

+12V

+15V

IC1001 CPU PROT.

Q609, STBY REG. CIRCUIT IC609 +5V REG.

+5v

STBY +5V

H,V SYNC FBT VOLT, ABL, 200V, VERT.OUT

+200V

D616 ACTIVE OFF SW.

REMOTE ON/OFF

HEATER ON/OFF

POWER SUPPLY BLOCK 14

2MON04 1197 1/14/00

15
Active Off Mode Entry SCR device D616 starts the Active Off Power Mode. The 200V and 8V lines are connected when D616 turns ON. The increased voltage on the 8V line requires an immediate correction by the switching power supply (IC603). If the 8V line is not restored to 8V within a period of time, the power supply (IC603) enters the Active Off Power Mode. In this mode, the oscillator is only operated for a few cycles in bursts. This reduction in power drops almost all the switching power supply output voltages. The 8V-output line to the CPU (via IC609) requires so little power it can operate in this low power mode with sufficient voltage. Standby regulator circuit (Q609) is used to maintain the standby voltage in this Active Off Power Mode. Active Off Exit When the computer is turned ON, the CPU IC1001 detects sync. To wake up the monitor from the Active Off Mode, CPU IC1001 turns ON the Remote On/Off output. This places a load on the 8V line. The load is sensed by the switching power supply via Q609 (IC603 turns on) the oscillator full time instead of in bursts. This continuous oscillator output provides sufficient power to maintain the 8V line with a full load. Although a failure in any one of these circuits can trigger the Active Off Power Mode, the CPU will indicate the defective circuit using the front panel LED.

Protection
The CPU monitors several sections and enters the Active Off Low Power Mode to drop power for protection. The CPU monitors the following circuits:
Circuits Monitored Circuits HV Regulator Circuit (Excessive Flyback voltage) RGB Cutoff Circuit (Excessive ABL Voltage) Vertical and Horizontal Output LED Indication Both Green and Orange LEDs blink at 1 Hz. Both LEDs blink : ON = 1 sec, OFF = 2 sec. Both LEDs ON = 2 sec. OFF = 1 sec

F601 OFF TH600
ON

D625

R649

+ -

IC502, Q519 H.CENT.

DC BIAS TO H.YOKE PWM3 IC1001/4

SURGE CIRCUIT Q607

+15V

R650

+200V DEGAUSS CIRCUIT D. COIL PWM 2 R645 SERIAL DATA IC1003 RESET STBY +5V IC607 ISOLATE SW. IC608 SHUNT REG. IC603, T602, Q605 SWITCHING POWER SUPPLY - 15V R648 +80V R647 IC604 REG. + C628 2,200 IC610 HEATER REG. CRT HEATER (B) CTL IC605 +5V REG.

+12V

+15V

IC1001 CPU PROT.

Q609, STBY REG. CIRCUIT IC609 +5V REG.

+5v

STBY +5V

H,V SYNC FBT VOLT, ABL, 200V, VERT.OUT

+200V

D616 ACTIVE OFF SW.

REMOTE ON/OFF

HEATER ON/OFF

POWER SUPPLY BLOCK 16

2MON04 1197 1/14/00

17

Degaussing/Surge Protection
AC Input
There are several parts between the AC input and the bridge rectifier D625. The function of these parts are explained in the chart below:
AC Input Parts Part / Name F601 / Input fuse R674 / Resistor LF602 / Choke Function Current limit Bleeder Line noise canceling Possible Symptoms if defective Monitor is dead. Arcing at plug when unplugged from AC. Intermittent noise on monitor screen and/or radio/TV interference. Monitor is dead. Intermittent failure of monitor s power handling parts. Shorted Open fuse

turing (damaging) semiconductors in the monitor. The VDR returns to infinite resistance when the applied voltage disappears. VDRs will not shunt a high-energy pulse from a direct lightning hit on the power line. Hopefully the VDR will short and take out the fuse, saving other parts within the monitor. VDR Testing 1. Measure the resistance across the VDR terminals. A good one will read infinity (open). 2. To ensure the VDR is not open internally, measure its capacitance. The capacitance will vary depending upon the construction and vendor, but none should be open (no capacity) unless bad. The trigger voltage is usually related to the part number that is stamped on the VDR. In this unit, VA601 is stamped 471K (470 Volts) and measures 375pf (out of the circuit). For comparison, a different vendor VDR taken from a TV is stamped 430NR and measures 198pf. 3. Having a capacitance only proves the VDR is not open. It does not prove that it will operate at the trigger voltage. When the monitor's power handling parts periodically fail without cause, the VDR is in doubt. Replace it.

VA601 / VDR * (375pf) C636 & C637 / Capacitors

Clips incoming voltage spikes

Reduces the Constant radio/TV interference amplitude of Repetitive VDR failure incoming/outgo ing noise spikes. Limits the monitor s turn ON surge current Passes AC to monitor Open Shorted Dead set D625 failure

Degaussing Circuit
Purpose Color TV sets and color monitors have electron beams that are targeted to a specific location on the screen. An external magnetic field can move the beam to an undesired location on the screen, changing the desired color near the source of the magnetism. This can occur when a part of the picture tube's metal structure is magnetized in transportation or by placing an unshielded speaker magnet nearby. Applying a strong AC field about the tube at turn ON can demagnetize the tube. This picture tube demagnetizing is called degaussing. Degaussing is characterized by a strong humming noise at power on that only lasts approximately one second. During this second, the picture tube is engulfed with a strong AC field and the AC current consumption is about 6 AC amps. If the magnet is external to the monitor, the undesired color will return. Remove the external magnet.

TH600 / Thermistor (6.5 ohms cold) S601 / ON/Off Switch

Unreliable power ON

VDR VA601 Operation The resistance of a VDR will drop from infinity to a low value (depending upon the construction) when the voltage applied to its terminals exceeds the trigger voltage. This reduction in resistance will reduce a high voltage, but low energy (pulse width), voltage spike and prevent it from punc-

RY601

D628 R675

Q608 DIGITAL TRANSISTOR DEGAUSS PWM2 IC001/5

TH601 1 F601 6.3A AC R674 560k AC VA601 LF602 LFT C636 470pF C637 470pF ON/OFF S601 R604 2.2 OHMS 10W D605 4 R625 0.1 OHM DGC COIL +158V TO IC603/1 SRT T602/9

TH600 + C611 R605 470 2.7 OHMS 10W +15V R671 10k

RY602 R672 150 N R673 + C635 22 Q607 D627 8.2V

SURGE PROT.

DEGAUSSING / SURGE PROTECTION

1MON4 1196

1/19/00 11 29 99

18

19
Circuit Operation Degassing only occurs after the front panel power is pressed. The sequence of operation is as follows: 1. Press the power ON button (not shown). 2. 158V is applied to the power supply stage (not shown). 3. The power supply stage makes standby +5V for the CPU IC1001 and reset IC1003 (not shown). 4. Once the CPU is reset, IC1001/pin 5 outputs a HIGH to activate the degaussing circuit. 5. The CPU HIGH turns on relay driver digital transistor Q608 (has internal resistors to operate with 5V input). 6. Q608 grounds degaussing relay RY601, energizing it. 7. RY601's contacts close passing 120VAC through TH601 to the degaussing coil around the bell of the picture tube. The AC demagnetizes the internal metal parts of the picture tube. 8. Within two seconds TH601 has increased resistance from 4.2 ohms cold to a few 100k ohms hot. 9. In approximately six seconds after the power button was pressed, CPU IC1001 discontinues the HIGH from pin 5 so the degaussing relay contacts open, removing power from the degaussing coil. 10. CPU IC1001/pin 5 will remain LOW as long as there is standby +5V applied to it (power switch is ON). The sequence of operation is as follows: 1. Power ON button is pressed. 2. Heavy current goes to the degaussing circuit. 3. The monitor's power supply is current limited by TH600 (6.5 ohms cold). Although delayed, the power supply voltages come up. 4. +15V is one of the power supply voltages. This voltage is applied to the surge protection circuit at RY602 and C635 via R671. 5. At +15V, C635 takes about 0.2 milli-seconds to charge to 8.6V. 6. Zener diode D627 conducts, turning ON Q607. 7. Q607 in turn energizes the surge relay RY602. 8. RY602's contacts jumper (short) out current limiting thermistor TH600 so the monitor will have full power.

Operating Voltages and Resistances
Circuit Voltages Location IC1001/pin 5 Q608/Collector D628/Anode D627/Cathode Q607/base Q607/Collector R672/RY602 0V 2.3V 0V 0V 0V 0V Selected Part Values Part TH600 TH601 DGC Coil Function Surge Resistor Degauss Thermistor Degaussing Measured Resistance 6.5 ohms cold 4.2 ohms cold 15.6 ohms At Power ON 4.9V 0V 11.8V 11.8V 8.6V 0.72V 0V 2.92V After 2 seconds

Surge Protection Circuit
At power ON this monitor consumes power in two places: · Degaussing coil circuit = About 6 AC amps. · Monitor power supply = About 0.5 to 1 amp depending upon the charge of the filter capacitor (C611). The surge protection circuit reduces the amount of power and voltage fluctuations to the monitor's power supply until the degaussing circuit has completed its task. This is accomplished by placing a current limiting resistor (thermistor TH600) in series with the bridge rectifier D625. 1.8 sec after the power button is pressed, the current limiting resistor is jumped out of the circuit.

RY601

D628 R675

Q608 DIGITAL TRANSISTOR DEGAUSS PWM2 IC001/5

TH601 1 F601 6.3A AC R674 560k AC VA601 LF602 LFT C636 470pF C637 470pF ON/OFF S601 R604 2.2 OHMS 10W D605 4 R625 0.1 OHM DGC COIL +158V TO IC603/1 SRT T602/9

TH600 + C611 R605 470 2.7 OHMS 10W +15V R671 10k

RY602 R672 150 N R673 + C635 22 Q607 D627 8.2V

SURGE PROT.

DEGAUSSING / SURGE PROTECTION

1MON4 1196

1/19/00 11 29 99

20

21

Switching Oscillator
This switching oscillator stage generates seven voltages for the monitor to operate normally. The stage consist of three major parts: · Switching Regulator IC603 ­ Contains an oscillator that runs at 63kHz, 26kHz or at bursts of 18kHz. Duty cycle regulation. · Power Handling Q605 ­ A MOSFET can control the high current at the wide operating frequency of the oscillator. · Sine Resonate Transformer T602 ­ Produces the various voltages required by the monitor. This monitor's power supply has three operating modes. One mode is selected depending upon the amount of load. When the load has changed, measuring the current needed to restabilize the output voltage permits IC603 to select the same or another operating mode.

1. Switching Regulator IC603/pin 14 receives a voltage above 2.5V. IC603/pin 14 is labeled OOD for "On/Off Data". 2. Voltage input from IC603/pin 1 is permitted to leave Vaux IC603/pin 6 to charge external capacitor C613 until IC603's oscillator runs. Vaux is the supply input for the IC like Vcc. C613 must continue to supply power to the IC until the power supply stage develops voltage to keep C613 charged. 3. IC603's internal oscillator starts and approximately 65kHz is output IC603/pin 4.
ch1: pkpk= 386 V ch2: freq= 62.9kHz

T

1

Power Supply Operating Modes Mode 1. Normal (e.g. bright screen) 2. Light (e.g. screen saver) 3. Active off Oscillator Frequency 63kHz Characteristic Continuous 63kHz oscillator signal. Duty cycle is changed for regulation. Continuous 26kHz oscillator signal. Duty cycle is changed for regulation. 18.5msec. bursts of 18.2kHz, 6 times/second. The 18.2kHz is PWM.
2 CH1 100 V= CH2 10.0 V= MTB5.00us- 1.36dv ch1-

26kHz

18.2kHz 6Hz = burst rate

Start Up ­ Normal Mode
When the front panel power switch is pressed, +170V is applied through fusible resistor R625 to the switching oscillator stage. This voltage is evident at the SRT T602 transformer primary windings, Q605/D, and IC603/ pin 1. Oscillation does not start until IC603/pin 14 receives voltage. The following start up sequence occurs to power the monitor:

4. This signal is amplified by Q605 and applied to the primary winding of SRT transformer at T602/pin 5. 5. The SRT transformer has three groups of secondary windings: · Pins 10-15 supply power to the monitor. · Pins 16-18 supply voltage to the Horizontal centering circuit. · Pins 2-3 return a sample of the transformer voltage to IC603. 6. The secondary voltage from T602/pins 2 and 3 are separated into two paths before fed back to IC603, pins 13 and 7 for control. · IC603/pin 13 ­ The R635 path is used to monitor changes to the secondary load for mode changes between Normal, Light and Active off operation. · IC603/pin 7 ­ The path through D613, R642, D633, and R643 is used to coarse regulate the output voltage. IC603 uses this information to change the oscillator pulse width (duty cycle) for output voltage control. A second regulation path into IC603/pin 9 is used for fine voltage correction.

158V R625

L608 C612 R627 4.7M R693 4.7M
1

9

10

R626 47k, 3W

8 7 5

+9V +200V TO 5V D618 REGS. +80V 11 R645 D619

D614

VIN
14

OOB IC603 SW REG. CONT TEA1504 V CONTROL VAUX I SENSE

4

D609 Q605 2SK3265 D R636 D612 G S

12

C610 C617

+15V TO 12V REG.
14

D620

R628 560k D608 BURST TRIG

5.6V R629 820k

D611 R615 33 OHMS
5

R647 D622
15

R637 R640 0.39 OHMS 1W

R638 R641 0.47 OHMS 1W T602 SRT
13

R648

-15V

D621

9

R630
6

R639 18 OHMS C619

D623
16

+ C613 47

R643 22 OHMS DS
7

R649
17

DEM 13
8

2

R644 100

IRGF

11

R635 100k R642 D633 C620

+ H CENT CIRCUIT D624

3

18

D613 +200V IC609 REG. STBY 5V (TO CPU)

R650 D616 SCR

R632

R633

REGULATOR CIRCUIT

HEATER (CPU IC1001/8)

SWITCHING OSCILLATOR

3MON04 1198 1/28/00

22

23

Active off Mode
The monitor can also operate in an Active Off mode. When the computer is turned OFF, there is no video sync input the monitor. Within the monitor, this loss is detected by the CPU (not shown). The CPU turns ON SCR D616, which increases the error voltage. This increase to 6.5V is detected by IC603/pin 14 via D608 and the oscillator stops to lower the output voltage. Since it takes a longer time for the voltage to return to normal, the oscillator resumes in the low output Active Off or Burst mode. In the Active Off mode IC603 turns ON the power supply's oscillator in bursts, every 163msec (6 times/second). The bursts last 18.5msec.
, ch1: dT= 163ms dV=4.00 V

Active Off Power Supply Burst Name Channel 1 Channel 2 Time base Amplified Osc Oscillator Output Location Q605/D IC603/pin 4 200usec/div Voltage 180Vp-p 11Vp-p

These bursts provide sufficient voltage at T602/pin 14 to only regulator IC609. IC609 powers the CPU, IC1001. The SCR is reset because there is insufficient current to keep it latched.

Light Mode
T

1

From the Active Off mode, the monitor can return to the ON mode when input video sync is detected or if a front panel input has been selected. Both inputs are monitored by the CPU. The CPU discontinues the SCR (Heater) signal and turns ON both regulators. The regulators immediately load the power supply stage.
MTB50.0ms- 1.36dv ch1-

2 CH1 100 V= CH2 10.0 V=

Active Off Power Supply Burst Intervals Name Channel 1 Channel 2 Time base Amplified OSC Oscillator Output Location Q605/D IC603/pin 4 50msec/div Voltage 180Vp-p 11Vp-p

The decrease in peak to peak feedback voltage from T602/pin 2 causes IC603 to power up. IC603 first eliminates the bursts and provides a continuous oscillator signal from pin 4 (Light Operating Mode). If the Light Operating Mode does not bring the secondary voltage up fast enough, IC603 increases the frequency and pulse width to meet the power demand (normal mode). When the power demand is minimal, such as in screen saver or a front panel input in triggered with no video input, the power supply may choose the Light-operating mode. The monitor current is measured at IC603/pin 5. In this light mode, the power supply does not have to work as hard to maintain the secondary voltages that are used to drive the monitor. As a result, the oscillator frequency is only 26KHz in the light mode, instead of the normal 63kHz.

Each burst consists of oscillator pulses at 18.2kHz. These pulses change in width to regulate the power supply output voltages in the Active Off mode.
ch2: pkpk= 9.57 V ch2: freq= 20.8kHz

T

1

2 CH1 100 V= CH2 10.0 V= STOP MTB 200us- 1.36dv ch1-

158V R625

L608 C612 R627 4.7M R693 4.7M
1

9

10

R626 47k, 3W

8 7 5

+9V +200V TO 5V D618 REGS. +80V 11 R645 D619

D614

VIN
14

OOB IC603 SW REG. CONT TEA1504 V CONTROL VAUX I SENSE

4

D609 Q605 2SK3265 D R636 D612 G S

12

C610 C617

+15V TO 12V REG.
14

D620

R628 560k D608 BURST TRIG

5.6V R629 820k

D611 R615 33 OHMS
5

R647 D622
15

R637 R640 0.39 OHMS 1W

R638 R641 0.47 OHMS 1W T602 SRT
13

R648

-15V

D621

9

R630
6

R639 18 OHMS C619

D623
16

+ C613 47

R643 22 OHMS DS
7

R649
17

DEM 13
8

2

R644 100

IRGF

11

R635 100k R642 D633 C620

+ H CENT CIRCUIT D624

3

18

D613 +200V IC609 REG. STBY 5V (TO CPU)

R650 D616 SCR

R632

R633

REGULATOR CIRCUIT

HEATER (CPU IC1001/8)

SWITCHING OSCILLATOR

3MON04 1198 1/28/00

24

25

Mode Switching
By using three operating modes to maintain the output voltages, the power supply is more efficient. The correct operating mode is selected by IC603/ pin 14 for the Active Off Mode and maintained by using feedback from transformer T602/pin 2. This signal is reduced considerably by R635 as seen in the next waveform:
, ch1: pkpk= 42.0 V ch2: pkpk= 7.91 V

Power Supply Output Voltages Line @ Location 200V @ D614/C 80v @ D618/C 15V @ D619/C 9V @ D620/C 9V @ D621/C -15V @ D622/A + V @ D623/C & D624/A Normal/Light Mode 200V 77.5V 14.9V 8V 9.2V -14.8V +6.5V Active Off Mode 16.5V 6.82V 1.07V 1.75V 13.5V for CPU -1.2V +1.1V

1

T

Forced Normal Operating Mode
2 CH1 10.0 V= CH2 5.00 V~ MTB2.00us- 0.76dv ch1+

If the power supply will not enter the Normal Operational mode (stays in the Active Off / Burst Mode) this is because:
Location Voltage 30Vp-p 5Vp-p

Mode Sensing Name Channel 1 Channel 2 Time base Feedback DEM T602/pin 2 (D613/A) IC603/pin 13 2usec/div

· There is a short on one of T602 or FBT secondary loads. · Standby 5V is missing or CPU is defective. · SCR D616 is shorted. · The regulating circuit is defective. If you cannot find a short in one of the power supply loads or FBT loads, you can force the power supply to enter the Normal mode. This is done by: · Disabling the HV for your own safety. · Disabling the SCR on the +200V line. · Turning ON the +5V and +12V regulators. A service manual to locate the parts, a jumper wire to force the power supply into the Normal Power Mode and a 5V-power supply is needed to turn on the regulators. Warning - When repairing any electronic product, DO NOT PLUG THE PRODUCT DIRECTLY INTO AC. Plug the product into an isolation transformer and the transformer into AC to reduce damage and the danger to you when servicing.

Operating Voltages
IC603 DC Voltages Pin 1 2 3 4 5 6 7 Normal Mode 158V 0 0 2.6V .02V 11.4-12.5V 12.2V Stby Mode 165V 0 0 0.06V 0 9.1-9.7V 9.1-9.7V Pin 8 9 10 11 12 13 14 Normal Mode 2.4V 2.7V 0 0 0 0.8-1V 5.2V Stby Mode 2.5V 0.06-0.2V 0 0 0 0.07-.2V 5.6V

158V R625

L608 C612 R627 4.7M R693 4.7M
1

9

10

R626 47k, 3W

8 7 5

+9V +200V TO 5V D618 REGS. +80V 11 R645 D619

D614

VIN
14

OOB IC603 SW REG. CONT TEA1504 V CONTROL VAUX I SENSE

4

D609 Q605 2SK3265 D R636 D612 G S

12

C610 C617

+15V TO 12V REG.
14

D620

R628 560k D608 BURST TRIG

5.6V R629 820k

D611 R615 33 OHMS
5

R647 D622
15

R637 R640 0.39 OHMS 1W

R638 R641 0.47 OHMS 1W T602 SRT
13

R648

-15V

D621

9

R630
6

R639 18 OHMS C619

D623
16

+ C613 47

R643 22 OHMS DS
7

R649
17

DEM 13
8

2

R644 100

IRGF

11

R635 100k R642 D633 C620

+ H CENT CIRCUIT D624

3

18

D613 +200V IC609 REG. STBY 5V (TO CPU)

R650 D616 SCR

R632

R633

REGULATOR CIRCUIT

HEATER (CPU IC1001/8)

SWITCHING OSCILLATOR

3MON04 1198 1/28/00

26

27
The procedure is as follows: 1. Position the main board to access the power supply. You will not need the picture tube nor degaussing coil. You will need the +5 volt loads on the D board and the CRT's A board. 2. Disable the HV by shorting Q902's Source and Gate leads. Q902 is on the large heat sink on the main D board near the relays. The Source and Gate are the outer leads on this TO-220 case FET.
Q902 G Surge Relay RY602 S Degauss Relay RY601 Q901

6. Apply external +5Vdc in series with a diode to IC605/pin 1. This turns ON 5V regulator IC605 and 12V regulator IC604. You may want to place a diode in series with the external +5V power supply to prevent damaging your test equipment. Use the shield as a cold ground. Alternate procedure: If you do not want to use an external power supply, the monitor will normally enter the Active Off Mode after one minute. At that time, press a front panel mode button to return the Monitor to the Normal Power Mode. 7. Press the power ON button and the monitor's power supply will come up in the Normal mode and remain in that mode. After one minute without sync input, the CPU will turn ON the front panel Orange indicator, but the monitor voltages are active except for the final HV, Heater voltages and FBT voltages.

3. Disable SCR D616 by shorting diode D617 nearby. D617 is connected to the SCR's gate and cathode.

D617

K G A
4. Keep the Yoke connected to the D board (CN1 to CN501) so the unit will not go into ABL shutdown. 5. Keep the CRT's A board connected at CN306, CN309 and CN311 for CPU communications and power.

D616 SCR

158V R625

L608 C612 R627 4.7M R693 4.7M
1

9

10

R626 47k, 3W

8 7 5

+9V +200V TO 5V D618 REGS. +80V 11 R645 D619

D614

VIN
14

OOB IC603 SW REG. CONT TEA1504 V CONTROL VAUX I SENSE

4

D609 Q605 2SK3265 D R636 D612 G S

12

C610 C617

+15V TO 12V REG.
14

D620

R628 560k D608 BURST TRIG

5.6V R629 820k

D611 R615 33 OHMS
5

R647 D622
15

R637 R640 0.39 OHMS 1W

R638 R641 0.47 OHMS 1W T602 SRT
13

R648

-15V

D621

9

R630
6

R639 18 OHMS C619

D623
16

+ C613 47

R643 22 OHMS DS
7

R649
17

DEM 13
8

2

R644 100

IRGF

11

R635 100k R642 D633 C620

+ H CENT CIRCUIT D624

3

18

D613 +200V IC609 REG. STBY 5V (TO CPU)

R650 D616 SCR

R632

R633

REGULATOR CIRCUIT

HEATER (CPU IC1001/8)

SWITCHING OSCILLATOR

3MON04 1198 1/28/00

28

29

Switching Oscillator Part Functions
Power Supply Parts Functions Defective Parts D609, C612, C610, C617, D611, C619. R640, R641 R630 open (no error signal), R632, R633 D612 (18V zener) Purpose of Parts Q605 Protection Q605 Protection Q605 Protection Error detection circuit Possible symptoms Immediate Q605 failure Intermittent Q605 failure Power supply oscillator stops Power supply cycles between Normal and Active Off Modes. Blooming, Q605 gets too hot. Monitor dead, Repeated failure of IC603 and Q605. Oscillator at IC603/pin 4 starts for a few cycles and stops. Monitor momentarily powers up, then enters the Active Off mode. Monitor dead.

Oscillator frequencies off IC603 protection

D613, R642, D633

Powers IC603

Standby 5Vregulator for CPU.

CPU power

R693, R627

Oscillator Starting

158V R625

L608 C612 R627 4.7M R693 4.7M
1

9

10

R626 47k, 3W

8 7 5

+9V +200V TO 5V D618 REGS. +80V 11 R645 D619

D614

VIN
14

OOB IC603 SW REG. CONT TEA1504 V CONTROL VAUX I SENSE

4

D609 Q605 2SK3265 D R636 D612 G S

12

C610 C617

+15V TO 12V REG.
14

D620

R628 560k D608 BURST TRIG

5.6V R629 820k

D611 R615 33 OHMS
5

R647 D622
15

R637 R640 0.39 OHMS 1W

R638 R641 0.47 OHMS 1W T602 SRT
13

R648

-15V

D621

9

R630
6

R639 18 OHMS C619

D623
16

+ C613 47

R643 22 OHMS DS
7

R649
17

DEM 13
8

2

R644 100

IRGF

11

R635 100k R642 D633 C620

+ H CENT CIRCUIT D624

3

18

D613 +200V IC609 REG. STBY 5V (TO CPU)

R650 D616 SCR

R632

R633

REGULATOR CIRCUIT

HEATER (CPU IC1001/8)

SWITCHING OSCILLATOR

3MON04 1198 1/28/00

30

31

Low Voltage Regulating Circuit
Although the switching power supply oscillator runs while there is voltage at Vaux (IC603/pin 6), the power supply stage will not maintain the correct output voltage without the following: · T602 Feedback (DEM into IC603/pin 13) for low or over voltage protection · The Regulator Circuit (from D621 to V Ctrl @ IC603/pin 9) for voltage stability

Regulator Operation - Normal Mode
Regulation is performed by predominately IC608 in the normal, standby and suspended power modes. The voltage from a secondary winding of T602 at D621 is used for regulation. This sample voltage is reduced by resistor string R676, R681 and R682, then applied to IC608. IC608 (TL1431) is a error regulator IC designed to shunt (lower) its output voltage to ground until its input voltage returns to 2.5V. Capacitors C642, C641 and resistor R679 are used to slow the response time of shunt regulator IC608 and prevent oscillation. The output voltage from shunt regulator IC608/pin 3 is input to optical isolator IC607/pin 2. IC607 not only inverts the signal, but also provides electrical isolation between the input and output signal. Finally, IC607's output at pin 5 is applied to the switching power supply to adjust the pulse width of the oscillator signal for secondary voltage correction. If the output of transformer T602 increases, the final correction voltage fed back to the power supply oscillator at V Ctrl will also increase. This is shown in the chart below. In the power supply, as the V Ctrl voltage increases, the oscillator conduction time decreases. This decrease lowers the energy from T602's secondary windings, returning the voltage to normal.
Regulation Correction Path Power Supply Output (D621/C) Increases Shunt Reg. Input (IC608/pin 1) Increases Normal Mode Opto-Isolator Output IC607/pin 5) Increases Shunt Reg. Output (IC608/pin 3) Decreases

T602 Feedback
The DEM p-p feedback (fdbk) voltage from the Sine Resonate Transformer (SRT) T602 is used in the Normal Power Mode for protection. A peak voltage above or below limits will change the oscillator to lower T602's output voltage for safety. Low Voltage A severe short at a T602 secondary will drastically lower the DEM feedback voltage. For example, if this DEM feedback voltage were removed or shorted at IC603/pin 13, the following output voltages would reduce to +145V, +80V +56V, 8V +6V. these new levels: +200V High Voltage If the +200V output voltage rose to 220V, the oscillator would be momentarily inhibited. The oscillator would start and stop, causing the CPU voltage and green LED to also start and stop.

The Regulator Circuit
The regulator circuit has three major parts: · IC607 ­ Optical Isolator IC transfers correction voltage from the cold ground side to the oscillator's hot ground side. · Q609 ­ Used to regulate the oscillator during the Active Off (Burst) Mode so the standby regulator IC609 can produce standby +5V. · IC608 ­ Samples the +200 V B+ from T602 for voltage regulation in all power modes except Active Off. The regulator operates differently in: · The Normal, Standby, Suspended modes; and · The Active Off (Burst) Power Mode.

Regulator Defect - Open Circuit An open circuit in this regulation loop will cause 0V at V Ctrl. The switching power supply will then generate excessive voltage. The larger feedback voltage from T602 into the switching power supply (DEM) will shut off the power supply momentarily. This occurs when the +200V line reaches about +220V. When the voltage drops to about +180V, the oscillator will start again only to be shut off when it reaches +220V. The resultant power supply and front panel green LED will start and stop in unison at about 2 Hz.

00B

IC603,Q605 SWITCHING POWER DRIVE SUPPLY V CTRL VAUX DEM 12V
6 1

D614 T602 SRT

200V (SOURCE) D615

C650 100 R653 47k 2W
A G

D621

D608 D633 FDBK R677 100 D616
K

R630 220 3.4V R602 0 OHM
5

R667 47k2W Q606

2

6.9V

Q609

D63015V

STBY REG CIRCUIT D617 C628 2200

R657

C608 IC607 OP- ISOLATE TLP621D4 R678 560 C642
3

R685 R684 22

HEATER FROM IC1001/8

+

8V IC609 REG. STBY +5V

5.4V

R679 C641 2.5V
1

R682 D629

R676 R681 C644 0.05 R686

+200V

2

MAIN ERROR REGULATOR CIRCUIT

IC608 SHUNT REG. TL1431

R687

VOLTAGES WERE MEASURED IN THE NORMAL POWER MODE

L.V. REGULATOR CIRCUIT 32

6MON04 1202

1/24/00

33
One Oscillator Burst

Regulator Operation - Active Off Mode
In the active off mode, only the standby 5V is operational. Q609, IC607 and IC609 are used to maintain standby 5V for the CPU. CPU IC1001 activates the Active Off reduced power mode when both horizontal and vertical sync inputs are missing (computer OFF). The CPU (IC1001/pin 8 = LOW) turns OFF the CRT heater and Q606 after the loss is detected. The path used to enter the Active Off Mode and for Standby 5V regulation are the same: 1. One minute after turn ON, if the CPU IC1001 does not detect H and V sync, IC1001/pin 8 goes LOW. Both the heater regulator IC610 (not shown) and Q606 are turned OFF. 2. With Q606 Off, D616's gate is no longer grounded (enabled). 3. Pulses from D615 pass through C650, R653 and R664 to the gate of D616, turning this SCR ON. 4. When D616 turns ON, the +200V line is connected to the 8V line at D621/Cathode. C628 on the 8V line charges. 5. When the 8V line rises to about 15.6V zener D630, Q608 and IC607 all turn ON. This causes the switching power supply input at V Ctrl to be HIGH. 6. The prolonged HIGH that is applied to the switching oscillator at V Ctrl first reduces the oscillator's ON time (in an attempt to lower the output voltage) and then finally shuts off the oscillator as it enters the Active Off or Burst Mode. 7. In the Active Off / Burst Mode, the oscillator is turned on in groups appearing as bursts every 0.6 seconds. This burst will provide a small amount of power to supply the CPU but not the remainder of the monitor circuits.
ch2: pkpk= 9.57 V ch2: freq= 20.8kHz

Name Channel 1 Channel 2 Time base Amplified Osc Oscillator Output

Location Q605/D IC603/pin 4 200usec/div

Voltage 180Vp-p 11Vp-p

8. In this Active Off/ Burst Mode, the voltage to standby regulator IC609 must still be regulated or it will become excessive (about 40V). Q609 performs the regulation for the standby 5V. Because the D616 SCR is still turned ON, the input voltage from D621 is increasing but in bursts. When the input voltage at D621/C reaches about 15.6V, zener D630 conducts turning on Q609. 9. Q609 turns on IC607, which outputs an oscillator correction voltage directly proportional to the input voltage from D621/C. The correction voltage corrects the pulse width of the burst signal to keep the average voltage at D621/C at about 12V in the Active Off / Burst Mode.

Measured Voltages
Measured Voltages Location IC607/pin 1 IC607/pin 2 IC607/pin 5 hot ground IC607/pin 6 hot ground Q609/Base Q609/Collector IC608/pin 1 IC608/pin 3 D616/Anode D616/Gate Function Supply voltage (input) Input Output Supply voltage (output) Input Output Input Output +200 B+ Burst Mode trigger Regulator input Normal Mode 8.1V 6.9V 3.4V 12.5V 0V 6.9V 2.48V 5.39V 199.4V 8.86V 9.53V Active Off Mode 13.3-13.4V 12.5-12.7V 0.18-0.21V 9.3-9.5V 0.1 12.5-12.7V 0.2 12.5-12.7V 15.9-16V 13.2-13.4 13.4-13.5V

T

1

2 CH1 100 V= CH2 10.0 V= STOP MTB 200us- 1.36dv ch1-

D616/Cathode

00B

IC603,Q605 SWITCHING POWER DRIVE SUPPLY V CTRL VAUX DEM 12V
6 1

D614 T602 SRT

200V (SOURCE) D615

C650 100 R653 47k 2W
A G

D621

D608 D633 FDBK R677 100 D616
K

R630 220 3.4V R602 0 OHM
5

R667 47k2W Q606

2

6.9V

Q609

D63015V

STBY REG CIRCUIT D617 C628 2200

R657

C608 IC607 OP- ISOLATE TLP621D4 R678 560 C642
3

R685 R684 22

HEATER FROM IC1001/8

+

8V IC609 REG. STBY +5V

5.4V

R679 C641 2.5V
1

R682 D629

R676 R681 C644 0.05 R686

+200V

2

MAIN ERROR REGULATOR CIRCUIT

IC608 SHUNT REG. TL1431

R687

VOLTAGES WERE MEASURED IN THE NORMAL POWER MODE

L.V. REGULATOR CIRCUIT 34

6MON04 1202

1/24/00

35
1 2 IC607 Isolator 6 5 1 (in) 2 (gnd) 3 (out) IC608 5V Regulator G A K D616 SCR

Green LED is ON. Only the standby voltage is present.

CPU is functioning in the Normal Power Mode but the power supply is in the Active Off Mode.

Simulated Defects and Symptoms
Simulated Defects Symptoms Picture is dim or dark. All LV PS voltages are low (+200V = 145V) Cause 1. Short or excessive load in T602 s secondary winding. 2. No DEM feedback voltage to PS oscillator. Green LED flashes. PS oscillator chirps as it powers up and shuts down. Power Supply voltages are high. The regulation loop is open. Troubleshooting Measure all secondary voltages. The one that is very low is being loaded down. If they are all proportionally low, IC603/pin 13 (DEM) is not getting feedback signal. Test D616 for shorts and disable if good by shorting G-K. Measure voltages in Regulation Correction Path chart to see what voltage does not change while the oscillator is chirping.

Test D616 (short) and Q606 (open) or pull D616 out of circuit to see if the Normal mode is possible. Measure D621/C voltage. 8V is normal. Higher voltages means Q609 or D616 is shorted. Lower voltage means D630 is shorted. If the Orange LED lights after one minute, the CPU senses no sync and it is responding normally. The problem is in the Active Off trigger circuitry about Q606, D616 and D617. Original IC609 was open. A replacement IC609 gets hot before failing.

Even without the video cable connected, the monitor stays in the Normal Mode (does not go into the Active Off Mode). Repeated Stby 5V IC609 regulator failure. Input measures 40V instead of 12V in the Active Off Mode.

There could be noise detected by the CPU and mistaken for sync. The Active Off trigger circuit is not responding. Standby regulator input voltage is not being regulated. Q609 and D630 are suspect.

00B

IC603,Q605 SWITCHING POWER DRIVE SUPPLY V CTRL VAUX DEM 12V
6 1

D614 T602 SRT

200V (SOURCE) D615

C650 100 R653 47k 2W
A G

D621

D608 D633 FDBK R677 100 D616
K

R630 220 3.4V R602 0 OHM
5

R667 47k2W Q606

2

6.9V

Q609

D63015V

STBY REG CIRCUIT D617 C628 2200

R657

C608 IC607 OP- ISOLATE TLP621D4 R678 560 C642
3

R685 R684 22

HEATER FROM IC1001/8

+

8V IC609 REG. STBY +5V

5.4V

R679 C641 2.5V
1

R682 D629

R676 R681 C644 0.05 R686

+200V

2

MAIN ERROR REGULATOR CIRCUIT

IC608 SHUNT REG. TL1431

R687

VOLTAGES WERE MEASURED IN THE NORMAL POWER MODE

L.V. REGULATOR CIRCUIT 36

6MON04 1202

1/24/00

37

Video Block
The Video Processing Block contains several stages: · · · RGB signal processing from the computer to the CRT cathodes OSD for Menu features CRT Bias

ages necessary. Adjustments to this data are made using an external computer using DAS software.

Troubleshooting
Dark screen - Even if RGB video is input, the monitor the signal can be inhibited at several ICs along the path:
RGB Signal Inhibited causing a Dark Screen Blockage Location IC008 Input Switch IC001 RGB Preamp Reason for blockage Input not selected. CPU detects no input sync. No IIC data input IC003. IC003 Blanking output line held HIGH IC002 RGB Output CRT +80V B+ missing. No G2 voltage. Cutoff voltage set too high. Check for Slide front panel input switch to correct position Blk signal from IC003. LOW = Normal. HIGH = OSD/blk interval. Data/Clk from CPU to OSD IC003. H & V sync input CPU. Check for +80V from LV power supply. G2 voltage from FBT. IC004 in and out voltages. IC001 Bkg output voltages.

RGB Signal Process
Two computers can be connected to the CPD-G400 monitor. A front panel switch selects the input used. The switch signal is applied to IC008, which selects the RGB signal. The input switch is also connected to IC009 to simultaneously select the sync. The selected horizontal and vertical sync signals are used to lock the oscillator inside CPU IC001. The RGB signal is amplified by RGB Pre-amplifier IC001 and will output this IC unless the alternate OSD signal containing menu information is switched in. The Input/OSD switch is controlled by IC003's Blk signal. IC002 amplifies the input or/and OSD input to a high level to drive the CRT cathodes.

OSD
The OSD IC003 makes the menu characters, white screen (for the Aging Mode and the Image Restoration feature) and translates the analog cathode current levels (Ik) into digital data for CPU IC1001. IC003 needs serial data, clock and the H & V oscillator inputs to support the RGB and Blk outputs. These two outputs are used to make a menu display or white screen. The Ik input is used when the image restoration feature is activated from the menu. The Ik voltages are then sent out as data to the CPU for computation.

No Menu Messages No OSD or White Screen in the Aging Mode Location IC003 OSD Reason Blk output held HIGH No H or V input No Data or Clock IC1001 CPU No H or V osc output No Data or Clock out Check for OSD RGB output from IC003 when Blk is HIGH. H & V sync, data and clock input. H & V oscillator, data and clock input.

CRT Bias
Memory IC1005 stores the CRT bias parameters. They are loaded into the CPU when the CPU is reset at the time the power switch is pressed. G2 and cathode DC threshold (background/cutoff) voltage data are sent along the IIC bus into RGB Preamp IC001. IC001 translates the data into analog voltages to make G2 and background voltages for the CRT. Additional G2 and background driver ICs are needed to make the high volt-

15M G2 CONTROL IN 1 RGB 1 IC008 INPUT SEL RGB IC001 RGB PRE-AMP. OSD RGB RGB IC002 RGB OUT RGB BKG IC004 RGB CUT-OFF A BD. G2 RGB CRT

RGB 2 IN 1 IN 2 IN 2 15M H+V SYNC 1 H+V SYNC 2

BLK

S2001 INPUT SW. IC009 SYNC SEL. SW.

IC003 OSD

1k

H+V OSC.

TO DPU IC801 (N BD.) 11C DATA/CLK BUS

V+H SYNC

11C DATA CLK

IC1001 CPU

TO: DPU IC801 (N BD.) MEMORY UIC1005 (D BD.)

VIDEO BLOCK 38

17MON04 1221 1/18/00

39

Input
Name

Input Select Switch IC008 Input Location RGB input 1 RGB input 2 Input Sw Pins 2, 5, 7 Pins 11, 13, 16 Pin 19 Level 1Vp-p 1Vp-p Low = input 1 High = input 2 Sync Switch IC009 Name Location Vertical Sync Sync on Green Horiz & Vert Sync input 1 Horiz & Vert Sync input 2 Sync on Green Input 1 Sync on Green Input 2 Input Sw Input Level Pins 5, 12. 4p-p Pins 3, 13. 4Vp-p Pin 2 Pin 1 4p-p 4Vp-p Pin 15 4Vp-p Output Location Pins 5, 14 Level 45Vp-p Output Location Pins 27, 30, 35 Level 1Vp-p

Input/Output Signals
This monitor can be connected to two computers. A front panel switch selects input 1 or input 2. Each input is identical except for the Plug and Play communications. Input 2 only sends unidirectional plug and play monitor information to the computer (DDC1 format). Input 1 has bi-directional Plug and Play communications (supporting DDC1, DDC2B, & DDC2Bi formats). An explanation of Plug and Play can be found in the appendix of this book. The signals at the two inputs can be summarized in these charts:
Input 1 Inputs from computer Outputs to computer RGB video signal Horizontal Sync

Plug and Play DDC1, Unidirectional data or DDC2B / DDC2Bi Bi-directional data. If the CPU receives the appropriate DDC commands, it will operate in the bidirectional mode. Otherwise it will assume the DDC1 read only mode when triggered by vertical sync. Input 2

Inputs from computer Outputs to computer

RGB video signal

Horizontal Sync

Vertical Sync

Sync on Green

Pins 7, 10, Low = input 1 11 High = input 2 DDC1 IC007

Plug and Play DDC1, Unidirectional data from the monitor. DDC1 data is only output when Vertical Sync is received.

Signal Levels
For signal tracing, the signal levels in this stage are shown in the charts for each IC. IC008 and IC009 are used to select one of two RGB and sync inputs the monitor will use. The S2001 input switch is located under the bezel and its voltage is applied to both ICs. IC007 contains Plug and Play information about the monitor's resolution and sync speeds. This information is sent to the computer so the computer will only choose a sync speed the monitor can support (no loss of sync when entering a software program).

Name V Clock DDC Clk

Location Pin 7 Pin 6

Signal Level 4p-p 4.5Vp-p 5Vp-p

Comments Input sync Output when V clock is input Only input when timing is needed.

DDC Data Pin 5

+5V

CN313
6 2 4 8 9

1

3

4

6 24 28 31 36

R B G

VD HD

R1 B2 5 G1
2 7

C130
35

R OUT G OUT C230 B OUT C330 0.22 STBY +5V 1Vp-p TO RGB PRE-AMP IC001/10-13

INPUT 1 15M DDC CN310 H BD.

3 2 2 3 19

IC008 INPUT SELECT M52758FP R2 G2 B2
11 13 16

30

27

DDC DATA/CLK TO CPU ICIC1001/34,35 D BD.

CN 1003/ 311

INPUT SEL SW. S2001 C065 47 + Q005 BUFF.

INPUTJACK No.2

IN 1

INPUT SW. S2001
1 2

IN 2 +5V

16 2

CN2001/ 8 6 2004

2

CN1002/CN309 RGB TO IC008/ 11,13,16 INPUT 2 15M DDC DATA/CLK

G1 12 V1 IC009 5 H1 SYNC SW. 14 7 C BU4053B R055 100 0V=1 10 B 5 R054 5V=2 11 A 10k `5 INPUT SEL G2 V2 H2 13 3 TO IC008/19 1 C064 + Q004 VCLK
8 5 6

V OUT H OUT G OUT

TO INVERTER IC006/1,11 TO SYNC SEP CIRCUIT Q002/B

A BD.

IC007 DDC 24LC21

7

STBY +5V

INPUT

7MON04 1208 1/19/00

40

41

Video Output
Location

RGB Signal Path DC 1.9V 2.8V 43V IC001/pins 10-12 IC002/pins 8, 9 & 11. IC002/pins 1, 3 & 5.

Signal input from computer AC 1Vp-p 4Vp-p 56Vp-p Wave Shape

Overview
The video output stage consists of several ICs that: · Amplify the computer RGB signal; and · Provide CRT bias to display the RGB signal. Two features result in additional usage of ICs in this video output stage: · · An onscreen messages (CPU IC1001, OSD IC003, and RGB Preamp IC001) Image Restoration (CPU IC1001, Cutoff Control IC004, OSD IC003, and RGB Preamp IC001)

Aging Signal The aging mode is used to warm up the monitor prior to adjustments. In this warm up mode, the screen is bright and the front panel LED alternates between green and orange. The Aging Mode is entered when there is no computer signal input to the monitor and the control button is moved to the left and held for two seconds. When the CPU detects no sync input and the control button was held left, the Active Off Mode is suspended and the Aging Mode begins. CPU IC1001 sends data and clock to the instruct OSD IC003/pins 3 and 4 to generate a white screen. The white screen aging signal leaves as pulses from the RGB outputs at IC003/pins 14-16. They are accompanied by blanking signal of the same polarity at IC003/pin.
Aging Signal Output Name OSD/Aging signal Location IC003/pin 14-16 Wave Shape

RGB Amplification
RGB Signal The RGB signal from the computer is amplified by two ICs before being capacitor coupled to the three cathodes of the CRT. RGB Preamp IC001/ pins10-12 receives the computer RGB signal selected from inputs 1 or 2. IC001 amplifies the 1Vp-p signal input to 4Vp-p output at pins 20, 23, and 27 respectively. IC001 also serves to switch to the OSD signal input pins 13-15 and use serial data input pins 3-4 to control the G2 voltage from pin 29. The 4Vp-p RGB output IC001/pins 20, 23, and 27 are sent to second amp IC002. The sole function of this IC is to increase the 4Vp-p input to about 56Vp-p output at pins 1, 3, and 5, using +80V from the low voltage supply. IC002 is protected from CRT voltage spikes due to internal arcing by diodes D104 and D105. Similar diodes protect the G & B outputs at IC002/ pins 1 and 2, but they are not shown for simplicity. The 56Vp-p RGB signal is capacitor coupled to the CRT cathodes.

bright FBlk IC003/pin 17 (switching/unblanking) The RGB Preamp IC001 serves as an RGB preamp and a switch. The blanking signal goes HIGH to disable the RGB signal and enable the OSD signal from IC001/pins 13-1