Text preview for : DP14LT7N_ING.IN050.1.09.pdf part of Samsung DP14LS/LT DP15LS/LT Service Manual Samsung 450B / 550B



Back to : 450B-part1.zip | Home

6 Troubleshooting
6-1 General Troubleshooting
Notes: 1. If a picture does not appear, fully rotate the brightness and contrast controls clockwise and reinspect. 2. Check the following circuits. No raster appears: Power circuit, Horizontal output circuit, H/V control circuit, and H/V output circuit. High voltage develops but no raster appears: Video output circuits. High voltage does not develop: Horizontal output circuits.

6-1-1 No Picture
Check signal cable connection, H/V Sync input. Check Timing mode (14": 30~55kHz, 15": 30~61kHz). Check Cont, Bright key (all Max) and Screen VR (G2).

Check key components of secondary part. : D406, D407, D408, D515, Q402, Q410, Q504, Rectifier diodes (D608 ~ D612), IC101 (Vcc~GND)

Check key components of primary part. : D601 ~ D607, FH601, IC601, TH602

Refer to 6-2-16 No Video.

Check SW601 (Power key)

Refer to 6-2-1 No Power.

Refer to 6-2-3 No Raster and 6-2-12 High Voltage Failure.

Refer to 6-2-17 Micom Failure.

Refer to 6-2-13 I2C Failure.

DP14L*/DP15L*

6-1

6 Troubleshooting

6-1-2 Shut Down
Check X-ray protection circuit. : D502, D503, R510

Check key components of secondary part. : D406, D407, D408, D515, IC101 (Vcc ~ GND) Q402, Q504, Rectifier diodes

Check and replace IC601.

Refer to 6-2-1 No Power.

Refer to 6-2-3 No Raster and 6-2-12 High Voltage Failure.

Refer to 6-2-17 Micom Failure.

Refer to 6-2-13 I2C Failure.

6-2

DP14L*/DP15L*

6 Troubleshooting

6-1-3 No Video or Missing Colors
Check signal cable connection, H/V Sync input. Check Timing mode (14": 30~55kHz, 15": 30~61kHz). Check Cont, Brit key (all Max) and Screen VR (G2).

WAVEFORMS
19 46.4 V (SK103, G)

22

Are 0.7Vp-p video input on CN202_2 R, G, B? Yes

No

Check signal cable and generator.
CH1 P-P = 46.4 V CH1 RMS = 38.16 V

22 1.016 V (CN202_2, #2,4,6)

19

Are proper waveform on SK103's R, G, B cathode? Yes

No

Refer to 6-2-16 No Video.

CH1 P-P = 1.016 V

CH1 RMS = 174.4 mV

Is G2 and heater voltage OK?

No

Check and replace SK103 and some parts around it.

Yes Change CRT and replace it.

6-1-4 Visible Retrace
Check white balance adjustment.

WAVEFORMS
17 35.2 V (SK103, G1)

Is G2 voltage (Screen VR) OK?

No

Adjust Screen VR to 0.4~0.6F/L (back raster) at cont, bright all max.
CH1 P-P = 35.2 V CH1 RMS = 80.84 V

Yes
25

25 4.96 V (IC201, #30)

Is V_sync input on Q301 base?

No

Check V_sync input line.

Yes
17

Is proper G1 pulse on SK103's G1 pin? Yes Check and replace CRT.

No

Check C306, C506, D504 Q301, Q501 and around parts.

CH1 P-P = 4.96 V

CH1 RMS = 350 mV

DP14L*/DP15L*

6-3

6 Troubleshooting

6-1-5 Unsynchronized image
Check the connection of signal cable.

24

Are H/V sync input on IC201's Pins 30 and 31? 25 Yes

No

Check H/V sync input line.

No

Refer to 6-2-17 Micom Failure.

26

Are H/V sync input on IC401's Pins 1 and 2? 27 Yes

No

Check H/V sync input line.

No

Check and replace IC201.

WAVEFORMS
24 5.28 V (IC201, #31) 25 4.96 V (IC201, #30)

Refer to 6-2-12 High Voltage Failure. Yes Check and replace IC401.

CH1 P-P = 5.28 V

CH1 RMS = 1.218 V

CH1 P-P = 4.96 V

CH1 RMS = 350 mV

26 5.48 V (IC401, #1)

27 4.48 V (IC401, #2)

CH1 P-P = 5.48 V

CH1 RMS = 1.362 V

CH1 P-P = 4.48 V

CH1 RMS = 284 mV

6-1-6 Misconvergence
Readjust Misconvergence.

Spec in? (Center : 0.3 mm, Cornor : 0.4 mm) Yes Done

No

Change CRT and readjust Miconvergence and color.

6-4

DP14L*/DP15L*

6 Troubleshooting

6-1-7 Poor Focus
Adjust Focus VR.

Improved Focus?

Yes

Aging monitor and check focus change for 1~2 hours.

No Check Focus lead from FBT to CRT Socket. Yes Are the CRT Socket and connection OK? Yes Check and replace CRT. No Replace and connect it.

6-1-8 Purity Failure

Degaussing

Is purity OK?

Yes

Done

No IS degaussing circuit OK? No Refer to 6-2-20 Degaussing Failure.

Yes Check if there is strong electric or magnetic fields near user's circumstance? No Change CRT and readjust misconvergence and color. Yes Recommend free electric or magnetic field.

DP14L*/DP15L*

6-5

6 Troubleshooting

6-2 Detail Repair Section
Notes: 1. If a picture does not appear check first if AC power cord is plugged or not, if signal cable is connected or not, if signal generator (PC) is operated well or not (DPMS mode) if the Timing mode is out of spec or not (14": 30~55 kHz, 15": 30~61 kHz)

6-2-1 No Power
Check and replace D406, D407, D408, IC101, Q402, Q410, Q504

Does recitfied voltages of secondary part appear on C620, C622, C623, C624, C630? No Are D608 ~ D612 OK?

Yes

Refer to 6-2-3 No Raster and 6-2-12 High Voltage Failure.

No

Replace it.

No

Desolder IC601's Pin 1.

Yes Does rectified voltage (1.4 x AC input) of primary part appear on C607? Yes
1

No

Check and replace D601~D607, FH601, TH602.

Does rectified voltage (1.4 x AC input) of primary part appear on C617? Yes No

Check and replace IC601, T601. No Check and replace T601 and around parts. No

Is IC601's Pin 1 OK?

Yes
2

Is IC601's Pin 5 OK?

Yes Check and Replace IC601, T601. Check and replace D602, D603, D607, IC601, T602.

WAVEFORMS
1 410 V (IC601, #1) 2 8.40 V (IC601, #5)

CH1 P-P = 410 V

CH1 RMS = 332.8 V

CH1 P-P = 8.40 V

CH1 RMS = 4.680 V

6-6

DP14L*/DP15L*

6 Troubleshooting

6-2-2 DPMS Failure
6-2-2 (a) Off Mode (No H/V sync) Make sure that there is No H/V sync from signal generator. (Signal cable should be connected)

Is LED blinking? (1 sec toggle)

Yes

Is OP201 OK?

Yes

Check and replace OP201.

No

No Check and replace IC201.

Are there 0V on IC201's Pin 5 (sus) and 0V on IC201's Pin 6 (off)? Yes +12 V Off?

No

Check and replace IC201.

No

Check and replace Q605 ~ Q608.

Yes +6.3 V line Off? No Check and replace Q603, Q604.

Yes Done

DP14L*/DP15L*

6-7

6 Troubleshooting 6-2-2 (b) Suspend Mode (H sync: OK, V sync: No) Make sure that H sync is OK and V sync is not. (Signal cable should be connected)

Is LED blinking? (0.5 sec toggle) No

Yes

Is OP201 OK? No Check and replace IC201.

Yes

Check and replace OP201.

Are there 0V on IC201's Pin 5 (sus) and 5V on IC201's Pin 6 (off)? Yes +12 V Off? Yes Done

No

Check and replace IC201.

No

Check and replace Q605 ~ Q608.

6-2-2 (c) Stand-by Mode (H sync: No, V sync: OK) Make sure that H sync is not and V sync is OK. (Signal cable should be connected)

Is LED blinking? (0.5 sec toggle) No

Yes

Is OP201 OK? No Check and replace IC201.

Yes

Check and replace OP201.

Are there 5V on IC201's Pin 5 (sus) and 0V on IC201's Pin 6 (off)? Yes Is high voltage On? Yes Video Mute? Yes Done 6-8

No

Check and replace IC201.

No

Refer to 6-2-3 No Raster and 6-2-12 High Voltage Failure.

No

Refer to 6-2-16 No Video and 6-2-13 I2C Failure.

DP14L*/DP15L*

6 Troubleshooting

6-2-3 No Raster : No Raster means (Power: OK, High Voltage: No)
Is 53 V on C507? No

Refer to 6-2-1 No Power.

Yes Is 12 V on C628? Yes Is 0 V on IC201's Pin 5 (sus)? Yes Check and replace Q602, Q605, Q606, IC101, IC401.

No

No Are H/V sync on IC201's Pins 30 and 31? No Check signal cable and pattern. Yes Check and replace IC201.

3

Does oscillation waveform appear on IC401's Pin 6? Yes

No

WAVEFORMS
Check and replace IC401.
3 5.12 V (IC401, #6)

4

Does horizontal output waveform appear on IC401's Pin 26? Yes Is Q402 OK?

No

Check and replace Q401, Q402, Q504, T401, T501.
CH1 P-P = 5.12 V CH1 RMS = 4.256 V

4 4.60 V (IC401, #26)

No

Replace it.

Yes
CH1 P-P = 4.60 V CH1 RMS = 3.054 V

Is Q504 OK?

No

Replace it.

Yes Check and replace D407, D408, D409, D515.

Operating? Yes Check and replace C506, D503, D504, D505, IC401, Q401, T401 , T501, CRT. DP14L*/DP15L* 6-9

6 Troubleshooting

6-2-4 S-correction Failure
Symptoms: Poor Horizontal linearity Corner: wide, Center: narrow or Corner: narrow, Center: wide Are S1 and S2 OK at IC201's Pins 9 and 10? Yes No No

Are Q405 and Q407 OK?

Replace Q405, Q407.

Yes Check and replace IC201. No

Are Q406 and Q408 OK?

Replace it.

Yes Check and replace C431, C433, C434, D412, D413, Q405, Q407. Table 6-1. 31 ~ 35 S1 S2 0V 0V 35 ~ 40 0V 5V 40 ~ 49 5V 0V 49 ~ 61 5V 5V

* As CRT vendor and inch, there are differential items like C431, C433, C434, L401, R231, R441. If you want to change a PCB board to another one that is for different CRT and inch, you have to change differential items at schematic diagram.

6-2-5 H-Linearity Failure
Are code nomber and polarity of L401 right? Yes Are C427, D409, R423 OK? No Check and replace it. No

Check and replace it.

Yes Refer to 6-2-4 S-correction Failure.

6-10

DP14L*/DP15L*

6 Troubleshooting

6-2-6 Invariable H_Size
Are D414, Q411 and Q412 OK? No

Replace it.

Yes Does the PWM duty of IC201's Pin 22 vary, pressing H_Size button? No Yes Is Q409 OK? No Check and replace Q409.

No Replace IC201.

WAVEFORMS
8

Is paravola waveform on IC401's Pin 24? Yes

No

Replace IC401.

8 1.12 V (IC401, #24)

Check and replace Q409, Q410, L402.
CH1 P-P = 1.12 V CH1 RMS = 3.094 V

6-2-7 Abnormal H_Size
Check if R441 are right as CRT differential items?

Does PWM duty of IC201's Pin 22 vary with different timings? (Low freq. : narrow duty High freq. : wide duty) Yes Does the FBT B+ voltage on T501's Pin 2 vary with different timings? Yes Adjust horizontal minimum size with softjig. (Refer to 5-2-1)

No

Check and replace IC201 and some parts around it.

No

Refer to 6-2-12 High Voltage Failure.

DP14L*/DP15L*

6-11

6 Troubleshooting

6-2-8 S_Pin, Trap, Para, V_Lin, Pin_Bal Failure
Key check (6-2-19)

WAVEFORMS
8 1.12 V (IC401, #24)

8

Is IC401's Pin 24 OK?

No

Check and replace IC401.

Yes
CH1 P-P = 1.12 V CH1 RMS = 3.094 V

Refer to 6-2-13 I2C Failure.

6-2-9 Tilt Failure

Check tilt connector. (CN303)

Key check (6-2-19)

Does the PWM duty of IC201's Pin 21 vary, pressing tilt and + or key? No Does the output voltage of IC302's Pin 1 vary, pressing tilt and + or key? Yes Check and replace CRT.

No

Check and replace IC201, IC302.

No

Check and replace IC302, +13 V and 12 V line.

6-12

DP14L*/DP15L*

6 Troubleshooting

6-2-10 Vertical Deflection Failure
Symptoms: One horizontal line Rainbow color, No Video No

Are +13 V, 12 V line OK?

Check and replace D608, D609, IC301, IC302.

Yes
9

Is V_out waveform on IC401's Pin 23? Yes

No

Is 8 V on IC401's Pin 21?

No

Check and replace R307, R308, IC401.

Yes Check and replace IC401.

10

Is V_deflection waveform on IC301's Pin 6? Yes Refer to 6-2-13 I2C Failure.

No

Check and replace IC301, R305, R306, and some parts around it.

WAVEFORMS
9 3.16 V (IC401, #23) 10 50.8 V (IC301, #6)

CH1 P-P = 3.16 V

CH1 RMS = 3.686 V

CH1 P-P = 50.8 V

CH1 RMS = 7.04 V

6-2-11 Invariable V_Size or V_Position WAVEFORMS
9 3.16 V (IC401, #23)

Key check (6-2-18)

9

Does V_Out (IC401's Pin 23) vary, pressing V_Size or V_Posi key? No Refer to 6-2-13 I2C Failure.

Yes

Check and replace IC301 and some parts around it.
CH1 P-P = 3.16 V CH1 RMS = 3.686 V

DP14L*/DP15L*

6-13

6 Troubleshooting

6-2-12 High Voltage Failure
Symptoms 1: No Power No Raster Unstable operation (Fixed FBT B+ voltage with different H_frequency, Over 31 kHz: whistle sound, Narrow H_Size, Unsynchronized image, 31 kHz: OK) No

Is 53 V on C623?

Refer to 6-2-1 No Power.

Yes
13

Is Q504's drain waveform ok?

No

Are D515, L501, Q504 ok? Yes Are D403, D408, D409, Q402 and Q411, Q412 ok? Yes Check and replace AFC input line from T501 to IC401's Pin 12. : C408, R406.

No

Check and replace it.

Yes

No

Check and replace it.

Are D502, D503, R509, R510 ok?

No

Check and replace it.

Yes Does B_Out duty of IC401's Pin 28 vary with different H_frequency and image load (Full White or No Video)? Yes Check and replace Q502, Q503, IC401, T501. No Check and replace Q502, Q503, IC401, T501 and REG_IN line to IC401's Pin 15.

12

WAVEFORMS
12 14.0 V (IC401, #28) 13 136 V (Q504, Drain)

CH1 P-P = 14.0 V

CH1 RMS = 7.34 V

CH1 P-P = 136 V

CH1 RMS = 78.3 V

6-14

DP14L*/DP15L*

6 Troubleshooting Symptoms 2: X-ray protection One vertical line and then high voltage shut down. No

Are C417, C504, D502, D503, R509 and R510 ok? Yes Check and replace D407, D408, D414, Q402, Q504, IC401.

Check and replace it.

Check and replace IC201.

6-2-13 I2C Failure
Almost data (Horizontal drive duty, FBT B+ duty, display image data, color data) is transferred from IC201 to IC203 and IC401 through I2C data line during power on. After user adjusts display image data, contrast and brightness data, these are saved to IC203.

Key check (6-2-18)

WAVEFORMS
14 5.92 V (IC203, #5, 6)

Is 5 V on IC401's Pin 32 and IC203's Pin 8? Yes
14

No

Check and replace it.
CH1 P-P = 5.92 V CH1 RMS = 3.812 V

Is there data communication on IC401's Pins 30 and 31? Yes Is there data communication on IC401's Pins 30 and 31 during I2C function? (H/V Posi, V_Size, S_Pin, Trap, Cont, Bright) Yes Done

No

CH1 : IC401's Pin 31 CH2 : IC401's Pin 30

No

14

Check I2C data and clock line.

Check and replace I2C devices. (IC201, IC203, IC401)

DP14L*/DP15L*

6-15

6 Troubleshooting

6-2-14 ABL Failure
Symptoms : Full white luminance is too bright. (ABL minium is over 35 F/L) Full white luminance is too dark. (ABL maximum is under 35 F/L) The luminance of full white and No Video are almost same.

Display the full white pattern.

Check connections between CN105 and CN202.

No

Does full white luminance vary, adjusting ABL step with Softjig? Yes

Does the PWM duty of IC201's Pin 25 vary adjusting ABL step? No Check and replace IC201 and around parts.

Yes

Does the voltage of IC101's Pin 8 vary between full white and No Video?
F/W: 4.1~4.3V No Video: 5.3~6.0V

Yes

Check and replace IC101.

No Yes

Does T501's Pin 8 voltage vary between full white and No Video?
F/W: 1.5~3.0V No Video: 5.5~7.0V

Check and replace D506, IC101.

No No

Are 12 V line, R523, R523 ok? Yes Check and replace T501 and CRT.

Replace it.

6-16

DP14L*/DP15L*

6 Troubleshooting

6-2-15 Invariable Contrast, Brightness Control
Refer to 6-2-18 Key Check. (Contrast, Brightness)

WAVEFORMS
15 3.16 V (IC101, #21)

I2C check (6-2-13) Yes
15
CH1 P-P = 3.16 V CH1 RMS = 1.008 V

Does IC101's output (Pins 18, 21 and 23) vary, pressing cont, bright key? Yes

No

16 43.2 V (IC103, #3)

Replace IC101.

16

Does IC103's output (Pins 1, 2 and 3) vary, pressing cont, bright key? Yes

No

Replace IC103.

CH1 P-P = 43.2 V

CH1 RMS = 63.56 V

Check and replace Q101R, Q101G, Q101B, Q102R, Q102G, Q102B, Q103R, Q103G, Q103B.

DP14L*/DP15L*

6-17

6 Troubleshooting

6-2-16 No Video
Check signal cable connection. Check Cont, Bright key (All max).

Is heater voltage (5.9~6.3V) on SK103's heater Pin? Yes

No

Are D612, Q603 and R618 ok?

No

Replace it.

Yes Is 0V on Q604's collector? No Check and replace Q603, R618, R619.

Yes Is 5V on IC201's Pin 6 No Check and replace IC201.

Yes Check and replace Q604, R622.

17

Is G1 voltage OK at SK103's G1 Pin? Yes Check CN103's connection (G2).

No

Check and replace C119, D504, D505, Q501, R515, R516, R517, SK102.

WAVEFORMS
17 35.2 V (SK103, G1)

CH1 P-P = 35.2 V

CH1 RMS = 80.84 V

Desoldering SK101 and C118, is G2 voltage ok? Yes Is 12 V on IC101's Pins 1 and 7?

No

Check and replace SK101, C118 and then T501.

No

Opening BD102, is it short between IC101's Vcc and ground? Yes Replace IC101.

No

Refer to 6-2-1 No Power.

Yes

15

Is IC101's output on Pins 18, 21 and 23?

No

18

Is clamp signal on IC101's Pin 12?

No

Check and replace IC201 and around it.

6-18

DP14L*/DP15L*

6 Troubleshooting

6-2-16 No Video Continued
Is IC101's output on Pins 18, 21 and 23? Yes No Is clamp signal on IC101's Pin 12? Yes Refer to 6-2-15 ABL Failure. No Check and replace IC201 and around it.

15

18

Replace IC101.

16

Is IC103's output on Pins 1, 2 and 3? Yes

No

Is 70 V on IC103's Pin 4?

No

Check 70 V line.

Yes Replace IC103.

Are there waveforms on SK103's R, G, B? No Disconnect Video PCB from CRT neck.

Yes

Check again cont, bright key. 6.3 V line, G1, G2 line. Is it ok? Yes

19

Are ther waveforms on SK103's R, G, B? No

Yes

Check and replace SK103 and CRT.

Check and replace Q101R, Q101G, Q101B, Q102R, Q102G, Q102B, D103R, D103G, D103B and PCB pattern.

WAVEFORMS
15 3.16 V (IC101, #21) 16 43.2 V (IC103, #3) 18 5.60 V (IC101, #12) 19 46.4 V (SK103, G)

CH1 P-P = 3.16 V

CH1 RMS = 1.008 V

CH1 P-P = 43.2 V

CH1 RMS = 63.56 V

CH1 P-P = 5.60 V

CH1 RMS = 4.908 V

CH1 P-P = 46.4 V

CH1 RMS = 38.16 V

DP14L*/DP15L*

6-19

6 Troubleshooting

6-2-17 Micom Failure
Check the connection of signal cable. If signal cable is disconnected, self raster (No Video, Bright Raster) appears.

Check H/V sync from PC or signal generator.

If there is no H/V sync, monitor is operated as DPMS mode.

Check if timing is out of spec or not.

If out of sepc, monitor is operated as stand-by mode. (No Video, LED: 0.5 sec toggle) 14": Horizontal 30 ~ 55 kHz, Vertical 50 ~ 120 Hz 15": Horizontal 30 ~ 61 kHz, Vertical 50 ~ 120 Hz

Key check (all key) : Refer to 6-2-19.

Is 5V on IC201's Pins 11 and 34?

No

Is 13 V on C624?

No

Refer to 6-2-1 No Power.

Yes

Yes Check and replace IC602.

20

Are oscillation (8 MHz) on IC202's Pins 13 and 14? Yes Check reset part. Are IC202 ok? Yes

No

Check and replace C203, C204, X201.

WAVEFORMS
20 4.92 V (IC201, #14)

No

Replace it.
CH1 P-P = 4.92 V CH1 RMS = 2.912 V

24 25

Are H/V sync input on IC201's Pins 30 and 31?

Yes

When disconnecting signal cable: Is 0V on IC201's Pin 19? When connecting signal cable: Is 5V on IC202's Pin 13?

No

Cceck and replace IC201, R226.

6-20

DP14L*/DP15L*

6 Troubleshooting

6-2-17 Micom Failure Continued
Yes When disconnecting signal cable: Is 0V on IC201's Pin 19? When connecting signal cable: Is 5V on IC201's Pin 19? Yes Sus (Pin 5) : 5 V, Off (Pin 6) : 5 V? Yes LED is ok? No Check D202, D203. Yes Check PCB pattern to Pins 30 and 31. Check PCB pattern to IC401's Pins 1 and 2. Yes Yes Replace IC201. Refer to 6-2-13 I2C Failure. No
26 27

24 25

Are H/V sync input on IC201's Pins 30 and 31? Yes Check signal cable. Yes

No

Cceck and replace IC201, R226 Signal cable.

Yes

Replace LED. Are H/V sync input from IC201 on IC401's Pins 1 and 2?

WAVEFORMS
24 5.28 V (IC201, #31) 25 4.96 V (IC201, #30) 26 5.48 V (IC401, #1) 27 4.48 V (IC401, #2)

CH1 P-P = 5.28 V

CH1 RMS = 1.218 V

CH1 P-P = 4.96 V

CH1 RMS = 350 mV

CH1 P-P = 5.48 V

CH1 RMS = 1.362 V

CH1 P-P = 4.48 V

CH1 RMS = 284 mV

DP14L*/DP15L*

6-21

6 Troubleshooting

6-2-18 Key Check
1) Key Map
Keyout3 (#5) Keyout2 (#4) Keyout1 (#3) Keyin4 (#39) Keyin3 (#40) Keyin2 (#42) Keyin1 (#1)

R206

R207

R208

R209

SW204 (V-Size)

SW203 (H-Size)

SW202 (V-Posi)

SW201 (H-Posi)

SW208 (Cont)

SW207 (Brit)

SW206 (Trap)

SW205 (S-Pin)

SW209 (Up)

SW210 (Down)

2) Voltage Check of Keyin and Keyout Press the key what you want to check. At that moment, the voltage of keyin and keyout that is connected with together should be changed as follows. Normal Keyout Keyin 5V 0V Pressed CH1 of Picture Pin 21 CH2 of Picture Pin 21 RMS voltage 0.7 ~ 0.9 V 0.7 ~ 0.9 V

3) LED Check Pressing key, LED should be blinked. 4) How to Repair? If only one key has a key problem, replace that key. But if some keys that are connected with same keyin or keyout line have problems, check and replace PCB pattern and IC201.

WAVEFORMS
21 5.52 V (IC201, Keyout) 21 5.44 V (IC201, Keyin)

CH1 P-P = 5.52 V

CH1 RMS = 3.696 V

CH1 P-P = 5.44 V

CH1 RMS = 1.436 V

6-22

DP14L*/DP15L*

6 Troubleshooting

6-2-19 User Control Failure
When pressing keys, does LED blink? Yes Refer to 6-2-18 Key Check. Refer to 6-2-18 Key Check. No Check knob function and space at front cover.

6-2-20 Degaussing Failure
Check if degaussing coil is connected with GT601, GT602.

When pressing cont and brit key simultaneously, does the voltage of IC201's Pin 4 vary from 0 V to 5 V for 2~3 seconds? Yes Check and replace D616, Q601, R603, RL601.

No

Refer to 6-2-18 Key Check.

Check and replace degaussing coil.

DP14L*/DP15L*

6-23

6 Troubleshooting

6-2-21 Horizontal Blank Failure
Symptoms: Dark image and if shifting image to left or right side, image is rolled. Raster left or right side is rolled.

31

Is H_Blank waveform on Q510's collector? No

Yes

WAVEFORMS
Check CN105 and CN202.
31 5.36 V (Q510, Collector)

Check and replace IC101.
CH1 P-P = 5.36 V CH1 RMS = 4.210 V

Are Q504 and D515 ok?

No

Replace it.

Yes Check and replace C501, C502, C503, R504.

6-2-22 Whistle Sound
Check trans coil (L401, T501, T601, CRT)

6-2-23 Spot at Center During Power Off
Does G1 voltage vary from 60~80 Vrms to 200 Vrms during power off time? (After falling down to 200V, G1 voltage is slowly increased to 0V). No Are 12 V line and Q501 ok? No Replace it.
CH1 P-P = 158 V CH1 RMS = 151.1 V

WAVEFORMS
Yes Check and replace CRT.
32 158 V (CN105, G1)

32

Yes Check and replace C506, D504, R515, R516, R517.

6-24

DP14L*/DP15L*