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7 Troubleshooting
7-1 Parts Level 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.
7-1-1 No Power Supply
Check and replace FH1, D602, D603, D604, D605.
WAVEFORMS
1 544 V (IC601, #1)
Chirping noise exists?
Yes
Check and replace IC601.
No Repeating start? Yes Check and replace D607.
CH1 P-P = 544 V
CH1 RMS = 332.4 V
No
1
IC601 Pin 1 waveform is right?
No
Check and replace OP601, IC603, D610, D624, D609.
Yes OP601, IC603, D610 are right? No Replace parts and verify voltages.
Yes Normal operation No Replace Main board.
Yes Verify voltages.
Yes Done.
CHB5**7L/6**7L/7**7L
7-1
7 Troubleshooting
7-1-2 DPMS Failure
Check signal source H/V sync video level.
WAVEFORMS
2 544 V (IC601, #1)
Make No H/V sync (power off mode)
CH1 P-P = 544 V CH1 RMS = 332.4 V
LED blinks
No
Check IC201 Pin 20.
Yes +12 V line off No Check IC201 Pin 41.
Yes Q622, Q621 Base driving voltage exists? Yes
2
No
Check IC201 Pin 40. Check and replace Q622, Q621.
IC601 Pin 1 output voltage exists? Yes Done
No
Refer to 7-1-1 No Power Supply.
7-2
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-1-3 H_Deflection Failure
Does PWM output signal appear at Pin 26 (H_out) of IC401? Yes No Does DC 5 V appear at Pin 32 of IC401? Yes No Check 5 V, 12 V line.
3
WAVEFORMS
Check IC401.
3 8.80 V (IC401, #26)
Does 12 Vp-p signal appear at Emitters of Q441 and Q442? Yes
4
No
Check Q441 and Q442.
CH1 P-P = 8.80 V CH1 RMS = 6.176 V
4 104.0 V (T401, #1)
Does 110 Vp-p signal appear at Pin 5 of T401? No
No
Check Q443.
Check CN443, D442, Q443 and T402.
CH1 P-P = 104.0 V
CH1 RMS = 51.84 V
7-1-4 S Correction Failure
Check S1 ~ S3 signal.
S1~S3 signals are right at each frequency block? Yes Check and replace Q461 ~ Q463, C461 ~ C465.
No
Check and replace IC201.
CHB5**7L/6**7L/7**7L
7-3
7 Troubleshooting
7-1-5 H_Lin. Failure
IC201 Pin 33 voltage varies with different H_Lin. DAC values? Yes IC302 Pin 14 voltage varies with different H_Lin. DAC values? Yes Check Q471, Q472, T403. No Check +12 V, 10 V line. Check some parts around IC302. No
Replace IC201.
7-1-6 Invariable H_Size
IC401 Pin 28 voltage varies with different B_Out DAC values? Yes Q433 Gate output duty varies with different B_Out DAC values? No Check some parts around Q433, IC401 Pin 28. No
Check and replace IC401.
7-1-7 Abnormal H_Size
IC401 Pin 24 output duty varies with different B+ offset DAC values? Yes
5
No
Check and replace IC201. Check some parts IC201 Pins 12 and 16, IC201 Pin 23.
WAVEFORMS
5 26.4 V (T402, #10)
T402 Pin 10 waveform is right?
No
Check and replace T402.
CH1 P-P = 26.4 V CH1 RMS = 7.02 V
Yes Check some parts around D432.
7-4
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-1-8 Side Pin or Trap Failure
No
WAVEFORMS
Check and replace IC401.
6 720 mV (IC401, #24)
6
IC401 Pin 24 output exists?
Yes Check some parts around IC401 Pins 15 and 16.
CH1 P-P = 720 mV CH1 RMS = 2.792 V
7-1-9 Para. or Pin Balance Failure
IC401 Pin 4 output varies with different DAC values? No Replace IC401.
7-1-10 Tilt Failure
Check tilt connector connection
IC201 Pin 21 output duty varies with different DAC values? Yes IC302 Pin 1 output varies with different DAC values? Yes Check and replace CRT.
No
Check and replace IC201.
No
Check and replace IC302.
CHB5**7L/6**7L/7**7L
7-5
7 Troubleshooting
7-1-11 V Deflection Failure
No
WAVEFORMS
Refer to 7-1-1 No Power Supply
7 3.40 V (IC401, #23)
13 V, 10 V line is on?
Yes
7
IC401 Pin 23 output exists?
No
Check and replace IC401.
CH1 P-P = 3.40 V CH1 RMS = 3.756 V
Yes
8
8 46.4 V (IC301, #5)
IC301 Pin 5 output exists?
No
Check and replace some parts around IC301.
Yes Check V DY connector connection.
CH1 P-P = 46.4 V
CH1 RMS = 6.30 V
7-1-12 V Size or Pos. Variation Failure
IC401 Pin 23 output varies with different DAC values? Yes Check and replace IC401 and IC301. No
Check some parts around IC301. Check bias voltage.
7-6
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-1-13 High Voltage Failure
No
WAVEFORMS
Check and replace IC501 and +12 V line.
10 12.16 V (IC501, #5)
10
IC501 Pin 5 OSC pulse exists?
Yes
11
Q502 Gate driving pulse exists?
No
Check and replace Q509, Q501 and D504.
CH1 P-P = 12.16 V CH1 RMS = 6.376 V
Yes Q504 Gate driving pulse exists? No Check and replace Q503, Q441 ~ Q443.
11 9.12 V (Q502, Gate)
Yes Done
CH1 P-P = 9.12 V
CH1 RMS = 3.736 V
7-1-14 ABL Failure
Input full white pattern to monitor.
IC101 Pin 12 input exists and varies with different patterns? No Check CN104. No T501 Pin 8 output exists?
Yes
Check and replace IC101.
No
Check and replace T501.
Yes IC201 Pin 35 output exists and varies with different patterns? Yes Check and replace Q506. No Check and replace IC201.
CHB5**7L/6**7L/7**7L
7-7
7 Troubleshooting
7-1-15 Dynamic Focus Failure
IC401 Pin 10 output is right? No
WAVEFORMS
Replace the IC401.
12 720 mV (IC401, #10)
12
Yes Some parts around Q551 are right? No Replace failed part.
CH1 P-P = 720 mV CH1 RMS = 2.710 V
Yes
13
13 50.8 V (T502, #6)
T502 Pin 6 input is right?
No
Check and replace C556.
Yes
CH1 P-P = 50.8 V CH1 RMS = 16.56 V
14
T502 Pin 1 output is right?
No
Replace the T502.
14 360 V (T502, #1)
No Check the connection between FBT Pin 8, CRT Socket PCB.
CH1 P-P = 360 V
CH1 RMS = 114.4 V
7-8
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-1-16 No Video
Check signal cable and connection.
WAVEFORMS
15 780 mV (IC101, #5, 8, 10)
15
IC101 Pins 5, 8 and 10 inputs are right? Yes
No
Check the signal cable connection.
CH1 P-P = 780 mV
CH1 RMS = 2.494 V
16
IC101 Pins 21, 24 and 26 outputs are right? Yes
No
16 2.72 V (IC101, #21,24,26)
Check I2C bus and +12 V line.
17
IC102 Pins 1, 3 and 5 outputs are right? Yes Cathode DC levels are right?
No
Check +12 V line. Check and replace IC102.
CH1 P-P = 2.72 V
CH1 RMS = 13.78 V
17 34.4 V (IC102, #1, 3, 5)
No
Check +75 V line. Check and replace QR01, QR02, QG01, QG02, QB01, QB02.
CH1 P-P = 34.4 V CH1 RMS = 44.52 V
Yes G2 voltage is right? No Check G2 wire, CRT Socket board, and FBT.
Yes Change CRT.
Done.
CHB5**7L/6**7L/7**7L
7-9
7 Troubleshooting
7-1-17 Micom Failure
No
WAVEFORMS
Check IC604.
18 5.00 V (IC201, #6, 7)
IC201 Pin 5 input is right?
Yes
18
IC201 Pins 6 and 7 inputs are right? Yes IC201 Pin 2 input is right?
No
Check X201, C206 and C207.
CH1 P-P = 5.00 V CH1 RMS = 2.966 V
No
Check IC202.
Yes All in/output values are right? No Replace IC201.
No Done
7-10
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-1-18 OSD Failure
Check CN104 and connector Ass'y.
WAVEFORMS
19 4.92 V (IC104, #10)
19
IC104 Pin 10 input is right?
No
Check and replace Q103. Check CN104 Pin 15.
CH1 P-P = 4.92 V CH1 RMS = 5.072 V
Yes
20
IC104 Pin 5 input is right?
No
Check and replace Q102. Check CN104 Pin 13.
20 4.84 V (IC104, #5)
Yes IC104 Pins 7 and 8 inputs are right? Yes IC104 Pins 13, 14 and 15 outputs are right? No IC101 Pins 21, 24 and 26 outputs are right? Yes Check and replace IC102. No Check and replace IC101. No Check and replace IC104. No Check IC201 Pins 12 and 16.
CH1 P-P = 4.84 V CH1 RMS = 4.222 V
Done
CHB5**7L/6**7L/7**7L
7-11
7 Troubleshooting
7-1-19 User Control Failure
Does the DC level change at Pins 38 and 39 of IC201 when you push the push button S/W? Yes Check IC201. No Check the button. (SW201 ~ SW203)
7-1-20 Degaussing Failure
Check degaussing connector.
RL601 operation is right?
Yes
Check D-coil and TH601.
No Q601 base input is right? Yes Check and replace Q601.
No IC201 Pin 24 output is right? No Check and replace IC201.
Yes Done
7-12
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-2 General Troubleshooting
7-2-1 No Picture
Yes
LED blinks?
Refer to 7-2-2 Shut down.
No LED is green color? No Check Micom.
Yes Check G2 voltage, high voltage, R, G, B cathode voltage.
7-2-2 Shut Down
Blinking LED's?
No
Check power supply.
Yes Scan failure Yes Check horizontal, vertical deflection system and check power supply secondary voltages.
No High voltage failure? Yes Check high voltage system.
No Video failure? Yes Check Video board.
No Check and replace IC201.
Done
CHB5**7L/6**7L/7**7L
7-13
7 Troubleshooting
7-2-3 Missing Color
Are proper Video levels on CN101 (D-Sub) Pins 1, 3 and 5, R-BNC, G-BNC and B-BNC? Yes Are proper AC voltage on all cathodes? Yes Are proper DC voltage on all cathodes? Yes Is G2 voltage right?
No
Check signal generator and cathode.
No
Refer to 7-1-16 No Video.
No
Check IC101 Pins 15, 16 and 17. Check QR01, QR02, QG01, QG02, QB01 and QB02.
No
Check G2 wire, G2 control, volume and FBT.
Yes Change the CRT.
Done
7-14
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-2-4 Visible Retrace
Check white balance adjustment.
Is G2 voltage right?
No
Check G2 control volume and FBT.
Yes Is blank pulse on Pin 19 of IC101 on Video board? Yes Is blank pedestal on Pins 21, 24 and 27 of IC101? Yes Is V_FLB pulse on Pin 15 of CN104? Yes Is blank pedestal on all cathodes? No Check IC101 and Pins 1, 3 and 5 of IC102. Check QR01, QR02, QG01, QG02, QB01 and QB02. No Check Q331. No Check IC101 and related components. No Check Q102, CN104 and T402 Pin 10.
Yes Done
CHB5**7L/6**7L/7**7L
7-15
7 Troubleshooting
7-2-5 Unsynchronized Image
Check input signals Pins 9 and 11 of CN101.
Are signals right?
No
Check Video cable.
Yes Signals at Pins 3 and 4 of CN104 are right? Yes Signals at CN102A Pins 3 and 6 on Main board are right? Yes Check circuits on Main board. (IC201 and X201) No Check Video and Main board. No Check ZD103 and D106 on Video board.
Done
7-16
CHB5**7L/6**7L/7**7L
7 Troubleshooting
7-2-6 Misconvergence
Try readjusting convergence.
Is the convergence now within spec? No Readjust convergence.
Yes
Done
Is the convergence now within spec? No Change CRT and readjust convergence.
Yes
Done
Done
CHB5**7L/6**7L/7**7L
7-17
7 Troubleshooting
7-2-7 Poor Focus
Adjust focus VR.
Improved focus?
Yes
Aging monitor and check for focus change.
No Check focus leads from FBT to CRT Socket.
Check the CRT Socket.
Is dynamic focus circuit right?
No
Refer to 7-1-15 Dynamic Focus Failure.
Yes Replace the CRT and verify focus.
7-2-8 Purity Failure
Degaussing
Purity is right?
Yes
Done
No Degaussing circuit is right? No Refer to 7-1-20 Degaussing Failure.
Yes Replace CRT and verify purity.
7-18
CHB5**7L/6**7L/7**7L