Samsung CKG7507 Troubleshooting

CKG7507L 7-1

7 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.

Check the Fuse, Bridge Diodes (D601~D604),

IC601, C617 and D614.

Check the Q503, Q504 and those are related High

Voltage control circuits. (IC501, Q510, Q501,

Q502, Q506, D508, D517 and D524)

7-1 No Power

Does proper DC 110-366 Volts

appear between the positive and

negative poles of C606?

Does the appear 45V at D617’s

Cathode pin? (the condition L501’s

are pin is desoldered)

Yes

Check D605, C616, C618, components in primary

part, the power feedback circuit (IC602, IC603,

and its related circuits), D617, D618, D610, D615,

D612, D620, D619, IC606 and IC607.

Does the appear 2’nd voltage

of T601 (45V, 72V, 14.7V and so on)?

(The condition BD602, BD603,

JW71, JW63 are desoldered)

Yes

Check the Q406, Q403, Q411 and those are

related Horizontal control circuit. (IC401, IC402,

Q404, Q401, Q402, Q405, Q408 and Q409)

Does the appear 45V at D617’s

Cathode pin? (the condition L403’s

are pin is desoldered)

Yes

Replace the IC301.

Does the appear 45V at D617’s

Cathode pin? (the condition

JW71, JW63 are desoldered)

Yes

Check the IC102, IC101 and another components

in Video Part (IC103, IC104, etc).

Does the appear 45V at D617’s

Cathode pin? (the condition

CN102 is disconnected)

7 Troubleshooting

7-2 CKG7507L

7-3 Vertical Line on CRT

Does the drive pulse

appear at the emitter of

Q401?

Yes

Replace Q403 or check its

related circuits.

(C416 and T401)

WAVEFORMS

Check Q411 and D408.

Does the drive output

pulse appear at the Collector

of Q403?

Yes

Check IC402 and its application.

Does the pulse appear at

Gate of Q411?

Yes

Replace IC301 and check its related

Vertical IC’s application.

Check the –12V Line at power

secondary part. (D615, C620)

Check R303 and R310.

Replace IC401.

7-2 Horizontal Line on CRT or Rainbow Color on the Screen

The first of all you must check

CN301. Does the –12V appear at

Pin 4 of IC301?

Does the pulse appear at Pin 5

of IC301?

Yes

Does the sawteeth wave appear

at the Pin 9 of IC401?

WAVEFORMS

15.8 V (Q411, Gate)

CH1 P-P = 15.8 V CH1 RMS = 8.37 V

54.8 V (IC301, #5)

CH1 P-P = 54.8 V CH1 RMS = 6.38 V

2.80 V (IC401, #9)

CH1 P-P = 2.80 V CH1 RMS = 3.469 V

140 V (Q403, Collector)

CH1 P-P = 140 V CH1 RMS = 52.7 V

7.12 V (Q401, #Emitter)

CH1 P-P = 7.12 V CH1 RMS = 4.836 V

7 Troubleshooting

CKG7507L 7-3

Change FBT.

Check the power supply circuits.

Power indicator is green

Check Q404 and its related circuits.

Does the +B output voltage

appear at the secondary side of

T601? (45 V, 72 V, 14.7 V, etc)

Does the output

pulse appear at

Pin 18 of IC401?

Check IC501 and its application

circuits.

Does the pulse appear at

the Collector of Q503?

7-4 No Raster (1)

Yes

Does the DC Voltage (about 10V)

appear at Pin 7 of IC502?

Yes

Replace IC502.

Check HV protection circuits and

IC502’s application circuits.

WAVEFORMS

Does the DC Voltage

(200V over) appear at HV_ADJ

point (The condition Pin 7 of IC502

is desoldered)?

8.56 V (IC401, #18)

CH1 P-P = 8.56 V CH1 RMS = 5.900 V

856 V (Q503, Collector)

CH1 P-P = 856 V CH1 RMS = 251.2 V

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