Samsung CHB7227, CHB5237, CHB7709, CHB7707, CHB5707 Troubleshooting

CHB5**7L/6**7L/7**7L 7-1

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

Chirping noise exists?

Check and replace IC601.

Check and replace FH1, D602,

D603, D604, D605.

Done.

No

Yes

Repeating start?

Check and replace D607.

No

Yes

IC601 Pin 1 waveform is right?

Check and replace OP601, IC603,

D610, D624, D609.

Yes

No

OP601, IC603, D610 are right?

Replace parts and verify voltages.

Yes

No

Normal operation

Replace Main board.

Yes

Verify voltages.

Yes

No

WAVEFORMS

1

1

544 V (IC601, #1)

CH1 P-P = 544 V CH1 RMS = 332.4 V

7 Troubleshooting

7-2 CHB5**7L/6**7L/7**7L

7-1-2 DPMS Failure

Make No H/V sync (power off

mode)

Check signal source

H/V sync video level.

LED blinks

Check IC201 Pin 20.

Yes

No

+12 V line off

Check IC201 Pin 41.

Yes

No

Q622, Q621 Base driving

voltage exists?

Check IC201 Pin 40.

Check and replace Q622, Q621.

Yes

No

IC601 Pin 1 output

voltage exists?

Refer to 7-1-1 No Power Supply.

Done

Yes

No

WAVEFORMS

2

2

544 V (IC601, #1)

CH1 P-P = 544 V CH1 RMS = 332.4 V

7 Troubleshooting

CHB5**7L/6**7L/7**7L 7-3

7-1-3 H_Deflection Failure

Does 12 Vp-p signal appear at

Emitters of Q441 and Q442?

Check Q441 and Q442.

Yes

No

Does 110 Vp-p signal appear

at Pin 5 of T401?

Check Q443.

No

No

Check CN443, D442, Q443 and T402.

WAVEFORMS

4

3

8.80 V (IC401, #26)

CH1 P-P = 8.80 V CH1 RMS = 6.176 V

4

104.0 V (T401, #1)

CH1 P-P = 104.0 V CH1 RMS = 51.84 V

Does PWM output signal appear

at Pin 26 (H_out) of IC401?

Check IC401.

Check 5 V, 12 V line.

Yes

No

Does DC 5 V appear at

Pin 32 of IC401?

Yes

No

3

7-1-4 S Correction Failure

S1~S3 signals are right at each

frequency block?

Check S1 ~ S3 signal.

Check and replace Q461 ~ Q463,

C461 ~ C465.

Yes

Check and replace IC201.

No

7 Troubleshooting

7-4 CHB5**7L/6**7L/7**7L

7-1-5 H_Lin. Failure

IC201 Pin 33 voltage varies with

different H_Lin. DAC values?

IC302 Pin 14 voltage varies with

different H_Lin. DAC values?

Check +12 V, –10 V line.

Check some parts around IC302.

Check Q471, Q472, T403.

Yes

Yes

No

Replace IC201.

No

7-1-6 Invariable H_Size

IC401 Pin 28 voltage varies with

different B_Out DAC values?

Q433 Gate output duty varies with

different B_Out DAC values?

Check some parts around Q433,

IC401 Pin 28.

Yes

No

Check and replace IC401.

No

7-1-7 Abnormal H_Size

IC401 Pin 24 output duty

varies with different B+ offset

DAC values?

T402 Pin 10 waveform is right?

Check and replace T402.

Check some parts around D432.

Yes

Yes

No

Check and replace IC201.

Check some parts IC201 Pins 12

and 16, IC201 Pin 23.

No

WAVEFORMS

5

5

26.4 V (T402, #10)

CH1 P-P = 26.4 V CH1 RMS = 7.02 V

7 Troubleshooting

CHB5**7L/6**7L/7**7L 7-5

7-1-8 Side Pin or Trap Failure

IC401 Pin 24 output exists?

Yes

Check and replace IC401.

Check some parts around IC401

Pins 15 and 16.

7-1-9 Para. or Pin Balance Failure

IC401 Pin 4 output varies with

different DAC values?

No

Replace IC401.

No

WAVEFORMS

6

6

720 mV (IC401, #24)

CH1 P-P = 720 mV CH1 RMS = 2.792 V

7-1-10 Tilt Failure

IC201 Pin 21 output duty varies

with different DAC values?

IC302 Pin 1 output varies with

different DAC values?

Check and replace IC302.

Check and replace CRT.

Yes

Yes

No

Check and replace IC201.

No

Check tilt connector connection

7 Troubleshooting

7-6 CHB5**7L/6**7L/7**7L

7-1-11 V Deflection Failure

13 V, –10 V line is on?

IC401 Pin 23 output exists?

Check and replace IC401.

Yes

Yes

No

Refer to 7-1-1 No Power Supply

No

IC301 Pin 5 output exists?

Check and replace some parts

around IC301.

Yes

No

Check V DY connector connection.

WAVEFORMS

7

8

7

3.40 V (IC401, #23)

CH1 P-P = 3.40 V CH1 RMS = 3.756 V

8

46.4 V (IC301, #5)

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 some parts around IC301.

Check bias voltage.

Check and replace IC401 and IC301.

No