Samsung AQ15VS Troubleshooting

5 Troubleshooting

5-1 Parts Level Troubleshooting

Notes: Check the following circuits.

• No raster appears: Power circuit, Horizontal output circuit.

• High voltage develops but no raster appears: Video output circuits.

• High voltage does not develop: Horizontal output circuits.

5-1-1 No Power Supply

Check and replace D601 and FH1

Chirping noise exists?

No

Repeating start?

No

1

IC601 Pin 1 waveform is right?

Yes

C622 Voltage is 13 V ± 0.5V?

Yes

Yes

No

No

Check and replace IC601.

Check and replace D606.

Check and replace D614, IC601,

Q602 and ZD601.

Check and replace IC201, IC301,

IC401, Q402, Q404,

IC603, Q609,and Q611.

WAVEFORMS

100 V (IC601, #1)

1

CH1 P-P = 100 V CH1 RMS = 350.2 V

Yes

Operate normally?

Yes

Verify voltages.

Done.

AQ15VS/AQ15HS 5-1

No

Replace Main board.

5 Troubleshooting

5-1-2 DPMS Failure

Check signal source

H/V Sync. video level.

Make No H/V Sync.

(power off mode)

LED blinks?

+12 V line off?

2

IC601 Pin 1 output

voltage exists?

Yes

Yes

No

No

No

Check IC201 Pin 40.

Check IC201 Pin 6.

Refer to 5-1-1 No Power Supply.

WAVEFORMS

100 V (IC601, #1)

2

CH1 P-P = 100 V CH1 RMS = 325.8 V

Done

Yes

5-2 AQ15VS/AQ15HS

5-1-3 H_Deflection Failure

5 Troubleshooting

Does PWM output signal appear

3

at Pin 28 (B_out) of IC401?

Yes

Does Horizontal pluse signal

4

appear at at Pin 26 of IC401?

Yes

Does 20 Vp-p signal appear

5

at Collector of Q418?

Yes

Check Q402, Q404 and T401.

No

No

No

Does DC 12V appear at

Pin 29 of IC401?

Yes

Check IC401.

Check IC401.

Check Q418.

No

Check 12 V line.

WAVEFORMS

5.00 V (IC401, #28)

3

1.00 V (IC401, #26)

4

5-1-4 S Correction Failure

Check S1 ~ S3 signal.

S1~S3 signals are right at each

frequency block?

Yes

Check and replace Q404, Q410, Q411,

(Q409, Q414 : HT/HO)

Q415, and Q416.

No

Check and replace IC201.

5.00 V (Q418, Collector)

5

AQ15VS/AQ15HS 5-3

5 Troubleshooting

5-1-5 H_Lin. Failure

IC201 Pin 21 voltage varies with

different H_Lin. DAC values?

Yes

IC603 Pin 14 voltage varies with

different H_Lin. DAC values?

Yes

Check Q412, Q413 and T402.

5-1-6 Invariable H_Size

IC401 Pin 28 voltage varies with

different B_OUT DAC values?

Yes

No

No

No

Replace IC201.

Check +13 V_1, Coil

Check some parts around IC603.

Check and replace IC401.

_

5 V line.

Q402 Gate output duty varies with

different B_OUT DAC values?

5-1-7 Abnormal H_Size

IC401 Pin 24 output duty

varies with different B+ offset

DAC values?

Yes

Q408 Collector waveform is

6

around D409 and L401.

right?

Yes

Check some parts

No

No

No

Check some parts around Q402,

IC401 Pin 4 ~ 6.

Check and replace IC201.

Check and replace Q405,

Q406, Q407, and Q408.

WAVEFORMS

5.00 V (Q408, Collector)

6

5-4 AQ15VS/AQ15HS

5-1-8 Side Pin or Trap Failure

5 Troubleshooting

7

IC401 Pin 24 output exists?

Yes

Refer to 5-1-7

Abnormal H_Size

.

5-1-9 Para. or Pin Balance Failure

IC401 Pin 24 output varies with

different DAC values?

No

Replace IC401.

No

Yes

Check and replace IC401.

Refer to 5-1-7

Abnormal H_Size

WAVEFORMS

1.00 V (IC401, #24)

7

.

5-1-10 Tilt Failure

Check tilt connector connection

IC201 Pin 20 output duty varies

with different DAC values?

Yes

IC603 Pin 3 output varies with

different DAC values?

Yes

Check and replace Q301 and Q302.

No

Check and replace IC201.

No

Check and replace IC603.

AQ15VS/AQ15HS 5-5

5 Troubleshooting

5-1-11 V Deflection Failure

13V and –10V lines are on?

Yes

IC401 Pin 23 output exists?

8

Yes

9

IC301 Pin 6 output exists?

Yes

Check DY connector connection.

No

No

No

Refer to 5-1-1 No Power Supply

Check and replace IC401.

Check and replace some parts

around IC301.

WAVEFORMS

1.00 V (IC401, #12)

8

10.0 V (IC301, #6)

9

5-1-12 V Size or Position Variation Failure

IC401 Pin 23 output varies with

different DAC values?

Yes

Check and replace IC301.

No

Check and replace IC201 and IC401.

5-6 AQ15VS/AQ15HS