Samsung PN19MT-MO-IO, PN19MT9U 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 FG601, D601, D701, Q701, IC601, and ZD601.

Yes

Repeating start?

Yes

1 IC601 Pin 1 waveform is right?

Yes

IC701 Pin 8 Voltage is right?

Yes

Operate normally?

Yes

Verify voltages.

WAVEFORMS

1 100 V (IC601, #1)

Check and replace D606, IC620,

D647, and D640.

CH1 P-P = 100 V

CH1 RMS = 350.2 V

Check and replace

D620, IC601 and IC701.

Check and replace ZD705, ZD706, D702, and also check the secondary diodes.

Replace Main board.

Done.

PN19MT/MO/IO	5-1
x178/19P2

5 Troubleshooting

5-1-2 DPMS Failure

Check signal source

H/V Sync. video level.

Make No H/V Sync. (power off mode)

No

Check IC201 Pin 39.

	Q620 Base drive voltage?			No	Check IC201 Pin 10.
					Check and Replace Q403.
		Yes
				No
	Is there 12 volt?				Check IC201 Pin 9.
					Check IC651.
		Yes
	Done

5-2	PN19MT/MO/IO
	x178/19P2

5-1-3 H_Deflection Failure

3 Q454 Drain waveform is right?

Yes

2 4

			Yes
		Q402 Collector waveform
	5
		is right?

	No	Check R467, Q454, D456,
		and +210V line.
		Check ZD450 and IC402 Pin 6

No

Check IC250.

	No	Check IC250 Pin 26.
		Check Q401, R404 and 25V line.
		Check Q250, Q251.

No	Check and replace D403 and Q402.
	Check DY connector connection.

5 Troubleshooting

2 13.0 V (Q401, Gate)

CH1 P-P = 13.0V	CH1 RMS = 7.91V

3 210 V (Q454, Drain)

CH1 P-P = 210V	CH1 RMS = 302V

4 66.4V (Q401, Drain)

CH1 P-P = 66.4V	CH1 RMS = 25.84V

5 1.24kV (Q402, Collector)

CH1 P-P = 1.24kV CH1 RMS = 302V

6 11.0V (IC250, #26)

CH1 RMS = 11.0V

PN19MT/MO/IO	5-3
x178/19P2

5 Troubleshooting

7-1-4 S Correction Failure

Check S1 ~ S3 signal.

S1~S3 signals are right at each	No	Check and replace IC201.
frequency block?

Yes

Check and replace C411~C418,

Q408~Q411, Q403~Q407.

5-1-5 H_Lin. Failure

IC201 Pin 21 voltage varies with different H_Lin. DAC values?

Yes

IC403 Pin 7, 8 voltage varies with different H_Lin. DAC values?

Yes

Check L403.

No

Replace IC201.

No	Check+12V line.

Check some parts around IC403.

5-1-6 Invariable H_Size

IC201 Pin 20 voltage varies with different B_Out DAC values?

			Yes
		IC402 Pin6 Voltage Varies with
	7
		different H_Lin. DAC Values?

No

Check and replace IC201.

No

Check and replace IC402.

WAVEFORMS

7 13.6 V (IC402, #6)

CH1 P-P = 13.6V	CH1 RMS = 9.02V

5-4	PN19MT/MO/IO
	x178/19P2

5 Troubleshooting

5-1-7 Abnormal H_Size

WAVEFORMS

	T402 Pin 8 waveform is right?	No	Check and replace T402.
8

Yes

Check IC402 Pin 6

and IC201 Pin 20 and 22.

8 28.0V (T402, #8)

CH1 P-P = 28.0V	CH1 RMS = 5.92V

5-1-8 Side Pin or Trap Failure

WAVEFORMS

	IC250 Pin 24 output exists?	No
9			Check and replace IC250.
					9		IC250, #24

CH1 P-P = 1.00V

CH1 RMS = 3.008 V

5-1-9 Para. or Pin Balance Failure

IC250 Pin 24 output varies with

9

different DAC values?

Yes

Replace IC250.

PN19MT/MO/IO	5-5
x178/19P2

5 Troubleshooting

5-1-10 Tilt Failure

Check tilt connector connection

IC201 Pin 23 output duty varies with different DAC values?

Yes

IC403 Pin 10, 11 output varies with different DAC values?

Yes

Check and replace CRT.

No

Check and replace IC201.

No

Check and replace IC403.

5-1-11 V Deflection Failure

No

14V line is on?

Yes

No

10 IC250 Pin 23 output exists?

Yes

No

IC301 Pin 1 output exists?

Yes

No

11 IC301 Pin 6 output exists?

Yes

Check V_DY connector connection.

Refer to 5-1-1 No Power Supply

Check and replace IC250.

Check and replace R301.

Check and replace some parts around R312, R316 and IC301.

WAVEFORMS

10 1.32 V (IC250, #23)

CH1 P-P = 1.32V	CH1 RMS = 1.507 V

11 55.2 V (IC301, #6)

CH1 P-P = 55.2 V CH1 RMS = 8.04 V

5-6	PN19MT/MO/IO
	x178/19P2