Samsung DP15LS Troubleshooting

DP14L*/DP15L* 6-1

6 Troubleshooting

6-1 General 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.

6-1-1 No Picture

Check signal cable connection, H/V Sync input.

Check Timing mode (14”: 30~55kHz, 15”: 30~61kHz).

Check Cont,

Bright

key (all Max) and Screen VR (G2).

Check key components of secondary part. :

D406, D407, D408, D515, Q402, Q410, Q504, Rectifier

diodes (D608 ~ D612), IC101 (Vcc~GND)

Check key components of primary part. :

D601 ~ D607, FH601, IC601, TH602

Check SW601 (Power key)

Refer to 6-2-16 No Video.

Refer to 6-2-1 No Power.

Refer to 6-2-3 No Raster and 6-2-12 High Voltage Failure.

Refer to 6-2-17 Micom Failure.

Refer to 6-2-13 I2C Failure.

6 Troubleshooting

6-2 DP14L*/DP15L*

6-1-2 Shut Down

Check X-ray protection circuit. :

D502, D503, R510

Check key components of secondary part. :

D406, D407, D408, D515, IC101 (Vcc ~ GND)

Q402, Q504, Rectifier diodes

Check and replace IC601.

Refer to 6-2-1 No Power.

Refer to 6-2-3 No Raster and 6-2-12 High Voltage Failure.

Refer to 6-2-17 Micom Failure.

Refer to 6-2-13 I2C Failure.

6 Troubleshooting

DP14L*/DP15L* 6-3

6-1-3 No Video or Missing Colors

Are 0.7Vp-p video input on

CN202_2 R, G, B?

Check signal cable and generator.

Yes

No

Are proper waveform on

SK103’s R, G, B cathode?

Refer to 6-2-16 No Video.

Yes

No

Is G2 and heater voltage OK?

Check and replace SK103 and

some parts around it.

Yes

No

Change CRT and replace it.

Check white balance adjustment.

WAVEFORMS

22

19

19

46.4 V (SK103, G)

CH1 P-P = 46.4 V CH1 RMS = 38.16 V

22

1.016 V (CN202_2, #2,4,6)

CH1 P-P = 1.016 V CH1 RMS = 174.4 mV

WAVEFORMS

17

35.2 V (SK103, G1)

CH1 P-P = 35.2 V CH1 RMS = 80.84 V

25

4.96 V (IC201, #30)

CH1 P-P = 4.96 V CH1 RMS = 350 mV

Check signal cable connection, H/V Sync input.

Check Timing mode (14”: 30~55kHz, 15”: 30~61kHz).

Check Cont, Brit key (all Max) and Screen VR (G2).

6-1-4 Visible Retrace

Is G2 voltage (Screen VR) OK?

Adjust Screen VR to 0.4~0.6F/L (back

raster) at cont, bright all max.

Yes

No

Is V_sync input on Q301 base?

Check V_sync input line.

Yes

No

Is proper G1 pulse on SK103’s

G1 pin?

Check C306, C506, D504

Q301, Q501 and around parts.

Yes

No

Check and replace CRT.

25

17

6 Troubleshooting

6-4 DP14L*/DP15L*

6-1-5 Unsynchronized image

Are H/V sync input on IC201’s

Pins 30 and 31?

Check the connection of signal cable.

Refer to 6-2-12 High Voltage Failure.

Yes

Check H/V sync input line.

No

6-1-6 Misconvergence

Spec in?

(Center : 0.3 mm, Cornor : 0.4 mm)

Readjust Misconvergence.

Done

Yes

Change CRT and readjust

Miconvergence and color.

No

Refer to 6-2-17 Micom

Failure.

No

Are H/V sync input on IC401’s

Pins 1 and 2?

Yes

Check and replace IC401.

Yes

Check H/V sync input line.

No

Check and replace IC201.

No

WAVEFORMS

24

26

25

27

24

5.28 V (IC201, #31)

CH1 P-P = 5.28 V CH1 RMS = 1.218 V

25

4.96 V (IC201, #30)

CH1 P-P = 4.96 V CH1 RMS = 350 mV

26

5.48 V (IC401, #1)

CH1 P-P = 5.48 V CH1 RMS = 1.362 V

27

4.48 V (IC401, #2)

CH1 P-P = 4.48 V CH1 RMS = 284 mV

6 Troubleshooting

DP14L*/DP15L* 6-5

6-1-7 Poor Focus

Improved Focus?

Aging monitor and check focus

change for 1~2 hours.

Check Focus lead from FBT to

CRT Socket.

Adjust Focus VR.

No

Yes

Are the CRT Socket and

connection OK?

Replace and connect it.

Check and replace CRT.

Yes

Yes

No

6-1-8 Purity Failure

Degaussing

Is purity OK?

Done

No

Yes

IS degaussing circuit OK?

Refer to 6-2-20 Degaussing Failure.

Yes

No

Check if there is strong

electric or magnetic fields near

user’s circumstance?

Recommend free electric or

magnetic field.

No

Yes

Change CRT and readjust

misconvergence and color.

6 Troubleshooting

6-6 DP14L*/DP15L*

6-2 Detail Repair Section

Notes: 1. If a picture does not appear

check first • if AC power cord is plugged or not,

• if signal cable is connected or not,

• if signal generator (PC) is operated well or not (DPMS mode)

• if the Timing mode is out of spec or not (14”: 30~55 kHz, 15”: 30~61 kHz)

Does recitfied voltages of

secondary part appear on C620,

C622, C623, C624, C630?

Refer to 6-2-3 No Raster and

6-2-12 High Voltage Failure.

Check and replace D406, D407, D408,

IC101, Q402, Q410, Q504

Yes

Are D608 ~ D612 OK?

Replace it.

Check and Replace

IC601, T601.

Check and replace D602, D603, D607,

IC601, T602.

No

No

Does rectified voltage

(1.4 x AC input) of primary part

appear on C607?

Check and replace

D601~D607, FH601, TH602.

Yes

Yes

No

Is IC601’s Pin 1 OK?

No

Yes

Yes

Is IC601’s Pin 5 OK?

NoYes

Does rectified voltage

(1.4 x AC input) of primary

part appear on C617?

No

6-2-1 No Power

Check and replace IC601, T601.

Check and replace T601 and

around parts.

WAVEFORMS

1

2

1

410 V (IC601, #1)

CH1 P-P = 410 V CH1 RMS = 332.8 V

2

8.40 V (IC601, #5)

CH1 P-P = 8.40 V CH1 RMS = 4.680 V

Desolder IC601’s Pin 1.

No

6 Troubleshooting

DP14L*/DP15L* 6-7

Is LED blinking? (1 sec toggle)

Check and replace

OP201.

Make sure that there is No H/V sync

from signal generator. (Signal cable

should be connected)

Yes

Are there 0V on IC201’s Pin 5 (sus)

and 0V on IC201’s Pin 6 (off)?

Check and replace IC201.

Check and replace IC201.

No

Is OP201 OK?

Yes

No

No

Yes

+6.3 V line Off?

Check and replace Q603, Q604.

No

+12 V Off?

Check and replace Q605 ~ Q608.

No

Yes

Yes

Done

6-2-2 DPMS Failure

6-2-2 (a) Off Mode (No H/V sync)

6 Troubleshooting

6-8 DP14L*/DP15L*

6-2-2 (b) Suspend Mode (H sync: OK, V sync: No)

Is LED blinking? (0.5 sec toggle)

Check and replace

OP201.

Make sure that H sync is OK and V sync is

not. (Signal cable should be connected)

Yes

Are there 0V on IC201’s Pin 5 (sus)

and 5V on IC201’s Pin 6 (off)?

Check and replace IC201.

Check and replace IC201.

No

Is OP201 OK?

Yes

No

No

Yes

+12 V Off?

Check and replace Q605 ~ Q608.

No

Yes

Done

6-2-2 (c) Stand-by Mode (H sync: No, V sync: OK)

Is LED blinking? (0.5 sec toggle)

Check and replace

OP201.

Make sure that H sync is not and V sync is

OK. (Signal cable should be connected)

Yes

Are there 5V on IC201’s Pin 5 (sus)

and 0V on IC201’s Pin 6 (off)?

Check and replace IC201.

Check and replace IC201.

No

Is OP201 OK?

Yes

No

No

Yes

Is high voltage On?

Refer to 6-2-3 No Raster and

6-2-12 High Voltage Failure.

No

Yes

Video Mute?

Refer to 6-2-16 No Video and

6-2-13 I2C Failure.

No

Yes

Done