Samsung LN52C530F1FXZA No backlights

[SHADOW3277]

Picked this up from my local recycling center.

The TV turns on with no backlight. There is an image using a flashlight.

There are 2 450v caps on the PS that I get 393 volts at with the set turned on.

The power supply (BN44-00343B) voltages are as follows:

Connector CN802 (from Main)
Pin
1. B13v - 12.6 volts
3. B13v - 12.46 volts
5. B13v 12.46 volts
7. GND - 0 volts
9. GND - 0 volts
11. B5v - 5.1 volts
13. B5v - 5.1 volts
15. 13/18VS - 12.46
17. 13/18VS - 12.46

2. Lamp_Det - 0 volts
4. 5w_Inv - 5.1 volts
6. PWM_Dim - 2 volts
8. H_sync 1.7 volts
10. GND - 0 volts
12. GND - 0 volts
14. B5v - 5.1 volts
16. B5v - 5.1volts
18 Pow_On/Off - 0.88 volts

Connector CNI802 (to inverter)
1. 12v - 12.46 volts
2. FB - 0 volts
3. FB - 0 volts
4. GND - 0 volts
5. GND - 0 volts
6. LD - 9 volts
7. LD - 9 volts

Not sure the proper way to test the inverter.
Looking for some guidance in narrowing down the issue and repairing it. Thanks for your help.

[budm]

Re: Samsung LN52C530F1FXZA No backlights

Check the capacitance of that cap (gray cap with 474 printed on top) in the middle of the board next to the fuse, see if it has bulging sides and the capacitance is still OK, 0.47uF 450V.

[SHADOW3277]

Re: Samsung LN52C530F1FXZA No backlights

I'm unsoldering the cap to check capacitance. But looking at it at an angle it does look like one side is bulging. Did not see that before. Will report back in a few minutes after I get it unsoldered.

[budm]

Re: Samsung LN52C530F1FXZA No backlights

That is the common failure cap in the SAMSUNG power supply, the cap is 0.47uF 450V Polypropylene type for that backlights inverter circuit.

[SHADOW3277]

Re: Samsung LN52C530F1FXZA No backlights

I unsoldered the cap, and yep there is a bulge on the one side.

capacitance reads OL on the meter.

Would this be a good one to replace it with?

http://www.digikey.com/product-detai...174-ND/5881199

[budm]

Re: Samsung LN52C530F1FXZA No backlights

That will be fine, best to go up to higher Voltage rating like 650V and up.

[SHADOW3277]

Re: Samsung LN52C530F1FXZA No backlights

Thanks budm

[SHADOW3277]

Re: Samsung LN52C530F1FXZA No backlights

I can't seem to find one at 0.47 uf on Digikey that goes beyond 630volts

Here is the one I found:

http://www.digikey.com/product-detai...167-ND/5881192

[vinceroger69]

Re: Samsung LN52C530F1FXZA No backlights

That should do the job fine.

[budm]

Re: Samsung LN52C530F1FXZA No backlights

that should do the job fine.

+1

[SHADOW3277]

Re: Samsung LN52C530F1FXZA No backlights

Caps came in the mail this morning. Popped in the new cap and the TV has been playing perfectly for the last hour.

Thanks for the help budm and vinceroger69.

[budm]

Re: Samsung LN52C530F1FXZA No backlights

Thanks for the follow-up on the repairs.

[oohimedgy]

Re: Samsung LN52C530F1FXZA No backlights

Thanks for the follow-up on the repairs.

Budm, I have the same board but im getting 0v on my LD pins to the backlight inverter instead of the 9v OP has. I dont have any noticable damage after inspection on all the caps including the 474 cap. I wanted to narrow thigs down before i started resoldering all new caps, and was hoping you could point me in the right direction.

I was getting some weird voltages on the test pads on the backlight inverter around the 1.2v range instead of the typical 0.2. I checked the resistance on all the inverter transformers and they all read normal except for the single one that points north and south which is giving me no continuity and no resistance reading even at 2kOhm, so I know I need to replace that, but figured if I did, i might end up blowing it out again if I didnt get the LD 0V pins sorted

Connector CNI802 (to inverter)
1. 12v - 12.95 volts
2. FB - 0 volts
3. FB - 0 volts
4. GND - 0 volts
5. GND - 0 volts
6. LD - 0 volts
7. LD - 0 volts

[dopalgangr]

Re: Samsung LN52C530F1FXZA No backlights

Thanks Budm,

You saved my mom a new TV!! She had the same issue and replaced that cap and she's good as new. I appreciate your wisdom as well as the .47 fix

[poursergio]

Thanks budm! Worked for me too!