Samsung le32c530f1w not switching on

[Kairi]

Hi all,

I bought this TV from eBay with the intention of fixing it for myself. The seller claims that the TV takes a long time to switch on although I've yet to have it switched on!

Basically when you try to turn it on from standby, the red light blinks a couple of times and then turns off. The screen does not come on nor does the LCD back light. I took the back cover off and and immediately noticed a faint buzzing from the PSU board. After some detective work involving a plastic pen between the suspected components and my ear, I localised to buzzing to be from a Metallised Polyester Film Transistor (CP812). The capacitor only buzz when the TV tries to switch on but not in stand by.

According to the schematics, this capacitor is part of the Power Factor Correction circuitry on the DC side. I am unable to identify what the value of this capacitor and would like some help on choosing the correct replacement. All it's written is 2W 105K SIC 460S.

Is it unusual for the Polymer cap to fail? I heard these tend to be pretty reliable. I haven't tested the electrolytic capacitors but they all look fine to me and I don't particularly want to start de-soldering components unless I get more evidence that the failure is from the electrolytic caps.

Picture of the PSU board is attached and schematic is on page 93 http://loraart.ru/LE32C550J1W_Service_Manual.pdf


Edit: I removed the cap from the board and tested it. It's reading 958.2nF.

[budm]

Re: Samsung le32c530f1w not switching on

I do not see CP812 in the diagram, the one in your picture is 1uF 10% (105K, 105 = 1000nF, K= 10%) Tolerance around 450V rating, more likely to be CP801S as shown in the diagram.
Are you getting around 170VDC right at the TWO LEGS OF THE MAIN FILTER CAP when TV is OFF, and about 360~400VDC when TV is powered ON?
BTW, the sch in your link is for BN44-00338A, you have -00339B.

[Kairi]

Re: Samsung le32c530f1w not switching on

CP812 is on coordinates E4 on the schematics.

On stand by the voltage at the main filter cap is 326v and 383v when the TV is attempting power up.

In the meantime I have also tested the bank of capacitors on the far left of the board off-circuit and they are all within tolerance and ESR is 0.1% or less.

[Kairi]

Re: Samsung le32c530f1w not switching on

I'm trying to source a suitable replacement for that capacitor. I'm looking at a UK supplier RS Components and I'm not too sure if its a Polyester Film, Polypropylene Film or Polystyrene Film Capacitors.

Can I have the guidance from a more knowledgeable member?

http://uk.rs-online.com/web/c/passiv...ts/capacitors/

[Kairi]

Re: Samsung le32c530f1w not switching on

Sorry, I can't seem to edit my above post...

Will this one be suitable? I know the size is much larger but it won't be an issue as I can fit it elsewhere on the board.

http://www.maplin.co.uk/p/lcr-audio-...apacitor-kr78k

[tom66]

Re: Samsung le32c530f1w not switching on

Personally, I doubt that capacitor is bad.

Some checks:
- Do you have 24V output going to the inverters?
- Do you have 5.3V standby and/or 5.3V run voltages?
- Do you have 13V supply (for audio)?
- What voltage do you measure across CM803? (Primary side, small, probably near ICM801 on heatsink.)

[selldoor]

Re: Samsung le32c530f1w not switching on

I wondered that also - they dont fail that often.
Going back to the it took a long time to come on I know you say you have checked the caps (or some of them) and they look good but may be worth trying pre heating sections of the board with a hairdryer - sometimes reveals
failing caps or cold joints.

[budm]

Re: Samsung le32c530f1w not switching on

Here is the SCH from TOM that match your BN44-00339B. I do not think that cap is bad, the circuit will function without that cap, your PFC Voltage booster is working.

[Kairi]

Re: Samsung le32c530f1w not switching on

I have 25v going to the inverters
I have 5.1v
I have 12.1v going to the speakers
Voltage across CM803 is 25v

I found that the backlight comes on when I disconnect the cable the main board and the cap stopped buzzing.

[tom66]

Re: Samsung le32c530f1w not switching on

It seems more likely that you have a bad main board. Extremely common on c series Samsung

[Kairi]

Re: Samsung le32c530f1w not switching on

I found that I had an old electrolytic capacitor lying around in my components box with the correct values and went ahead with replacing it. You were all correct, the spare capacitor didn't help at all; the buzzing was eliminated but the TV still doesn't switch on.

Ok, how would I know for sure if the main board is indeed faulty?

[selldoor]

Re: Samsung le32c530f1w not switching on

Did you try heating main board gently with a hairdryer.
Post a good clear picture front and back and we might spot something.
Instead of unplugging the main board to get the lights on try keeping the main board connected but detach the lvds

[budm]

Re: Samsung le32c530f1w not switching on

"Ok, how would I know for sure if the main board is indeed faulty?" Because the backlights do come on when the cable between the Power supply and the main board is disconnected, the main board is keeping the bl_on (invr on/off) LOW.

[Kairi]

Re: Samsung le32c530f1w not switching on

I tried the heating both boards with a heatgun on low setting for about 30 second but still no sign on life. I have attached images of the main board as requested. I personally so not see any obvious signs of anything wrong with the main board.

I did some more observations and here's a summary of my findings...

When the TV is on standby, the capacitor does not buzz

When the TV is attempting to power up, the capacitor buzzes

With the main board disconnected but IVD board connected, the backlight comes on and the capacitor stops buzzing

The capacitor buzzes even when the inverter driver board is disconnected.

With both boards disconnected, upon plugging the power lead in, the capacitor still buzzes.

-- Edit --

I ran some more voltage tests at all the individual pins on both the connectors to the main board and inverter board and here's my findings of the voltages at any particular pin. I tested the voltage first with the main board disconnected and next with the main board connected. The inverter boards were connected at all times. Do these voltages mean anything?

[budm]

Re: Samsung le32c530f1w not switching on

PS ON should be minimum of 0.6VDC when main board is not connected, please recheck that again, the power supply is working

[Kairi]

Re: Samsung le32c530f1w not switching on

Yes, my bad. It is 0.7V. I probably misread my multimeter.

So based on the findings, we can conclude that the failure is not the PSU and that I should start investigating the main board? Is it feasible to track down and repair main board problems or will I be better off ordering a replacement board altogether?

I found this thread https://www.badcaps.net/forum/showthread.php?t=36322. It sounds interesting however I am able to switch the TV "on" from the touch panel. Any thoughts about this?

[Kairi]

Re: Samsung le32c530f1w not switching on

Just an update to say that I've replaced the AV board and the set is now working. Indeed the power supply wasn't the issue.

I'm still keen to find out what may have caused the AV board to fail as you claim that it is common for the Samsung C series.

[senndogg]

Re: Samsung le32c530f1w not switching on

I am trying myself to figure out. At the moment i have no C530 board to play with, but i extremely doubt that the memory gets corrupted.

[noledud]

Re: Samsung le32c530f1w not switching on

I have the same problem did we find a fix ?

[Hamie]

Re: Samsung le32c530f1w not switching on

just thought id update this, the problem is the EEPROM ic402 on the mainboard.
they need to be preprogrammed, Ohmsupplies sell them.