Samsung HP-T5054X/XAA

[Chas617]

Hello,

I was given this TV. No picture, no sound. Power supply relay clicks when plugging in power. Front blue LED will flash 5 times. Then relay clicks again. This cycle continues repeating until power is removed. I removed the back and visually inspected all boards. The power supply board (SMPS) had three leaking/bulging caps. Rather than try a repair I ordered and received a replacement from ShopJimmy. Replacing the SMPS did not fix the problem, still had the same symptoms.

The service manual troubleshooting steps had me disconnecting the cable from the X-MAIN, Y-MAIN and Buffer boards at the power supply. Each step isolated each board. The symptoms were still present. The manual now says to replace the power supply.

I measured each power supply voltage I could find and all test normal. The supposedly bad power supply, the one with the bad caps, tested normal as well.

What now? Any suggestions for what to check or test next? Replace the power supply yet again?

Any and all help will be appreciated.


Chuck

[nogger]

Re: Samsung HP-T5054X/XAA

Unplug ALL connections to the PSU board except for the mains input cable & the long cable that connects the PSU to the Main board (cable usually has a bright blue stripe running down one side) . Switch on power & PSU should click once & power up (All Va voltages 63v, 5.3v 12v 18v etc should be there but dont worry about Vs). If it still clicks the PSU IS faulty, try both PSU's that way. If it doesn't click click click then put each connection back one at a time until it starts to click.

Graham

[Chas617]

Re: Samsung HP-T5054X/XAA

Hi nogger and thanks for the reply!

While searching for solutions today I found a blog http://blog.coppelltvrepair.com/2014_02_01_archive.html that detailed how to troubleshoot the power supply. It had me jumpering some pins on a connector to turn on the power supply as well as triggering the higher voltage. When I did this all voltages checked out and the power supply relays only clicked once then it was silence. So, I now know that the power supply is good.

The power supply will only power up with either those pins jumpered or the cable from the main logic board connected. Once I connect the main logic board the clicking starts. This tells me that the main logic board is causing the problem. Does this sound like I'm on the right path?

Question: If I were to activate the power supply by jumpering the pins, can I then start reconnecting other boards without causing other problems?


Thanks again,

Chuck

[nogger]

Re: Samsung HP-T5054X/XAA

I'm aware of that method, that's how i normally test PSU's on the bench. I was going to suggest that way yesterday but thought it would be easier for you testing in the TV itself.

With just the power in AND the double row cable from CN801 down to the MAIN BOARD (not logic board) & everything else disconnected from the PSU switch on & you should be able to fire up the TV (of course no video etc) but the relay should pull in once. If it does, reconnect the X & Y board cables testing after each cable is inserted for clicking. If it clicks then that board is faulty. I suspect you have a shorted X or Y board & the PSU is shutting down for protection,

Graham

[Chas617]

Re: Samsung HP-T5054X/XAA

Graham,

This confuses me more than a little bit. If the power supply is triggered on by causing pin 4 of CN807 to go low how would only having CN801 connected ever turn on the power supply?? However, never being the one to ignore advice and guidance when asked, I did as you said; nothing connected to the power supply except the power in and CN801. And as I suspected, nothing at all happened. No relay click and no voltages at all.

I am at a loss here and really want to understand. So, if you have any other help to offer, I'm all ears!!

P.S. One thing I forgot to mention: The only thing that seems to work so far is the LED light center/bottom.


Chuck

[mmartell]

Re: Samsung HP-T5054X/XAA

Unplug the main board lvds cable from main-control board and put a jumper on the control board (pin5-6) and plug it in. This is just to take the main board out of the equation. On a working set this will give you test patterns. Still sounds like you received a bad supply though. Any lights on the control board ?

[tw2005]

Re: Samsung HP-T5054X/XAA

check out the ymain fets 88n30w see if shorted. common problem also with these is shorted upper buffer and shorted ymain especially yif you've managed to get the psu on and normal voltage outputs.

[Chas617]

Re: Samsung HP-T5054X/XAA

I really hate when it OPs fail to come back to report results, either bad or good. So, here I am one last time to report that I now have a working TV. I figured that since the power supply went into protect with the main logic board connected I went ahead and order a new one and replaced it. After hooking everything back up, the TV powered up normally with a nice picture. I was initially concerned as I thought I would have to adjust the voltages but everything measured good. I'll double check the firmware version and update it if necessary.

Thanks to all who chipped in with suggestions/help.


Chuck

[tw2005]

Re: Samsung HP-T5054X/XAA

If nothing has shorted on that PSU like the FETs in the heatsinks middle of the board, quite often these get fractured solder joints and that can cause shutdowns and clicking. reflow can fix but also often those fets blow once they unsolder.