Samsung HP-T5054 BN44-00161A Issue

[culcuhain]

Got this Plasma and there is no stand by light and PSU just clicks over and over and over.

CN807 on PSU Board
Pin Label V-Standby V-PS-ON Jumpered
StBy 5.02V 5.03V
VS On .9MV .3MV
NC -- --
PS ON 4.15V Can check when jumpered, will try again later.
RTN -- --
5.3V 1.59V 1.6V
RTN -- --
RTN -- --
5.3V 1.59V 1.6V
5.3V 1.59V 1.6V

I have 138.6V across the two large main caps. I didn't check the Va or Vs since I don't have the 5.3V line. I am in the middle of installing the Shop Jimmy PSU Repair kit for the Va VS lines. Down to just replacing the surface mount resistors. Should have that done later today. I have both the TV and the PSU Schematics.

Any pointers on next steps or certain things to check? Thanks in Advance!

[dskall]

Re: Samsung HP-T5054 BN44-00161A Issue

Voltage across main caps looks low

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Agree, it doesn't look like the PFC circuit is working (still learning that part) and with no 5.3V I will not get the Va or Vs.... will know more late this afternoon....

[dskall]

Re: Samsung HP-T5054 BN44-00161A Issue

That is low for standby, should be around 165v. Boosted voltage should be around 390v

[budm]

Re: Samsung HP-T5054 BN44-00161A Issue

138.6VDC on the main filter cap, are you sure?
What did you use for the GND for the meter?
BTW, did you hear the two power relays click on when PS-ON is Grounded to force on the power supply?

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Main Filter Cap. Black Probe to (-) cap. Red Probe to (+) Cap. There are two caps.
When the PS-ON is jumpered to the RTN I get one click (turning on) then a second click, thinking it is protection. All boards are disconnected from the SMPS board.

[budm]

Re: Samsung HP-T5054 BN44-00161A Issue

Regardless if the PFC is not working, the minimum DCV on those two main filter caps (they are connected in parallel) should be around 165VDC, so I would verify that you do have 120VAC between the two inner legs of the bridge rectifier or not.

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

There are 2 bridge recifiers. 0.521VAC on one and 0.532VAC on the other....

[budm]

Re: Samsung HP-T5054 BN44-00161A Issue

No way you can have 138VDC on the two legs of the main filter caps CP802/803 with only 0.521VAC feeding the bridge rectifiers (they are connected in parallel).
To have 120VAC on the two inner pins of the bridge, at least the relay RL802S has to come on when PS-On pin is Grounded.
So find out for sure if the relays do come on or not (the two relays do not come on at the same time) and verify your measurement again when the result has no logical sense.

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

My bad. In standby it is the low VAC. Jumping the PSOn to RTN and the relay clicks. Inner pins spike to 12x.xVAC then a second relay clicks and I am at the 0.521VAC. So it looks like something it puting it into protection. Will look for that segment on the schematics

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Ok. Had some time to get back to this.
RX833 was the only bad SMD resistor. It read open (OL). All others were in spec.
At a loss on my next steps.

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

ok. Checked the stuff I replaced from Shop Jimmy Kit.
DS801 and DS802 Shorted
DX803 Shorted. DX804 not shorted
QX801 Shorted. QX802 Good.
QS801 and QS802 Shorted.
So it looks like I have an obvious issue that is causing all these to blow again.

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Ordered new SMPS Board (will still work on this one) and put her in. Reseated a few cables and adjusted some of the voltages (red pixels) and now she is good to go. My shop now has a TV...
Will start a new Repair thread on the SMSP board later to document the repair.

I appreciate everyone's help and the search function here. 2 more tvs to fix for friends.

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Update: Installed brand new OEM Power board. Set Va and Vs per panel. TV ran flawless for 2 hours. Then it shut down and again started the endless clicking.
Checked the Voltages. Have Standby and Power On. Wire the power on to the RTN pin and I get the endless clicking loop, same as before. Could a bad X or Y board cause the Power board to fail? Will be exchanging power board since it is under warranty for 1 year. Grrr....

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Any ideas if a bad X or Y board (or another board) can take out the power board?

[aaronwt6]

Re: Samsung HP-T5054 BN44-00161A Issue

Was the replacement board labeled 50" on the white sticker? There is a version of this board for the 42" as well (HP-T42xx). I'd be shocked if it even supplied enough current to turn on the 50" screen but that could explain the rapid failure.

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

It was for the 50" as ordered and as on the board. This a new power supply. I will be exchanging this one but I am curious as to if another fault a another board could take out the power supply. Thanks!

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Everyone agree then that the other boards would not take out the power board?

[culcuhain]

Re: Samsung HP-T5054 BN44-00161A Issue

Ok. "New" Board was actually factory refurbished and was definitely for the 50" RMA initiated. Should have the new main in 2 weeks or so. Will update everyone then. Will definitely triple check the X and Y boards.