Samsung PN50B550

[johns1mj]

I am a little stumped. I normally don't get this far in testing before I find a problem. I have a plasma with the click on and off no chime problem. I disconnected the y and x boards with no change. If I disconnect the logic board the tv will start up and play the samsung chime. I tried the 3-4 pin jump with no change. Most voltages check good.

The a/c det never changes.
The vs test point only gets to 34 then the tv shuts back off.
The va only gets to 25.
The vsc gets to -107
The ve gets to 10.85

I think I have a power supply issue. Can anyone confirm or advise further testing? Check the last picture. It is the only component I can find that physically looks wrong.

[ReeceyBurger123]

Re: Samsung PN50B550

Test the Ysus and Xsus fets for short circuits or remove the connectors and see if psu stays on. Basic steps here come on. Let us know cheers.

[johns1mj]

Re: Samsung PN50B550

I already stated in the first post I did remove the connectors with no change.

[johns1mj]

Re: Samsung PN50B550

The ac det always reads 0 to clarify.

[ReeceyBurger123]

Re: Samsung PN50B550

Ahh I see, not got much time for bcn atm so skim reading. Also what does Pson do when it clicks ?

[johns1mj]

Re: Samsung PN50B550

ps on 3.28 to 0 at the power to input connector.
ps on 3.95 to 0 at the logic connector
vs on goes from 0 to 3.23 at the logic connector.

[johns1mj]

Re: Samsung PN50B550

I understand its the holidays and people have other things to do. Thank you for replying.

[martino]

Re: Samsung PN50B550

sounds like a dead logic board to me.
Did you try forcing on the power supply by itself?

[johns1mj]

Re: Samsung PN50B550

Please explain forcing the power supply. I have never had a bad power supply that wasn't dead. Usually its the y or x boards I am rebuilding. If you want me to jump pin 3 and 4 on the logic then yes I did that. I do have another logic board, installed with same results, but it is untested.

[martino]

Re: Samsung PN50B550

Disconnect everything from psu.
connect ps-on via a approx 560ohm resistor to ground.
connect vs-on via a approx 560ohm resistor to 5v standby.
Measure the voltages.Repeat with y sus and x main connected.
Let psu discharge before plugging in x and y.

[johns1mj]

Re: Samsung PN50B550

Just to clarify, I turn the tv on. It clicks loudly. There are several smaller clicks in a row and then another loud click. This happens unless I disconnect the logic board. If the logic is disconnected the Tv will play the start up chine but no picture.
I tried the forcing it on as Martino suggested. It clicks on and then rapidly clicks. This happens if the y and x boards are connected or not. Both test the input and tcon were disconnected.

[martino]

Re: Samsung PN50B550

That's because it's the logic board that turns on the vs and va.
So with everything disconnected and ps-on and vs-on jumpered the psu still acts weird. Did you try to measure vs and va in this test?
This seems to narrow it down to psu,I would start by measuring all components on heat sinks for shorts. QP802, 803, QS801, 802,DB804, 814, DP802 especially.

[johns1mj]

Re: Samsung PN50B550

I did the shop jimmy repair kit on it. Didn't change it. I think it might be a bad transformer.

[chrismurphy]

Re: Samsung PN50B550

replace the rectangle blue cap on the power supply board

[johns1mj]

Re: Samsung PN50B550

There is 3 of them. I did replace the one next to the transformer. No change. I bought another power supply and plugged it in.

There was a flash of light and the magic smoke left my y-sus board.

I think there was more wrong with the tv then just the power supply.