Samsung plasma PS50B430P2W relay clicking noise - no picture

[Damtom]

Hi All.

I need advise to indetify which component is faulty.


Samsung plasma PS50B430P2W (serial number on picture below) keeps clicking on and off (relay noise ) and no picture on the screen. I tried to disconnected all components from power board and results are that when I disconnected Y main board TV started , well at least there was samsung intro sound coming from speakers. Y main board is connected directly with power board and X main board is connected to Y main board. I checked voltages and :

If Y main is disconnected from power board I get :

Va starting at 130Vac going down to 0V
Vs Starting at 409Vac going down to 0V

If Y main is connected to power supply I get :

Va starting at 23Vac going to 17Vac(relay clicks off) and back to 23Vac(relay clicks on)
Vs 0V all the time
Vsc 0V
Ve 0V

I attached picture of white sticker with proper voltages.
What have I done so far ? - I have changed most of electrolytic capacitors on power board.

Power board number BN44-00274B

Can you help me at least identify which board needs replacing or maybe help fixing existing fault . Kind regards

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

So does it start if the x is unplugged?

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

So does it start if the x is unplugged?

it won't start either

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

So you have a problem with your y-sus.
Also Put your meter in DC not AC

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

so why there is no Vs on power board when y board plugged?

I am thinking between power board or Y board

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

The vs drops because there is a problem with the ysus or buffers.

Try unplugging the buffers and try again.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

what do you mean by buffers?

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

Long green board that plugs into the y-sustain.

Remove it and see if your voltages come up.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

I just catch what you mean by buffers. I disconnected them. Va 10v till 0V and back, Vs 1.66V till 0V and back, Vsc from Y main still 0V. all voltages DC

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

OK so you have a faulty y-sustain.
You'll either need to replace it or repair it.

You'll also need to make sure it's not damaged the x and buffer.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

any hint what to check on Y board, board number is LJ41-07016A.

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

First put your meter in ohm setting and see if the vs input is shorted to ground. If so check all igbts and diodes attached to the heatsinks for shorts.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

meter set to 2000ohms show 247 between Vs and ground

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

OK so you have a short. Check the heatsinks and see if any of the igbts have low ohms in all directions (or put your meter in diode mode or buzzer mode) anything that beeps in all directions is probably shorted or in circuit with something that is)

No need to desolder at this point as the short should be pretty obvious.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

thanks for help, I found transistors shorted attached to heatsink, tomorrow after my day work, I will write exactly symbols, and I will need further help. thanks Hamie for you time.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

Hi again .

I attached picture with numbers in red showing which transistor is shorted.

1. Q5304
2. q5303
3. diode d5402 with meter set to 2000 ohms gives reading 448 one way , other way shows 278, as far as i remember the current should only go one way

4. Q5403
5. Q5101
6. diode d5101 resistance one 039 other way 027
7. diode d5406 resistance 417 other way meter shows 1 sometimes 327 then back to 1
8.Q5402
9. Q5501 seems to be ok this transistor.

can you give me further advise , thank you

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

If 1-2-4-5 are all short then you can't test the diodes properly.

I'm surprised 7-8 are short.

I'd suggest is removing 1-2-4-5 and rechecking diodes once they are out of circuit.

For diodes you're better checking them in diode mode.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

thanks just to be clear I need to remove heatsink radiator first? I don't know how to describe but legs of radiator are in some kind of socket in board

[Hamie]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

No the legs are riveted. It's no big deal.

Unscrew the igbts from the heatsink and bend them forward. If they are screwed the heatsink will take the heat away from your iron.

Get the leg free that's not riveted then simply walk them out the board. Use some flux and wick to clear the pads once removed.

[Damtom]

Re: Samsung plasma PS50B430P2W relay clicking noise - no picture

Hi again

you were right. 1, 2 4 5 and 8 transistors shorted. diode 3 and 6 are ok once transistors are out. diode 7 with meter set to diode shows me one way 435 other way 1035, I'm not sure if this diode is OK.

also to remove some transistors I had to take out 4 big green capacitors, I checked them and they are OK.

can you help with further advise, thank you Hamie