ps42b430 doesn't turn on

[anna1980]

I have a ps42b430 which doesn't turn on
powerboard is a bn44-00273b

The only voltage I get on the mainboard is a nice 5.3 volt on standby.
That gives me a very nice red light on the from but thats it

I got the schematic from tanya but those are only 90% accurate

Are there any options I can try

Disconnecting x and y-sus doesn't seem relevant at this moment but I've tried

[Andrew F. Ali]

Re: ps42b430 doesn't turn on

Most likely the PSU is OK, but if you post clear focused pics of the PSU connector that go to the Main Bd. I could help you to self-test it. What make of TV is this?

[ajshoe]

Re: ps42b430 doesn't turn on

samsung 42" plasma

[R_J]

Re: ps42b430 doesn't turn on

Do you get PS_ON voltage to the power supply when the power button is pressed? or here any relay click?
I would also check the solder connections on the power supply components mounted to the heatsinks, and check the solder connections on the transformers also.

[Andrew F. Ali]

Re: ps42b430 doesn't turn on

With Samsung the VS-ON would have the 5Vstdby and the PS-ON would go to GND for the PSU to start up. Post a photo of the connector to the Main Bd. Yes build a Test lamp for the Vs connector as a load using two 120Vac household bulbs in series.

[anna1980]

Re: ps42b430 doesn't turn on

I just did some tests. And i think its the mainboard but im not sure

I noticed that when i heated the powersupply it came on. It showed the menu of the tv.
After a couple of seconds it would turn off but alll voltage would be there Vs Va en alle the 5v. My first reaction. Bad caps. So i replaced all but the three largest.

Same problem. I saw that if you connect ps_on with ground and bridge the header pins 3 and 4 on the header on the logic board it goes in test modus. When powering up it switches between colours.

Futhermore when it did powerup with main board attached it would show the picture on the attached bluray player. Am I on the right track by assuming a faulty mainboard

[Andrew F. Ali]

Re: ps42b430 doesn't turn on

I just did some tests. And i think its the mainboard but im not sure

Same problem. I saw that if you connect ps_on with ground and bridge the header pins 3 and 4 on the header on the logic board it goes in test modus. When powering up it switches between colours.

You did the Logic Bd test with the Main Bd. disconnected? Yes? Then I would say yes, go for a new Main Bd.

[anna1980]

Re: ps42b430 doesn't turn on

You did the Logic Bd test with the Main Bd. disconnected? Yes? Then I would say yes, go for a new Main Bd.

When heating the top left quadrant of the mainboard, the machine turns on and displays a picture. So its the mainboard. I could try a reflow of the board but that's only a temp fix.

Thanks for all the help

[Andrew F. Ali]

Re: ps42b430 doesn't turn on

If you can get a replacement Main Bd. go for it. As a temporary measure, if you are doing the reflow do it with a Hot air Station at 275-300C and NOT baking in an oven