Samsung ps50a457

[sordids999]

Ok so ive got this tv which was totally dead so i checked on the net for any symptons so found this site and basically removed all the parts they listed and tested,but i could not find nothing wrong so i put the power unit back on noticed a standby light was on and the tv works now.
so could it have been a cold joints etc ?

thanks

[tom66]

Re: Samsung ps50a457

Check all connectors seated and burn the unit in for a few days maybe on control board test patterns (auto gen using the jumper on pins 3-4.)

[sordids999]

Re: Samsung ps50a457

typical ran all last night and this afternoon but just went into standby

[tom66]

Re: Samsung ps50a457

Well if they were all that easy.....
Start by taking pictures of the boards. Sounds a lot like a main board fault.

[sordids999]

Re: Samsung ps50a457

so when i first had the tv it had no power it was totally dead

[tom66]

Re: Samsung ps50a457

So, what's the fault -now-? Do you have any 5V standby from PSU?

[sordids999]

Re: Samsung ps50a457

hi tom all i basically done was tested the following parts listed below due to the tv was totally dead (but did not test the mosfet )
F801S
BP802S
DP081
CP085
CP086
FM801S
FB801S
DQ801
DQ802
DB801
DB802
DB803

http://www.ohmsupplies.co.uk/Repair-...50A456-P50A457

tv came back to life after doing this ran for a few hours last night but today went into standby ill be home later to test the 5v standby

[sordids999]

Re: Samsung ps50a457

5v standby is 5.07 volts

[tom66]

Re: Samsung ps50a457

Any standby indicator? Unplug set and plug it in again - any flashes from light?

[sordids999]

Re: Samsung ps50a457

No tom

[tw2005]

Re: Samsung ps50a457

Sounds like it could be dry joints. In the picture I thought Q801 looked a bit sus but it is blurred. PSU looks similar to the 50Q91,96 which I had one with similar issue. Cracked joints on the FETs.

I'm assuming you have 5v standby the whole time.

[sordids999]

Re: Samsung ps50a457

Yes 5v standby constant I have since resoldered the MOSFET joints all working again at the moment

[tw2005]

Re: Samsung ps50a457

Yes 5v standby constant I have since resoldered the MOSFET joints all working again at the moment

When I discovered this issue I found when I flexed the board mid point I could get the TV to fault and just shutdown. hopefully this is all it was, no doubt we'll find out in time.

[sordids999]

Re: Samsung ps50a457

Still working today so keeping my fingers crossed

[tw2005]

Re: Samsung ps50a457

Did you see any obvious bad joints? intermittent faults are always fun, hope the luck continues.

[sordids999]

Re: Samsung ps50a457

Not really resoldered Q801 and Q802 still waiting for it to go into standby though

[tw2005]

Re: Samsung ps50a457

Can be hard to tell, but everytime you touched the board it came back mysteriously. I would have gone feral and touched up all the heatsinked parts to totally take that out of the equation but where those are that is the equivalent heatsink and FETs that gave me grief.

Nil cost and a bit of time, better than replacing boards straight away. I guess once it starts running longer than it has previously then our confidence will grow.

That one I had could run for hours, be good for a few days then just randomly drop dead but was perfect when it was going. Took me a week to get it to fault, that's when I thought I'd try and induce it with tapping the heatsinks.

Once I flexed the board that permanently made it worse, it was fun. Was a fix for a mate.

he just put up with it . i have seen one go up in smoke though with those bad joints.

[flocko]

Re: Samsung ps50a457

when it fails do you have the relays clicking when you power on? i have had two with relays with dry joints on the back of the board

[sordids999]

Re: Samsung ps50a457

I have a loud relay clicking when I turn it on anyway then it chimes and turns on

[Maroboy]

Re: Samsung ps50a457

Im new to the site hi