Samsung 42 Plasma Wont turn on PSPF411701A

[anotherdude]

Just got a 42 inch plasma that wont turn on, apparently repaired previously, that it would take x ammount of time to turn on etc, got told they soldered something other than that i don't know

anyway got the psu board out PSPF411701A and it appears someones done a bodge job on it previously from what i can see anyway

looked through various places about checking the f803 fuse and the 801-802 mosfets but not sure if it's even fixable at the minute with the previous symptomns

took some pictures anyway it looks like whoevers repaired it did poor soldering too

[tw2005]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Looks to me they're transistors which have literally blown apart.

Edit: Did a quick google and Copell TV have a kit, here's a quick quote.

http://www.ebay.com/itm/PSPF411701A-...-/110882821356

The signs of failure are usually visible with naked eye in the form of burned / blown open transistor QX801 and/or QX802 and usually burned pair of resistors RX833/RX802 and/or RX803/RX832 which are closely located to the transistors at the bottom of the board.

Whenever the resistors are blown it is almost guaranteed that the SMD diode they are connected in parallel with is also blown.

Kit contents:
•
Transistors QX801 and QX802

•
SMD resistors RX802, RX803, RX832, RX833 (all with the same value)

•
SMD resistors RX804 and RX805 (same value)

•
SMD diodes DX803 and DX804 (same kind)

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

ye done some reading on the fault apparently it's common to get clicking

but i don't get any clicking the led is lit up at the power button but get no response from the button or remote

read that replacing those isn't the only thing that needs replacing when clicking

F803,QX801 and QX802,RX802, RX803, RX832 and RX833,RX804 and RX805,DX803,DX804

can see repair kits on ebay as price those parts up on there own and there a £1 or 2 anyway

but didnt want to order in case i'm flogging a dead horse so to speak as it does not click

and as they've blown i don't know if it's bad soldering as you can see or theres another fault causing them to blow as the board was scorched and theres now a black mark on the chassis of the tv too, but i've seen caps blow due to bad soldering in the past could be the same?

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Looks to me they're transistors which have literally blown apart.

Edit: Did a quick google and Copell TV have a kit, here's a quick quote.

http://www.ebay.com/itm/PSPF411701A-...-/110882821356

The signs of failure are usually visible with naked eye in the form of burned / blown open transistor QX801 and/or QX802 and usually burned pair of resistors RX833/RX802 and/or RX803/RX832 which are closely located to the transistors at the bottom of the board.

Whenever the resistors are blown it is almost guaranteed that the SMD diode they are connected in parallel with is also blown.

Kit contents:
•
Transistors QX801 and QX802

•
SMD resistors RX802, RX803, RX832, RX833 (all with the same value)

•
SMD resistors RX804 and RX805 (same value)

•
SMD diodes DX803 and DX804 (same kind)

ye seen those kits same as this but this has the fuse too http://www.ebay.co.uk/itm/271099719223

just everywhere i'm reading it states clicking nothing about it not turning on but as there blown i'm guessing thats why

hate smd components too, just so fiddly

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

so replaced the parts and still the same, i'm lost now on what to do next

i get a blue led at the bottom like it's in standby, i press the power button on remote the light disappears and the tv makes no attempt to turn on

[tom66]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Did you replace the SMD diode too?

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Did you replace the SMD diode too?

i replaced everything in this kit http://www.ebay.co.uk/itm/271099719223

the one thing i found wierd though is the fuse is referred to as f802 but can't find any reference to that only f803

[tom66]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Hmm, ok, so unplug the Y-main and X-main and see if it stops clicking.

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Hmm, ok, so unplug the Y-main and X-main and see if it stops clicking.

no thats the point there is no click

[tom66]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

OK... Do you have a lit up power LED?

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

OK... Do you have a lit up power LED?

yes it's a blue led at the front, found if i press the button on the tv the led remains there but if i use the remote it disappears and if i continue to press power on the remote the led does come back

[tom66]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Unplug the power button and see if you can turn it on with the remote?

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

no response as far as i can tell as the blue led goes when i unplug it

[tom66]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Hmm, maybe the IR sensor is on it too. Can you remove it and check it is not stuck down?
I have had TVs with stuck power buttons stopping them from powering up.

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

could it be the controller/sub pcb's

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Hmm, maybe the IR sensor is on it too. Can you remove it and check it is not stuck down?
I have had TVs with stuck power buttons stopping them from powering up.

nope just tried buttons not stuck

just found this http://preher-tv.blogspot.co.uk/2010...-repaired.html

the 2nd part about the controller sub pcbs, could that be it?

[tw2005]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

I don't have any genius ideas for you but on that heatsink you replaced the FETs on I had the same generation PSU for a 50" which had cracked solder joints and would go dead with flexing.

maybe check out the remaining joints if you have not touched them up just in case it's something simple.

[anotherdude]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

not sure if i'm narrowing anything down here but plugged it in and didn't hit the power button and got my multimeter and started testing parts on the board

nothing gets over 1v including fets and the 5.3v test point



or am i way off here? and that voltages should only kick in when the set is turned on?

[Clydeuk]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

You can take the swap this swap that route until you hit the problem, or start down a logical process, which I think is where you are with the power supply at the moment. First check you should be getting some outputs and if 5.3 volts is all you're getting chances are that is your standby supply, which is always there and separate from the main supplies. What we need to find out is if the other supplies are being pulled down by a short-circuit (no clicking means less likely to be the normal failure that a lot of people have had), a bad previous repair is focussing attention there as well, not a bad place to start. Time to do some basic supply tests, isolate what you can, and jump the standby 5volts to the PS-ON (or whatever it's called in this) and see if any other supplies come up. Can you send a photo of the low voltage connector area on the PSU board (the ones that connect to your main board) hopefully with voltage markings on them, then we can tell you how to proceed.

[Clydeuk]

Re: Samsung 42 Plasma Wont turn on PSPF411701A

Those two FET's have had a crisis, to me they appear to be on the Hot side of the VA supply, I wouldn't be probing around there with a meter, in particular any voltage on those is in relation to the hot ground only. They wont fail for no reason either.