Samsung PS43F4500 - Identify Component

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Thanks flocko, I'll make those checks and be back with the results.

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

No shorts across any of the mosfets or diodes and the capacitors all have fairly high resistance (K ohms) to ground.

[Alastair E]

Re: Samsung PS43F4500 - Identify Component

'red-black-yellow-gold' cant be right...

That resistor in the picture--looks like a 270K which is red violet yellow, gold = 5% tol...
--on these things these resistors generally used as leak-down across caps in the various supplies--such as any derived or floating-supplies such as VSCAN etc...

--It being o/c therefore wouldn't cause any visible problem with set operation--Till you grabbed the board just after it had been run!

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Hello Alastair, I replaced the board because the arcing had burnt through part of the pcb and solder pads.
Unfortunately it looks as though that can't have been the only problem having Va & Vs still dropping and Out-A which is connected to the panels X ribbons also being too low in voltage.

[ReeceyBurger123]

Re: Samsung PS43F4500 - Identify Component

These use chained Erc so Ymain could of damaged Xmain Db have you checked that for S/C ?

[flocko]

Re: Samsung PS43F4500 - Identify Component

your test shows no problem with the power/X main board the fact that you see Vs+Va a working remote and sound tells me that. did you check the buffer ICs on the new board for shorts, as most of these boards are pulled from damaged screen set they need checking ,and most will be found to have one or more shorted buffer ICs. it is also worth saying that these PDP were so thin that they crack without any outside help, my bet is bad your new Ysus is faulty

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Hello Flocko,
I did do a quick test on the buffer board connectors prior to installing it but maybe too quickly so I'll repeat the test more carefully this time.
I'm not very mobile at the moment due to recovering from an injury so everything is taking me time to do. I agree with you that a second check wouldn't hurt. Thanks once again for your input.

The one thing that sticks in my mind is that although Va, Vs drop from their nominal voltage, OUT-A voltage which connect to the X-tabs never rises past the 12V to what I believe should be 79V in normal operation. This figure as said earlier was found on the only other posting of a fault on this set where thankfully all the operating voltages were given.
Thanks

[flocko]

Re: Samsung PS43F4500 - Identify Component

Yes do a low ohm test on the buffers (floating ground- ribbon connections ) Have you tried to see if voltage comes up with Y sus unplugged (not sure what it should be) Hope your back to full strength soon Flocko

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Hello Flocko,
Thanks for your concern. Trapped the nerve in my back lifting a TV last week. It wasn't even heavy but I twisted at the same time even though I should know better.

I've already tried with the supply cable removed from the Y board but the VA, VS, etc supplies read the same.

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Looks like my initial checking of the buffer IC's was not as precise as it should have been. On double checking as suggested, buffer IC U5033 has a couple of lines shorted to both Out_L and Out_H.

I have now requested a return via ebay.

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

'red-black-yellow-gold' cant be right...

That resistor in the picture--looks like a 270K which is red violet yellow, gold = 5% tol...
--on these things these resistors generally used as leak-down across caps in the various supplies--such as any derived or floating-supplies such as VSCAN etc...

--It being o/c therefore wouldn't cause any visible problem with set operation--Till you grabbed the board just after it had been run!

Hello Alastair,
Looking at the resistor on the replacement board it is 200K (Red, Black, Yellow, Gold) and is across the 47uF, 250V capacitor providing -Vscan

[flocko]

Re: Samsung PS43F4500 - Identify Component

I would be checking the buffers on the old board with the burnt resistor,to make sure they are not shorted, if the buffers are damaged in the same way(place) it could show you have a defective PDP(shorted). and that could have damaged the replacement board,if you say you checked it before fitting and you dont think it was shorted then.

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

I would be checking the buffers on the old board with the burnt resistor,to make sure they are not shorted, if the buffers are damaged in the same way(place) it could show you have a defective PDP(shorted). and that could have damaged the replacement board,if you say you checked it before fitting and you dont think it was shorted then.

Thanks Flocko,
That was the first thing I did when I found the fault on the replacement board. Did a comparison with the old board and did not find any buffer problems on that board.

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Replacement board arrived, slow delivery however checked out OK. Soldered the resistors so that the same problem should not occur with this board and all up and running.

[flocko]

Re: Samsung PS43F4500 - Identify Component

Glad its all fixed.How is the back? better I hope. It always pays to fully test all S/H boards as most will come from sets with damaged screens.

[dick_barton]

Re: Samsung PS43F4500 - Identify Component

Have literally just got back on my feet this week without using a walking stick. My back is still not 100% so I'm being extremely careful. Just cannot believe how long it's taken to get to this point. Anyway I'm getting there and that's what matters. Not lifting TV's at the moment.

Thanks for asking.

[stefan67]

Re: Samsung PS43F4500 - Identify Component

Guys, can you help me? I have some problem with my PS43F4500, screen is black/blank, have a sound. I checked the Va and Vs with connected all ribbon cable to Y-SUS board and Mainboard, Va and Vs drop until zero. With no ribbon cable connected to Y-SUS board, still the same.

Checked all board, seems no burnt component. But I check the transistor near the Va and Vs point, two transistor in the middle dead. Is this the cause of no display on my Plasma TV? Or there is another problem caused by the dead transistor?

[stefan67]

Re: Samsung PS43F4500 - Identify Component

Guys, can you help me? I have some problem with my PS43F4500, screen is black/blank, have a sound. I checked the Va and Vs with connected all ribbon cable to Y-SUS board and Mainboard, Va and Vs drop until zero. With no ribbon cable connected to Y-SUS board, still the same.

Checked all board, seems no burnt component. But I check the transistor near the Va and Vs point, two transistor in the middle dead. Is this the cause of no display on my Plasma TV? Or there is another problem caused by the dead transistor?

[UPDATE] VS ON going to 0 Volt from 3,3 Volt after a second (checked on pin no 6)