Samsung PN42C450B1 Power Supply issues

[geneg]

Guys, wonder if anyone has run into this issue and has a solution. I have a Samsung PN42C450 plasma which had a couple issues causing it to fail. I determined the X sustsin was bad and also the buffer board had a shorted chip. I replaced these with tested used parts and also checked the y sustain which was still good. During the testing phase I saw that the VS and VA on the power board registered 290 and 79 roughly then shut down due to the bad x sustain. I pulled another PS from a another unit I had with a bad panel. Sill the same thing. I turned both down but the lowest they would go was 270 for VS and 61 for VA. I ordered another board off EBAY and guess what, the same. With all the new boards installed the TV turns on fine but still cannot turn the voltage down to match the screen voltage which is like 207 for VS and I think 50 for VA. All three power boards turn the TV on fine but all have the exact voltage issues where VS and VA cannot be turned down to the screen specs. Before I tear into the board and possibly order another board, has anyone else run accross this in this line of TVs which include the PL, PN, and PS series?

[freakaftr8]

Re: Samsung PN42C450B1 Power Supply issues

okay are you actually getting a picture like this when your VA is high you can easily damage the panel be real careful with this. Try adjusting voltages with the y sustain and z disconnected from circuit.

[tom66]

Re: Samsung PN42C450B1 Power Supply issues

Check your multimeter battery is not dead. In fact best to replace it outright.

[geneg]

Re: Samsung PN42C450B1 Power Supply issues

Thanks. Yes, I did not run the TV but a min or two knowing that the high voltage could damage it. Still stumped on what the issue is. I know my batteries are low on my fluke and will change tonight an also check some of the power board componets.

[geneg]

Re: Samsung PN42C450B1 Power Supply issues

tom66, thanks for your help, turns out the low battery in my Fluke was causing false readings. Really feel stupid but thanks. I should know by now to always check your equipment and never assume.

[retiredcaps]

Re: Samsung PN42C450B1 Power Supply issues

tom66, thanks for your help, turns out the low battery in my Fluke was causing false readings.

The newest generation of Fluke multimeters will actually display bAtt on the display and not display a reading until you change out the battery.

I bought a "non working" Fluke 175 (firmware 1.x) and while it does display the low battery icon, it still gives readings, albeit erroneous (typically high). The Fluke 170 series with firmware 2.x displays bAtt.

PS. I use all my "dead" 9V batteries in the older generation 70 series which gets 2,000 (two thousand) hours of battery from a new 9V battery. It only draws about 250 uA in operation.