Samsung PS51E450 Plasma Problem.

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

Hi Tom sorry its late but got that video onto youtube to show you (tv is upside down in video) https://www.youtube.com/watch?v=irWu...ature=youtu.be

[tom66]

Re: Samsung PS51E450 Plasma Problem.

Yeah that's quite a visible flash so I have to say "I don't believe you" when Vs only measures 0.07V. If your meter is autoranging, try setting it to manual 600 or 1000V DC.

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

Ok Tom will try that tomorrow afternoon and post results. Its a new multimeter. Unsure if its auto ranging.

[tom66]

Re: Samsung PS51E450 Plasma Problem.

Does it have about 30 positions on the switch or just a few?

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

Does it have about 30 positions on the switch or just a few?

24 positions on it Tom.

[tom66]

Re: Samsung PS51E450 Plasma Problem.

Probably not autoranging then...

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

Tom is it VS from power board you want me to measure ?

[tom66]

Re: Samsung PS51E450 Plasma Problem.

Yes.

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

ok i am going to measure ALL voltages from power board and post results.

[tw2005]

Re: Samsung PS51E450 Plasma Problem.

Not sure if this has been noticed but there is no Xmain, just x-buffer, both x & y main combined, X/Y-main

[tom66]

Re: Samsung PS51E450 Plasma Problem.

I'm not certain about that, would need to see underneath X-main, the green caps on it suggest some power electronics (if only SUS - the ERC being on Y-main...)

I did see an old LG 42T1 panel with combined Y/Z-sus; the Z-extension board only had a few protection diodes and poly caps. I also have had 42PQ3000 & 42PG3000 LG plasmas (42G1A/42G2) which also had partially combined Y/Z-sus.

[tw2005]

Re: Samsung PS51E450 Plasma Problem.

I'm not certain about that, would need to see underneath X-main, the green caps on it suggest some power electronics (if only SUS - the ERC being on Y-main...)

I did see an old LG 42T1 panel with combined Y/Z-sus; the Z-extension board only had a few protection diodes and poly caps. I also have had 42PQ3000 & 42PG3000 LG plasmas (42G1A/42G2) which also had partially combined Y/Z-sus.

[tw2005]

Re: Samsung PS51E450 Plasma Problem.

Maybe they're using the term loosely. there 's a bit more to it but that's the name they gave it.

[tom66]

Re: Samsung PS51E450 Plasma Problem.

Yes, there are SUS_UP+SUS_DN IGBTs on there.

Everything else, including Ve(common bias voltage) and energy recovery/resonance is done on the XY-main.

Interestingly: there appears to now be an FPC DET built into a Samsung X-buffer, look at the connections coming off the FPCs. I bet if it detects a broken X-main FPC it'll shut down. That would be a dead panel (though it would probably not be too hard to fix.)

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

ok tom switched tv on and left on for a few minutes then tested voltages.

voltage from PSU to X-Buffer:

VS 10.06v
VS 10.06V
NC 0V
VA 1.6V
GND
D15V 14.77V
D5.3V 5.25V
GND
VSON 0V
VS_CON 0V
PS-ON 0.16V
GND

voltages from PSU to Main-board:

PS-ON 0.16V
STBY 5.25V
GND
D15V 14.76V
GND
GND
D5.3V 5.25V
D5.3V 5.25V
GND
D15V 14.76V
D15V 14.76V
D5.3V 5.25V

is this any more help to understand whats wrong ?

[tom66]

Re: Samsung PS51E450 Plasma Problem.

Please check VS as the TV cycles on, note any changes; use the highest DC range.

And then check VSON, VS_CON, PSON.

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

ok Tom i realy think this one is going to confuse... i had to try it 3 times ju to make sure i wasnt wrong..put red probe on VS_ON and plugged in tv. jumped to 2.33V then down to 0v. with VS_CON it went to 0.82v then straight down to 0v, now this confused me put red probe on PSON and it was 3.68v and as soon as i plugged tv in it shot down to 0.16v, should tv have that voltage unning through it when is not plugged in or is that normal ?

[tom66]

Re: Samsung PS51E450 Plasma Problem.

A power supply stores a lot of charge. It's easily possible for the outputs to remain available for up to a minute after unplugged. PS-ON is pulled up HIGH by a resistor from the standby rail. It is normal for PS-ON to go low when the TV turns on. (This operation is reversed compared to other power supplies where a HIGH signal turns them on, it is known as ACTIVE-LOW signalling. However, confusingly, the VS-ON is ACTIVE-HIGH, which means it must go HIGH for the PSU to turn on the Vs & Va.)

[Mikeyboy2007]

Re: Samsung PS51E450 Plasma Problem.

what could be causing the low voltages. is it those 3 voltages are stopping the tv from functioning ?

[tom66]

Re: Samsung PS51E450 Plasma Problem.

I need you to check the Vs first to say if they are good or bad.