Viore PD50VH80 50" Plasma`

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Well some progress here found the D5.3V output pins all show a short to ground (around 22 ohms), now I can search for it..

[tom66]

Re: Viore PD50VH80 50" Plasma`

I can't see a short on the outputs causing no voltage on the primary side, but maybe there's more than one bad component or some test is going wrong.

That chip you linked to produces standby and main power (15V/5.3V.) Does not produce Vs or Va.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Also all the pins on the 'cold' side of the transformer TB801S show a short to cold ground, am I doing something wrong here or is there something majorly wrong. I can't find anything obvious..

[tom66]

Re: Viore PD50VH80 50" Plasma`

Also all the pins on the 'cold' side of the transformer TB801S show a short to cold ground, am I doing something wrong here or is there something majorly wrong. I can't find anything obvious..

That is normal... a transformer is a bunch of wires around a magnetic core. The wires are wound in coils which are inductive, they have almost zero DC resistance but differing properties when driven at high frequencies, in switch mode power supplies.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Ok then, how bout this one then, this 28 pin IC on the bottom, has a short to ground on VSS pins 8 and 19. Could that be it? I don't see a ground pin on that IC though?

[tom66]

Re: Viore PD50VH80 50" Plasma`

Vss = GND. That is the MICOM for controlling the power supply sequencing. Is strange to see Samsung using a PIC micro, I remember using them in a project a while ago.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Great.. lol OK then I dunno I checked all the diodes and transistors on top, and a lot of stuff on the bottom Ill give it one more look then I'm done with it..

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Would there me any reason that I SHOULD have 24 ohms to ground from D5.3V line or is that definetely a problem?

[tom66]

Re: Viore PD50VH80 50" Plasma`

It doesn't sound right, do you have a bench supply? Apply 5V to their and see if a short still appears present.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Actually just got a current limiting power supply, haven't used it yet.. What should I set current to?

[tom66]

Re: Viore PD50VH80 50" Plasma`

50mA max for now, 0.05A. Should be enough for the control circuit & not much else.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

It seems OK, I set it to 5.3V, but it doesn't let me increase mA over 220. I have the 5.3V at the pins, and I hear the relay clicking when applied.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Tested the cap with 5V applied and still nothing, I ordered a new PS board..

[tom66]

Re: Viore PD50VH80 50" Plasma`

220mA should be enough to make something warm very quick.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Well got new PS board today, TV powered up!

Had sparkles, had to adjust Vs up a little from 209 to 213, still sparkles. Va is good.

Ve says 89 on sticker, getting 101V. Turning VR-VE on X-Main makes no difference in voltage however by turning clockwise I was able to get rid of the sparkles.

Not sure this was the correct technique though??

[tom66]

Re: Viore PD50VH80 50" Plasma`

Do you have Yrr/Yfr adjustments? Set Vs back to panel stock or it may buzz more than it should do or shutdown on bright scenes. You probably were adjusting -Vsc at the same time, as they are proportional to each other on these newer Samsung panels.

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Hey Tom, here are all the adjustments..

Vs and Va and were straight forward.

As I said Ve shows 89 on label but I actually have 101V and the turning the adjustment clockwise eliminated the sparkles but did not change the voltage.

Can you walk me thru the adjustments on the Y-Main and Ve? Thanks!

Also I noticed the TV shut off a couple times when first turning on, I wasn't sure at first if I did something or hit the power cord, maybe some voltage is outta whack?

[tom66]

Re: Viore PD50VH80 50" Plasma`

If Vs and Va are too high the TV can sometimes shut off due to excessive power consumption.

Ideal scene test pattern with colour bars, then verification of image retention on scrolling pattern (use service menu.) Finally, verify full white performance and check for pink maldischarge.

Adjustment:

• Set Vs and Va to panel spec.
• Set Vsc (VR-VSCAN) to panel spec.
• Try to set Ve (VR-VE) to panel spec.
• Observe display for sparklies. There are several different types:
  • Negative sparklies (stuck dark pixels): Adjust VR-FR first then VR-RR.
  • Positive sparklies (flickering lit piels): Adjust VR-FR.
  • Image retention (sticking pixels): Adjust VR-RR then VR-FR.
• Should above controls fail to help with sparklies, proceed to adjust VSCAN, VE and VS as below:
  • Negative sparklies: Increase VS, VE, make VSCAN more negative.
  • Positive sparklies: Drop VS and VE.
  • Image retention: Tweak VSCAN/VE.
• On full white scene do you get pink maldischarge? If so, increase VS by a few volts.

NEVER adjust Va, other than to set it to panel spec -- excessive Va kills the panel!

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

Ok I adjusted Vs, Va, Ve, and Vsc to panel spec. I was making a mistake and using the Ve pin on the connector instead of the test point, so now I've got everything good.

I had some image retention I played with the FR and RR a little, is there anything other than looking at the picture to those adjustments?

Im watching it now and so far so good I may be done with it! Thanks!

[kevinm34232]

Re: Viore PD50VH80 50" Plasma`

There is still image retention when watching something with a fixed image, and then changing the channel you see the image and sparkles for a couple seconds where that image was..