Panasonic TC-p58s2 no power

[TechShui]

Hey all, happy holidays

I'm working on a panasonic viera wth what so far appears to be a faulty power board. This has two power boards- a master and a sub ppwer board and i need help isolating which one is the problem.

So far i havent done much, what surprises me is the lack of wires in this plasma, i've never seen one with only two plugs, where does the main board get its power? I guess its routed thru one of the sustains? But i dont see any wire coming off those

Anyway back to the task at hand, i've tested the voltages on the two plugs, which lead to the z-sus qnd y-sus respectively. The both have one gray wire and four brown ones. The grays are around 2 or 3v with the the TV off. However with the TV power button pressed, I briefly register 170 to 180v on both gray wires, and it QUICKLY starts to drop all the way down to 3v again.

All the browns are 0.0v, so I assume those are gnd.

Disconnecting the sustains does not affect the readings.

The power led on the front blinks reds continuously, and only way to make it stop is unplug the TV.

I havent check the bridge rectifier yet, but i will do that and report back my findings.

[tom66]

Re: Panasonic TC-p58s2 no power

How about pictures of the boards?

Also, does the LED show a blink code, or none at all?

It's not going to be the bridge rectifier as that would blow the fuse.

[TechShui]

Re: Panasonic TC-p58s2 no power

You're right, the fuses are good. There are 4 fuses on the main power board and they're all good.

The power LED blinks continuously, there's no pattern, no pause.

Unfortunately I don't have photos of the main power board since I left it at home, but in a couple hours I'll be there, so I'll upload a pic.

Here are the rest of the boards.

Can someone explain to me why the sustain boards don't have fuses? I don't even see an SMD fuse, this makes it harder to rule those boards out.

[tom66]

Re: Panasonic TC-p58s2 no power

Red LED blinks once every 3 seconds? "No specific check point"

There are no fuses because:
a) it's very rare for Panny SC/SS to short to ground
b) the fuse is usually saved by the semiconductor, not the other way around
c) they cost money & don't do anything useful (see a, b)

[TechShui]

Re: Panasonic TC-p58s2 no power

Hmm, more like every second

A couple more observations:

- the relay seems to click twice
- The spike and than drop in voltage seems to indicate it's on at at full power for at least a second or two.
- Can I state the obvious? The power board is probably going into protection mode

The million-dollar question is why?

EDIT: is there anything on the Sub Power board you want me to check?

[tom66]

Re: Panasonic TC-p58s2 no power

Do you get Vsus when SC, SS disconnected?

[TechShui]

Re: Panasonic TC-p58s2 no power

Yes, it's about 180v

There's no plaque inside the TV with the voltages listed, but I'm searching for the service manual right now...

EDIT: This might be it,

[tom66]

Re: Panasonic TC-p58s2 no power

There's one on the top right. Panel sticker with panel model number. Should have Vs, Ve and maybe Vda/Va.

[TechShui]

Re: Panasonic TC-p58s2 no power

I've finally attached a photo of the main (master) power board. And I'm reposting the subpower board this time in the proper orientation.

Is there any way to isolate which board is bad?

[tom66]

Re: Panasonic TC-p58s2 no power

Looks like there are two separate Vsus supplies, plus a Vda supply. Make sure each Vsus and the Vda are good.

[TechShui]

Re: Panasonic TC-p58s2 no power

I ordered the main (master) power board, took a long while to locate one at a reasonable price and i am very disappointed to say It did not fix the problem.

At this point I'm really worried that this falls into what you call a rare phenomenon: a shorted Y or Z board.

How can I rule them out? Please help, I don't want this to turn into a money pit

Btw, I read your post in the FAQ forum, about using a remote to send diagnostic commands to the D board. However my screen shows NOTHING, no "primed" panel, no glow.

[tom66]

Re: Panasonic TC-p58s2 no power

Well, if it helps, this TV uses two Vsus supplies, one for each side of the plasma panel (one for SC, one for SS.) So if you measure Vsus on one side but not the other then your suspicion should lead to that side.

[TechShui]

Re: Panasonic TC-p58s2 no power

The Vsus is supposed to be 180v right?

On both Vsus supplies I'm briefly getting 180V on my multimeter then it quickly DROPS down to 3V.

This doesn't look good, could this mean both SC and SS are shorted? Something is loading down these voltages. But what exactly? A blown mosfet...?

The only other plasmas I've worked on had IPMs, this Panny is all VRs and rectifiers.

[tom66]

Re: Panasonic TC-p58s2 no power

Vsus is indicated on panel sticker along with Ve.

A shorted SC/SS would be 0V on one supply.

Please note, this TV has two Vsus supply. One for SC, one for SS. Not combined.

So the fault must be common to both supplies, which probably indicates a SOS detect. Have you checked for a blinking LED?

[tw2005]

Re: Panasonic TC-p58s2 no power

The Vsus is supposed to be 180v right?

On both Vsus supplies I'm briefly getting 180V on my multimeter then it quickly DROPS down to 3V.

This doesn't look good, could this mean both SC and SS are shorted? Something is loading down these voltages. But what exactly? A blown mosfet...?

The only other plasmas I've worked on had IPMs, this Panny is all VRs and rectifiers.

As soon as the TV faults, it shuts down. What you're seeing I believe is normal. If you've isolated the VS lines from both the SC & SS and the fault code did not change from SOS1 then I'd be thinking A-board.

I'm pretty sure there are no longer Panel voltages labelled as the Vsus is now controlled by the A-board in the service menu with 2 settings low & high.

[tom66]

Re: Panasonic TC-p58s2 no power

Panasonic have got the precision of the panel manufacture down to an art of only using Vsus and Ve, but I thought they still specified them.

[tw2005]

Re: Panasonic TC-p58s2 no power

I've got nothing mentioned for the 13th gen model for voltages of the panel, first thing i noticed last year for this P50V20 I have which puts you off when you're trying to sort out the PSU.

In fact the only adjustment it mentions is the VSUS in the service manual. I know there's adjustment pots on the PSu but they're not telling me much, maybe factory set??

An accurate response for the blink code would help although I thought you'd already alluded to 1 blink, maybe I misread. One thing's for sure if VS was dead short then he would not see it rise to 180V.

[tomwil]

Re: Panasonic TC-p58s2 no power

An accurate response for the blink code would help although I thought you'd already alluded to 1 blink, maybe I misread.

Wouldn't the 1 blink be associated with the A-board, as described in this document?

[tw2005]

Re: Panasonic TC-p58s2 no power

Wouldn't the 1 blink be associated with the A-board, as described in this document?

Reading through the post it's unclear to me whether the OP has clearly been able to identify SOS1 or not. I'm thinking the way it's described it probably is because he mentions continuous blinking with no pause but on a single blink it could be interpreted that way.

2 blinks or more and at least you see a break as the blinks for the code are faster then a pause and repeated until the set is turned off.

I already mentioned the A-board for SOS1 so I'm not sure what you're asking??

[tom66]

Re: Panasonic TC-p58s2 no power

I have to say 180V is extraordinarily low for this generation of panel -- should be closer to 200V.