Panasonic 50" power supply, no standby +5V

[Nicholas]

Hi guys, totally new here! Though, I have used information about
caps from this site over the years.

I just got a defective Panasonic P50XT50Y plasma TV, that is totally dead;
no lights no nothing. I check the power supply and there is no standby +5V.
There is 220V in, this goes to the bridge rectifier and gets out as 320V DC.
This 320V DC goes to the transformer, that I understand should output
something that would end up being the standby voltage. However, nothing
is on the other legs of the transformer(Darfon 1151 S)

I have attached a picture with text!

Any advice about what I should do?

Thanks,

Nicholas

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

https://www.badcaps.net/forum/showthread.php?t=36055

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

Thanks! It seems to already have been changed by the previous owner...I wondered
why he had changed that!

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

Thanks! It seems to already have been changed by the previous owner...I wondered
why he had changed that!

unless they tried it and it did not fix? or re-occurence?

I wonder if it's possible to retro fit maybe a different model PSU(previous gen) if these things are so unreliable?

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

Oh, it's a PSS, combined psu/ss board. crap.

[sordids999]

Re: Panasonic 50" power supply, no standby +5V

The board looks the same one I fixed the other day no 5v standby tv totally dead changed u203 all working again

[Neelix]

Re: Panasonic 50" power supply, no standby +5V

Me also replaced U203 the other day and got the TV working again, but in one spot the etching slightly lifted when I removed it and formed a small bubble because of the heat from the hot air gun

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

Okay, it seems I should give U203 a shot then...I'll take a picture of the previous
work on it. It is HORRENDOUS. I hope I can fix it.

Thanks a lot!

Nicholas

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

Here you go:

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

Here you go:

OMG. looks very bad, dodgy and I wonder if the cct has been modified or jumpered. looks very wrong. also in that pic R410 looks sus as if it has a hole in it. I'd check that and the diode next to it. maybe it has not been replaced but attempted bypass or something ??

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

The R410 and the diode next to it looks fine, no holes or anything.

What is my course of action? Should I remove the hack-job, remove solder then sand
the area to see what the real world beneath looks like?

Also, could I test the TV set with an external +5V source, for standby voltage? If I
lift the STBY5V test point and the GND next to it, and attached leads to a 5V supply?
Just to see if the standby voltage is my only problem.

Thanks!

Nicholas

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

The R410 and the diode next to it looks fine, no holes or anything.

What is my course of action? Should I remove the hack-job, remove solder then sand
the area to see what the real world beneath looks like?

Also, could I test the TV set with an external +5V source, for standby voltage? If I
lift the STBY5V test point and the GND next to it, and attached leads to a 5V supply?
Just to see if the standby voltage is my only problem.

Thanks!

Nicholas

never tried injecting 5v for stdby but might be worth a shot. I'd definitely remove all those rediculous jumpers and dewick it so it's neat. probably safe to assume that IC is dead hence it being butchered.

IC like that should be easy to get off. If you have 2 irons you could flow solder both sides and heat at same time and get it that way .

I would only carefully dewick those pads, no sanding, inspect the traces, get a new Ic. Does not take too much heat for pads to lift.

that's how I'd attack it. have you found the Darfon schematic to see how that IC ties in with the cct?

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

after dewicking, if you have isopropyl alcohol to clean it up nice for a good look.

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

I'll do that, remove it since it is not trustworthy as it looks now
Where do I get another IC for U203?

Schematics are not my strong point, haven't even looked for them.

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

I'll do that, remove it since it is not trustworthy as it looks now
Where do I get another IC for U203?

Schematics are not my strong point, haven't even looked for them.

ebay, china, google.

or PM

PowerAmpFreak who is in Sweden and verify the exact part number he used as i think there are 2 versions. He may have a good advice for where.

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

https://www.badcaps.net/forum/showthread.php?t=36055

Thanx TW2005, you Panasonic expert!
The PSU is the '06 model and the U203 controller is the 6755.
I will go for the FAN6755U and try it out.

https://www.badcaps.net/forum/showth...light=tc-p42x5

Glad I came across this forum! Panasonic TC-P42X5 plasma won't power on anymore after a power cycle. Only two year old. Checked fuses, were fine. Measured voltage at Vdd and got nothing. Figured the power board. Almost pulled the plug on a power board from eBay for $80 but decided to do a little search and found this forum. Went ahead and ordered a couple of FAN6755U (U203)from eBay for $3. Just got Em and replaced it on the board. Lo and behold, tv is up and running. Thanks Guys!!

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

Awesome, thanks!

Ordered, will report back when installed(or failed to install if previous work mangled
the board)

[tw2005]

Re: Panasonic 50" power supply, no standby +5V

Awesome, thanks!

Ordered, will report back when installed(or failed to install if previous work mangled
the board)

worth a shot, not too expensive i believe

[Neelix]

Re: Panasonic 50" power supply, no standby +5V

Must be the 6755UW one yes. The 6755W is for a different frequency

[Nicholas]

Re: Panasonic 50" power supply, no standby +5V

Ok, I'm ready for the external +5V test(for standby voltage)

As seen in the image below, I cut open the jumper and soldered the +5V, so it
only goes out to the main board, not back into the PSU. I soldered the GND to
the GND test point (did not cut it open )

Should I test it in the TV now? Any reason it would do something wrong?

Thanks!