Pioneer PDP-502MX Power problem

[moldymac]

I have a 50" Pioneer plasma set that will not power up for me. When plugged in, you get a solid green power light, you hear a click, then the light starts blinking and goes solid again. Nothing comes up on the screen and the fans won't spin. I opened it up to find after the light stops blinking a red LED on the power supply board comes on labeled "MAIN". The other LEDS are off. I called Pioneer and unfortunately they no longer offer the free power supply replacements for this tv. The agent I spoke to said that light does mean a power supply failure. Has anyone had any luck fixing the power supply on this tv? None of the caps appear blown on it, I'm not too sure where to go from here. Thanks!

[Dgtech]

Re: Pioneer PDP-502MX Power problem

Post a couple of clear photos of this power supply board - front and back. I'm sure there's someone here that can help you. If it's a set that is known for that failure, I'm almost certain there's got to be someone that will chime in to help you. Also with the photo's, post any numbers on the board. That could be helpful also because sometimes these power boards are used in multiple models.

When posting pictures, use "Manage Attatchments" on the posting page.

Good luck and welcome.

[moldymac]

Re: Pioneer PDP-502MX Power problem

I'll get some pics of the board. Hopefully someone knows something about this board, must be fairly common if pioneer started a replacement program.

[moldymac]

Re: Pioneer PDP-502MX Power problem

I got the board out, heres some pics of it. Every time I tried to upload it as an attachment it gave me a security error, so here they are hosted off photo bucket.
Numbers on the board:
Main Power Ass'y AWZ6506
Power Supply ASS'Y 1845-A A2UL06 (stamped)
On and edge ANP1966-A

[retiredcaps]

Re: Pioneer PDP-502MX Power problem

The photos allowed here must be 2000x2000 or less. And I believe the largest photo allowed is 2MB each.

[PowerAmpFreak]

Re: Pioneer PDP-502MX Power problem

Are you sure the powersupply is the problem?
What if you power up the psu alone, without connected Y-SUS and Z-SUS boards. Most of the PDP powersupplies has overload detection/shutdown, which will kick in if connected to faulty display power boards.
Have you tried to get hold of a service manual?

[PowerAmpFreak]

Re: Pioneer PDP-502MX Power problem

Please visit http://www.elektrotanya.com to find a service manual for the set.

[dziundzis3]

Re: Pioneer PDP-502MX Power problem

Hi, see an old theme of this TV.
Have the same model and etc. I have all most powered on the TV but one mistake burned out more parts. So now I have a problem. Realay turns on and then turns off and repeats it all over again. It doesne't matter what is going on on the board. I removed all RCC's and all OTL's it's still doing that. Everything what is working is STB power lines. It wont start other parts of power supply. Any LED showing an error, but it's only becouse of all power supply doesn't start. In schematic there is no many parts of supply so that makes it fix harder. Maybe some ideas about that?

If you still have that board would be great if you would say some parts of it. That would be:

Q203 it's near Q201 (first main transistor) - whats written on it. Is it BS or FR?
D234 it's on RCC (little board near Q201) - it's A or A5 or what?

I'm so close to starting it. Would be great to get some help...

[tom66]

Re: Pioneer PDP-502MX Power problem

I have fixed this PSU before. The FET for the Vs fails short, which burns out some of the pre-charge resistors. PSU will need FET replaced and pre-charge resistors replaced. (The white ceramic ones near the mains power in.)

[dziundzis3]

Re: Pioneer PDP-502MX Power problem

Already done that. Ceramic resistors are fine, changed one already. FET is schanged. Few days ago power supply was almost working properly.. I mean I didn't pluged the connector of Vsus and etc. it Showed an error with LED, but now it wont start at all.. The second relay RLY131 doesnt work for some reason I don't know..

[tom66]

Re: Pioneer PDP-502MX Power problem

Spray contact cleaner in the Vsus adjust pot, turn it a few times and try again, does it get better?

[dziundzis3]

Re: Pioneer PDP-502MX Power problem

The problem is that everything what is working is STB power no Vsus; ADR +10; +14 etc.. There is just +12 STB and +5 STB

[tom66]

Re: Pioneer PDP-502MX Power problem

I don't know then, I have had the MAIN switch off problem before on this plasma (in fact it's still in the shed, waiting to go to the dump!!) My one however has a white bar on the screen which is plasma panel failure, so it's not economical to fix.

[dziundzis3]

Re: Pioneer PDP-502MX Power problem

So maybe you can answer this?

Q203 it's near Q201 (first main transistor) - whats written on it. Is it BS or FR?
D234 it's on RCC (little board near Q201) - it's A or A5 or what?

That would be really helpfull. On my board q203 just gon by blowing up so I dont know what was the real one.. I putted an NPN there (BS) so.. That could be a problem of not turning on maybe?

[tom66]

Re: Pioneer PDP-502MX Power problem

Unfortunately, I'm about 400 miles away at university!