hitachi/pioneer 50" plasma power supply

[cadiman]

I have a hitachi(pioneer) pdu50wx2a plasma I have tried to find schematics for the tv under both names and I do find them, but they don`t show the power supply. These boards were a class action lawsuit for pioneer. The new board is an axx 1064 the old board was an axy 1059. I replaced the mosfets and a .1ohm fuse resister. I was missing a few of the low voltages after repair. This is a double printed curcuit board, It should be an easy fix for me, but I have never felt so dumb. These board all have the same problem so if I fix one, I fix them all. I don`t understand the curcuit layout yet. All the caps are the good stuff and seem to test ok using my dvm (none shorted or open) and do charge up. This board lasted a long time (2003) for a faulty board. If I had a real service manual I would have been hanging this thing on my wall by now! I can buy a board on ebay, but I can`t sleep until I fix this thing! I should have stayed in college longer.

[PlainBill]

Re: hitachi/pioneer 50" plasma power supply

I have a hitachi(pioneer) pdu50wx2a plasma I have tried to find schematics for the tv under both names and I do find them, but they don`t show the power supply. These boards were a class action lawsuit for pioneer. The new board is an axx 1064 the old board was an axy 1059. I replaced the mosfets and a .1ohm fuse resister. I was missing a few of the low voltages after repair. This is a double printed curcuit board, It should be an easy fix for me, but I have never felt so dumb. These board all have the same problem so if I fix one, I fix them all. I don`t understand the curcuit layout yet. All the caps are the good stuff and seem to test ok using my dvm (none shorted or open) and do charge up. This board lasted a long time (2003) for a faulty board. If I had a real service manual I would have been hanging this thing on my wall by now! I can buy a board on ebay, but I can`t sleep until I fix this thing! I should have stayed in college longer.

As always, pictures help. These board are a pain to work on. There are multiple supplies, and they are interconnected so they start up either in sequence or within a certain time of one another.

In general, there are three stages to these supplies. There is the PFC front end; there are several interconnected regulators generating with both regulated outputs and unregulated voltages, then there smaller DC-DC converters running off the unregulated voltages.

The way I would approach it is to first figure out which transformer is responsible for the missing voltages. Next, is it a problem on the primary side of the transformer, or is it a problem with the one of the regulated or unregulated outputs? If it is on the primary side, is it being 'locked out' by the control from another regulator, or is the SMPS itself defective.

PlainBill

[Wizard]

Re: hitachi/pioneer 50" plasma power supply

If this had a recall/service bulletin, that board is *defective by design*. Replace it.

There is a fault built into the circuit board taken together that caused parts to fail more than usual. You're lucky that happened much later.

There are no schematics at all for plasma sets. Board replacement level.

Cheers, Wizard

[cadiman]

Re: hitachi/pioneer 50" plasma power supply

I was waiting for the two of you to step in with your comments! Where should I send the party trays? Past experience has shown me that food gets alot of smiles as well as information and yes I am italian! Food is as important to me as electronics. I feel a little smarter so thanks! I knew I was in over my head.

[cadiman]

Re: hitachi/pioneer 50" plasma power supply

I found an axx1064 updated power supply on ebay for 200 bucks. I now have an 8 year old plasma on my wall. This pdp is very bright even with the settings at 50% with no screen burn to be seen anywhere. The sound is great too.

[SlickClick]

Re: hitachi/pioneer 50" plasma power supply

Well I got PDP-433CMX in a package deal; when i first opened it; i saw the ymain had 2 swollen caps; found a good ymain locally for $15 so put it in... went to fire it back up... nada same 5 blinking light crack it back open start doing tests on the power supply dead as a rock not a click buzz nothing but a red light on it steady...

Now is when it gets interesting; after seeing these boards are hard and pricey to get i began to try and test out the board... as bill said i found that there is multiple ground circuits real pain to work with trying to find a short... which is what i ended up finding... this power supply has a short across the ground and the 6.5v CH2 test lead -all test done with board off aluminum tray and on bench- going along the circuit i find that the caps along it on the negative side are all shorting on the 6.5v leg... later i found the R371 is open; doesnt look burnt or bad at all but its surely isnt passing anything so i jumpered it for testing sakes and low and behold the 15v leg now shorts to ground too...

I read a russian site on this board but they speak of R133 blowing up and a batch of transistors and resistors in the Q120 area and the D145 areas but my board has none of these blown or shorted -at least not shorted across the component itself- as far as i can test or see... the copper heat sink on DU106 shorts to 6.5v and now with the jumper across R371 15v shorts too...

Without a schematic diagram or test probe location values this board is a nightmare to reverse engineer... any ideas..? im leaning towards a bad transformer; what else could open R371 and cause 6.5v to short to ground..?