Philips 42PF7320A/37 42" Plasma Repair

[stevekasian]

Re: Philips 42PF7320A/37 42" Plasma Repair

I have removed the Y and both buffers. I see on the Coppel blog how to check the buffers, but I see nothing related to checking the Y board other than a small entry regarding checking the IC.

I have checked the IC pins as directed and they are not shorted. I've also checked the 3 FETs (witht he 3 smallest heat sinks on the board) and they appear to be in working order.
Before I go through the arduous task of de-soldering the heat sinks and checking the TO-263 ICs (as my soldering iron is just not quite hot enough to efficiently heat larger pins), is there anything else that you can advise as to how I can make sure the Y board is not burned?

I seem to remember reading something somewhere about checking the power pins on the input side of the Y to get an impedance reading, but for the life of me I can't figure out where I read that. :-(

As for the buffers, I've checked them as per recommendations in the cooper page referenced previously. The lower board is shorted, so it's obviously burned. The upper board, however, doesn't show a reading other than in diode test mode. In that mode, it reads nothing one was and .784 the other. But I get no readings all the way up through the 2M ohm scale. Do you know what this might indicate?

Furthermore, I've reintroduced the Y-Sus board into the circuit w/o buffers, powered the unit up and checked all voltages on the same rails as before. All voltages are correct and steady. Don't know if this tells me anything about the condition of the Y board but there it is.

Thanks,
SK

[PlainBill]

Re: Philips 42PF7320A/37 42" Plasma Repair

Short story: If a buffer is shorted, one of the IXTA36N30P power fets under the heat sink is shorted. The recommended approach is to replace both buffers and the Y-sustain. Or you can replace all 12 buffer ICs and the shorted IXTA36N30P transistor on the Y-sustain. The parts are available relatively cheaply - as I recall the transistors are about $7 each and the ICs are $9 each.

There is one more blog entry on these boards.

PlainBill

[stevekasian]

Re: Philips 42PF7320A/37 42" Plasma Repair

Thanks.

I did check the leads on the transistor under the heat sink, as outlined in the cooper article, and it is not shorted. Nor was the fuse on the Y blown, which they say is what usually happens when the IC goes.

Does this mean anything, or am I still stuck with replacing the Y-Sus for practicality reasons?

[PlainBill]

Re: Philips 42PF7320A/37 42" Plasma Repair

Thanks.

I did check the leads on the transistor under the heat sink, as outlined in the cooper article, and it is not shorted. Nor was the fuse on the Y blown, which they say is what usually happens when the IC goes.

Does this mean anything, or am I still stuck with replacing the Y-Sus for practicality reasons?

I've dealt with three TVs with this problem. NONE of them had a blown fuse on the Y-sustain, so forget that 'proof'.

Yes, it is possible that none of the transistors are shorted and the Y-sustain is good.

Remove the shorted buffer, then hook up the remaining good buffer and y-sustain. Turn on the TV. If you get a picture on half the screen you got lucky.

If you don't, do yourself a favor, put the TV back together and sell it 'For parts or Repair'. Unless, of course, you relish the prospect of replacing 12 ea 100 pin ICs, and one TO-263 transistor that is between good ones.

PlainBill

[rayrod81]

Re: Philips 42PF7320A/37 42" Plasma Repair

Just so you know, I have had Y-sustains on these models that are bad with no indication of being bad. There are no shorts or obviously bad components on the board but the board will fail almost immediately the next time it is run in the TV and take the buffers with it. If you buy new buffers or replace the ICs on the existing ones and put them in the TV with original Y-sustain there is a good possibility you will fry them as soon as the TV is powered on. I have a test set of buffers just for this possibility and it has saved a lot of headaches and money.

[stevekasian]

Re: Philips 42PF7320A/37 42" Plasma Repair

Thanks guys. I do appreciate all your help and information very much. I have learned a LOT through this process. Most importantly, I've learned that plasmas aren't nearly as complex as I thought they were, and that I can repair them provided said repair is cost effective.

This one obviously is not and, as such, is going up for sale 4 parts.

Thanks again!!
Steve

[rmoody]

Re: Philips 42PF7320A/37 42" Plasma Repair

Thanks guys. I do appreciate all your help and information very much. I have learned a LOT through this process. Most importantly, I've learned that plasmas aren't nearly as complex as I thought they were, and that I can repair them provided said repair is cost effective.

This one obviously is not and, as such, is going up for sale 4 parts.

Thanks again!!
Steve

try a LCD, they are much simpler.

[PlainBill]

Re: Philips 42PF7320A/37 42" Plasma Repair

try a LCD, they are much simpler.

Not really; they have different problems. Rather than a bad sustain you have to deal with bad tcons, bad panels, inverter or CCFL problems, power supplies with absolutely nothing labeled, etc.

Both are repairable (although not necessarily economically), the important requirement is someone who understands what he is doing, and why.

PlainBill

[stevekasian]

Re: Philips 42PF7320A/37 42" Plasma Repair

Yeah, I decided to tackle LCDs because I found an Ebook online by Yunyeeshuyee or whatever his name is called "LCD Monitor Repair". I picked it up, read it and when i realized how simple they were I jumped right in. (I always made sure to avoid plasmas, because they were such scary, complex animals - or so I thought.) Then I found THIS amazing place, with all of you who are so helpful, and managed to repair quite a few LCD TVs and monitors.

I had a friend give me this plasma the other day and I didn't even think for a second I would try to repair it. But then I opened it up just for the heck of it and realized it's all just chassis and screen. 95% of the weight is stuff other than the circuitry. Then, after PlainBill put me on the path to the various manuals for the thing (thank you VERY much!), I learned that they're not so scary after all; A bit more complex in certain ways, but mostly just different. Certainly nothing like an old CRT television set from 1980 though, with crazy high voltages and capacitive tubes that can kick you all the way across the room if you accidentally touch one b4 discharging it. No thank you to all-a that noise!

Technology is a wonderful thing :-)

Thanks again guys,
SK