Panasonic TH-42PZ85U No Picture

[coreyand]

I picked up this th-42pz85u the other day. Took it home and plugged it in. The screen lights up up but I dont get any display, no OSD or anything.

I followed a FSM on the tv that pointed to the D board. So I replaced the D board. I still get the same result, screen lights up but no display.

The next thing Im thinking of is replacing the A board, being as this is the most expensive board on the tv that I would have to replace I wanted to get some input from the pros here before I just ordered the board, I made that mistake with my TH-50px75u replacing the SS and SC and D board to discover it was the SD board being the problem all along.

Would replacing the A board be what controls the picture to screen or generating the picture to the screen, I imagine it is and I apologize if my questions sound like kindergarten stuff for you guys. Believe it or not Ive repaired quite a few tvs from information gathered here but that was on LCD tvs.

Ive come to discover a whole new world of troubleshooting and fixing plasmas, and that discovery is that their a headache.

Anyway any input soon would greatly appreciated, theres only one A board that matches my model tv available on ebay on right now. I would order it but as I said its expensive and I wanted to see if there are any other things I can do first before assuming its the A board.

One thing I have done in the flow chart was unplug the cable going from the A board to the D board which resulted in a blank white screen instead of black, thats about the only change in the picture I have been able to produce.

Thanks guys yall are awesome and a huge help for an amateur like myself, I am learning slowly with each set I repair and find myself not needing to look for answers right away in some cases but these plasmas just really got me.

The part number of the A board is TNPH0721S and my model of the tv is TH-42PZ85U.

Thanks again.

[tom66]

Re: Panasonic TH-42PZ85U No Picture

There is a test you can do. Disconnect all connections from the A board. Everything disconnected. Plug the TV in and turn it on. If everything else is working, set will turn on with a full white screen. There will be no power light and you can only turn it off by unplugging it.

This will confirm A board is bad.

[coreyand]

Re: Panasonic TH-42PZ85U No Picture

Thanks Tom I will check that to verify and If I get a white picture I will be ordering the A board, It would seem there is only one available in the whole nation on ebay for this specific set right now.

[coreyand]

Re: Panasonic TH-42PZ85U No Picture

Tom I unplugged absolutely every connection from the A board, The tv turned on, on its own and the screen was solid white. So I am guessing this is confirming the A board is bad and with place a order for the one I have found, then comes the waiting part for the parts for this tv and my TH-50PX75U. Sigh, plasmas...I swear lcd and led is easier to work on.

[coreyand]

Re: Panasonic TH-42PZ85U No Picture

Well I got a new A board in today and hooked it up and voila! Picture is working and everything is good minus one thing. The board they shipped me had bad HDMI plugs. Ive contacted the seller of the board in hopes they will either refund me my money or ship me another board in good condition. All other inputs work however. So I narrowed down the problem on this plasma thanks to you guys' help. Ill post an update when I figure what they want to do with the faulty board they sent me.

Quick question, anyway of of taking the HDMI ports off my old board and putting them on this one, looks like they were put on by machine and near impossible to change out, unless there is a plug and play option of some sort? Heres a pic.

[mmartell]

Re: Panasonic TH-42PZ85U No Picture

Looks to me like that board was baked - a little too high or a little too long. Any other evidence of plastic deformation anywhere ?

[coreyand]

Re: Panasonic TH-42PZ85U No Picture

None at all, It works thought. I managed to straighten out the pins on HDMI 1 and got it to work, oddly enough HDMI 3 is a remote port on the side of the tv connected with a pin cable internally so you would have assumed that one should work no matter what. But it didnt, even after I got number HDMI 1 working. I straightened out the pins thinking that them touching eachother was causing HDMI 3 not work like shorting it out but ended up getting lucky and fixing one of them. Luckily the seller refunded me in full for the board because of the defective ports.

But I agree it looks like it had been reflowed and baked too long. Oh well the tv has gone to a happy new home now and I put a couple of benjamins in my pocket.

[mmartell]

Re: Panasonic TH-42PZ85U No Picture

Very good, thanks for the follow-up.