Panasonic TH50PZ80U - power button

[ultimatt]

picked up a TH50PZ80U for free...does not work.

Plugged it in and it does nothing...no lights...no sounds nothing.

Took the back cover off an all boards are there and all connections tight. No blown caps.

The power button seems like the spring may be broken inside.

Here is my question - if there is some sort of problem with the power button will the set not fire up even with the remote? Confirmed the remote worked on my other TV.

If it will not fire without a functioning power button is there some way to jump it to get it to fire? Is the spring available as easily replaced?

Would like to confirm this is the only problem before I dive in too deep.

Thanks.

[freakaftr8]

Re: Panasonic TH50PZ80U - power button

First of all when you plug it in to hear any clicking on the power supply? Next thing I'm wondering are you receiving 5v standby from the power supply

[tom66]

Re: Panasonic TH50PZ80U - power button

If the power button is not pressed the set will act dead, even the 5V standby from the PSU will be missing. The button sends a signal to the power board which enables the standby voltage.
You can try bypassing the button for now by shorting across the two wires on it. It is connected to the SS board through a 2 pin cable, the SS board then routes the signal to the P board.

[freakaftr8]

Re: Panasonic TH50PZ80U - power button

That's right. Older panasonics. I almost forgot.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

right...no click when it is plugged in ...nothing...

going to do as tom suggested and short across the two wires to see if I can get it up.

If it is just the spring that has failed is that repairable?

Thanks...

[tom66]

Re: Panasonic TH50PZ80U - power button

That's right. Older panasonics. I almost forgot.

Even newer Panasonics (at least up to 2011) will act dead (no standby or clicks) with the power switch off.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

since it is late in the day just thought I would ask...

IF jumping the wires does not produce power what would be the next thing to check?

What are the possible problems? I had another 50PZ80U that I fixed (10 blinks) and every time I plugged it in I would get and audible "click", but with this set I get nothing.

Could it be the power transformer itself? Is there a way to check it?

Although the cord shows no problems I am going to switch it out for a known good one just to eliminate that as a source of the problem


Thanks.

[tom66]

Re: Panasonic TH50PZ80U - power button

Check 5V standby. If that's present and the set is still not lighting the LED then the A board is defective in some way.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

does anyone have a link to a service manual?

[tom66]

Re: Panasonic TH50PZ80U - power button

Check the link in my signature.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

found one...thanks..

per the 6.3 no power flowchart a "no lit" condition would indicate you check the "p" board...is it referring to the "p" main or the "p" AC or both...

since the power goes into it first...what should I look for on the "P" AC board?

Thanks.

[tom66]

Re: Panasonic TH50PZ80U - power button

Before you even go there just check the 5V standby on one of the connectosr to the A board. Marked 5VS.

If it is missing then that would be a power board fault, or the switch. Since 5V generated on P(AC) look there first, although it then gets transferred to the P(MAIN), which switches it on and off as the power switch requires.

If it is present then look at the main board.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

alright..decided to go back to class 101 - check fuses.

All had continuity except for 1 on the "P" AC board - see red box in attached pic.

Is this a fuse that can be had off Mouser or Digi-Key or is it some Panasonic magic fuse?

Does anyone have a link to the proper replacement?

don't know if this will be the only issue...but hopefully...

Found this TV out by the curb in the neighborhood..neighbor said "it just quit working so we got a new one"..if it is just the fuse I think I will offer to give it back if they want it..

[tom66]

Re: Panasonic TH50PZ80U - power button

Probably something else is wrong, fuses rarely blow without cause. It can happen, it's just unlikely.

You can try putting a light bulb across the fuse - 100W or so - attached to wire clips - if it glows then there is a problem. If not, set may actually turn on although I doubt you'll get to the stage of having a picture with the bulb in place. But then you can replace it and test it again.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

any idea what that particular fuse is protecting?

[tom66]

Re: Panasonic TH50PZ80U - power button

That protects the entire TV. It's one of a pair of main input fuses.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

interesting...we had bad storms here of late wonder if it got hit?

Do they work in series or parallel?

guess I will order 2 fuses in case there are larger issues...

[tom66]

Re: Panasonic TH50PZ80U - power button

The fuses work in series, one for live and one for neutral.
Lightning rarely causes fuses to pop without doing other damage. However fuses can sometimes fail without obvious cause.

[ultimatt]

Re: Panasonic TH50PZ80U - power button

guess I will replace the fuse and see what happens...at least at that point I will only have a few $$ in it...

Thanks for your help Tom

[ultimatt]

Re: Panasonic TH50PZ80U - power button

OK, got the fuse problem sorted on the power (ac) board.

Plugged the unit in and immediately got the "click" to indicate it was getting power. I immediately unplugged it.

So, I solved the fuse problem, but the question remains "why did the fuse fail"?

Is there a way to set up a DMM on the unit to tell if it has a fault that will blow the fuse?

I would assume if it does I may have five seconds or less to determine that before it blows..

Thanks