Panasonic Plasma TH-50PZ800U power supply light 2 blinks

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

Awesome thread! All you need to remember is that that tiny little SMD cap on the little upright boards MC201 and MC301 pictured, are the cause of the problem and remove that tiny little cap on each board. It seems to degenerate to a dead short status, which after being intermittent for a while eventually goes critical and drags the 15 volts at pin 1 of P7 down to nothing. Once removed that 15v comes right back to life - in fact to 15.85v on my set - the fans start spinning, and I get picture.

Simple! Just removed it from MC201 and am about to do the same to MC301, since they look to be identical boards. If it went bad on the 201, chances are it will eventually go bad on the 301.

So both are outa there!

Set is working magnificently, thanks so much to y'all!



Mr Bob

[tom66]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

Recommend replacing it with the electrolytic version. Removing it altogether might cause other issues.

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

I am sure you are correct, but I am going to chance it this time. Terryfictv has tried it and had no recalls, I am going to go with that.

A 1uF cap used for filtering will not do too much anyway, only the highest of high freq's - rf, and probably way out in the ozone - will be affected. If a problem, that would show up in the picture immediately. If for noise suppression from the outside, only certain places would have such interference happening on the outside to begin with. If used in a timing circuit, any anomalies will show up very quickly during operation.

Not sure what that circuit does so I don't know what that cap does so I may be all wet, but I'll watch for any problems.

b

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

What I also know is that if it is capable of taking down the entire 15v power supply, chances are it is paralleled across that 15v supply line and has simply shorted, causing that power rail to go down to 0 volts. As such that would make it a filter cap.

Chances are that's not the only filter cap on the 15v supply rail, and since there are 2 of them - one on the MC301 and one on the MC201 - even tho these are identical boards, they are separate boards in separate areas of the PS board - then they are probably only for local filtering of those 2 particular boards. In addition to the more central filtering designed into that voltage rail.

As such I am simply going to be trusting the other filtering on that line instead.

b

[Terryfictv]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

- even tho these are identical boards,

b

The IC circuit and cap in question are "identical",however
the entire board is not identical and has a different P/N !
Just FYI.....

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

So each of those 2 little boards is not identical to the other? They looked ID to me.

There's not an awful lot of board area to survey there, each is like 1"x1". Since it would take a while to differentiate the differences, and since the IC and cap are the same, and since eyeballing it makes it look over 90% ID to me, I am guessing they are actually the same board with different part numbers. The part locator numbers would always be different in any case.

I would be surprised if the actual part number on each is not the same. In other electronics I see that all the time - same actual part number for 2 different board locator numbers.

b

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

In any case the boards are similar enough, with enough of the same critical components on each one, that I am willing to bet they do a very similar thing in the circuit; that they both accomplish the same task, each.

The set was just put into the bedroom, replacing another one, an LCD with screenburn, and at this writing this plasma has not shown any abnormalities.

Shorting out the +15v line like that cap was doing when in there is bound to be less healthy - and potentially more dangerous, which is what protection circuitry is all about - than allowing that line to be fully up at its +15.85v, like it is now. The bad cap on the MC201 was taking the +15v down, and throwing the set into protection where it would not turn on. Thus preventing overheating and any fire hazard.

No longer. No protection being triggered anymore. I feel safe not replacing that cap but just leaving it outa there, but will be watching for any abnormalities anyway.

b

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

I have the Panasonic TH-50PZ80U with the 2 blink error. I believe the repair is likely the same as listed here. I have attempted to replace the capacitor on the MC 201 but as my soldering skills are somewhat newly obtained I believe I may have ruined the board. It resembles a charred mess as I can't see both posts any longer. I will post a picture of the board and hopefully someone can advise next steps. If its done-for, please advise how to find a replacement MC 201 as I can't seem to find one or am looking by the wrong numbers. I am able to reseat the P25 connector (prior to my seelf made issue) and the tv would power on and work fine until I power cycled it again.

This is another reason I have elected to not replace those caps. This is mirco-electronics here, and not everybody has those soldering chops. We are talking about an SMD cap that is at most 1/16" LONG. Forget about wide! Wide is less than half that. It's super tiny, and so are the pads it is soldered to. SMD work is rife with peril when it comes to possibly tearing up runs and pads on what you're working on.

To remove the cap is challenging too, because you can't desolder one side enough to have it release without the other side being already loose too. If you try to pull it off the board while the other side is still soldered in, nothing will give, and as AWTVs found, the risk of tearing up that super tiny pad and run is substantial.

What I did was use my soldering iron to hit both sides of the cap in unison, releasing both sides at the same time. Then just swept it off the board, all of this taking very little time so it would not overheat anything. That way those pads had no chance of being traumatized.

Then I left well enough alone. Adding back a replacement cap exacerbates the risk of gouging out, shorting or in some other way compromising those pads and the runs they go to. Anytime you use regular wire, like the kind on a cap, on the delicate runs and pads of SMD boards, the risks escalate, as the wire is huge compared to the super tiny run involved. Pulling that run off the board is all too easy once a comparatively big thick wire has been soldered to it where tugging on it is all too easy. In one of the pictures we see the long wires of the replacement cap going from the cap to the board. One false move - in this case moving the small board which is only held in by the wires soldering it to the big PS board and is thus effectively floating in space - or even just accidentally bumping it, and you'd pull those pads and runs off the little board.

Just leaving it alone after the bad cap has been removed is safest, IMHO, esp. when the owner is not highly experienced and thus qualified to do high precision work on super small devices.


I also did the removal without ever uprooting any of the boards in question. Just left all that alone and simply removed the cap while it was on the small board while that board was still on the PS board. The more you leave alone in electronics, the better. Something can always go wrong, and lessening your chances of that happening is one of the secrets of staying in business when it's repairing things like this. I have seen $6000 Pioneer Elite CRT HD sets massacred by doing all this troubleshooting that was not necessary and causing solder bridges because of resoldering a board that never needed it. There are many ways of screwing up in this business, and I can certify that I have inadvertently discovered many of them, much to my chagrin.

I now leave well enough alone as much as possible. Limiting your scope as to what you become invasive with in electronics repair and troubleshooting is paramount for me these days.

b

[ZnsaneRyder]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

Thanks folks!

I just repaired one of these TV sets with the same 1uf failed MLCC.

I replaced both caps with a 63V, 1uf Mylar Capacitor. It's not a surface mount part, but I just soldered the legs of the Mylar cap to the SMD pads for the old cap.

Works great. I chose that kind of cap because of they usually have very high reliability and performance.

Measured better than my 1uf electrolytic caps.

I will now be on the lookout for these Televisions!

[timbal]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

buenas tardes amigos.. soy nuevo poraqui... tengo un panasonic de plasma modelo TC-P46C2 con el problema de dos parpadeos despues de chequear visual mente el tv y medir tenciones segun el diagrama de la tarjeta estan todos los votajes y el tv no me prende.. tambien despues de sacar la tarjeta main me di de cuenta q ahora el bonbillito se queda fijo y no parpadea.. se activa el relec pero no hace mas nada luego le doy apagar y se desativa el relec... le agradesco a quien me pueda alludar ya q mi esperiencia en plasma y lcd no es muy buena... de ante mano gracias

[vinceroger69]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

buenas tardes amigos.. soy nuevo poraqui... tengo un panasonic de plasma modelo TC-P46C2 con el problema de dos parpadeos despues de chequear visual mente el tv y medir tenciones segun el diagrama de la tarjeta estan todos los votajes y el tv no me prende.. tambien despues de sacar la tarjeta main me di de cuenta q ahora el bonbillito se queda fijo y no parpadea.. se activa el relec pero no hace mas nada luego le doy apagar y se desativa el relec... le agradesco a quien me pueda alludar ya q mi esperiencia en plasma y lcd no es muy buena... de ante mano gracias

can you re post this in english thanks.

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

It has now been a year since I performed this repair by removing the caps and not replacing them - see my posts here above from a year ago - and my set has been performing flawlessly ever since. We watch it all the time, and often my gf has it on all day during the summer here since she is a teacher. At which times we of course keep the contrast level super low to protect the phosphors. Then we crank it back up for prime time.

I would say that that confirms that simply removing the cap(s) in question will have no unintended negative consequences. The field research has been done, my set was the guinea pig, and the results are in. No problems.


Just reporting in. What you choose to do with your set is up to you, but as a professional electronics troubleshooter and repair person who mans a bench in Redwood City, CA 3 days a week servicing very high end audio and video units like McIntosh, Carver and Runco - and has his own personal freelance business aside from that, which I also do - I recommend the simple removal of the caps and stopping there. Rather than going in there again to install the replacements and taking yet another chance on something unexpected happening - first one unavoidable, the second one totally avoidable - possibly caused by something as simple as missing something on inspection. Like a solder bridge or a pulled up or broken run. Who knows what will happen then? No way of knowing. Sets are not factory tested for things like that, so there's no road map. It could cause a very bad instantaneous chain reaction, you set could be toast in an instant.

I didn't coin this, but I live by it: Keep it simple, s*****.

Worked for me.

Mr Bob

[Terryfictv]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

I agree with Mr Bob ! Soldering small circuitry that requires magnification is a
minefield of possible very difficult situations . So, the course of wisdom is to achieve the best result from the least correction that solves the problem ! Less intrusion is safer !

FYI..the little sister boards are not the same ( identical ) so not interchangeable !

MC201 = MDPPNB331

MC301 = MDPPNB102

( Look on the reverse side of IC )

You will see noticeably different SMD parts !

[morglums]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

I was having a 2 blink/10 blink error on my 46 inch plasma (TH-C46FD18). I did Bob's fix and just removed the two tiny caps on the MC2/3 boards and got the set to power on. It wasn't too difficult with a small tip solder iron and a pair of tweezers.

We will see how it goes.

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

I agree with Mr Bob ! Soldering small circuitry that requires magnification is a
minefield of possible very difficult situations . So, the course of wisdom is to achieve the best result from the least correction that solves the problem ! Less intrusion is safer !

FYI..the little sister boards are not the same ( identical ) so not interchangeable !

MC201 = MDPPNB331

MC301 = MDPPNB102

( Look on the reverse side of IC )

You will see noticeably different SMD parts !

That's right. I checked it out and tho they look similar, they are definitely different. Nice catch, Terry!

[richij]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

Thanks so much to everyone for their contributions. Yesterday, I snipped out the two tiny caps. Now my 9-year-old 50PZ80B is back to its old self.

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

It has been nearly 3 years now since I took the caps out and left it be, she's been entertaining us ever since, nary a gliche anywhere. Not going further is definitely the key.

I would not just "snip them out" tho, as they are SMDs and you could snip something you didn't intend to, or even pull up a trace on the board. I'd desolder them out with tweezers or a dental pick. And VERY carefully, lest you bother anything surrounding them.

Remove them, DON'T replace them, wrap it up again and don't look back.


Mr Bob

[electro-raf]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

this is the same sort of fault I use to get with the Pace ntl receivers back 10 - 12 years ago
basicly its not the cap that goes bad its the damn glue they use during the soldering stage when making the boards. I actually took mine out and they measured good but cleaned the board and then replaced with the ceramic ones i took from another pan power supply and nice bit of soldering and bingo - apparantly the glue tracks a small resistance when moist as it goes crisp with age. also these pans give problems when fans and vents are totaly blocked.

[mrbob84]

Re: Panasonic Plasma TH-50PZ800U power supply light 2 blinks

I think you meant to say "panels" in that last line? Pans doesn't really get the point across, at least to me. Unless you use that word so much you needed a shorthand for it! Granted, you might have a point there...

Yes we have been seeing problems with that infernal glue they used in there, for decades on all sorts of electronics esp. amps. The older it is, the more chance there is that it is causing problems. Just gotta be careful when removing it to not sever a tiny run that might be under it.

I am again going to caution newbies against replacing that defective cap. Just remove it, and very carefully. Soldering bits of carbon that small is challenging even for me, a seasoned pro, which is why I elected not to. Please read my earlier posts about this, above.

Electro-raf, my hat is off to you. Good soldering.

Mr Bob