whole new repair / learning world... plasma! Yikes!

[freakaftr8]

Re: whole new repair / learning world... plasma! Yikes!

your looking at the Brown and white connector. Sorry. Probe one lead of your voltmeter to white and the other to brown. You should get about 200 Dcv or so.

[freakaftr8]

Re: whole new repair / learning world... plasma! Yikes!

I guarantee you that SC board is littered with shorted mosfets. When you get to scoping this board you will want to use black lead to the soldered big leg and red lead to each end of all the mosfets on this board that start with the letter Q.

[freakaftr8]

Re: whole new repair / learning world... plasma! Yikes!

OK... I think I understand, you are checking the power supply line side of the disconnected cable... hoping that the power supply will at least provide some powering there before any shut down. Right?

That is correct. However I pretty sure that your power supplies fine. These things are very Hardy

This task will also tell is your SS board is good

[freakaftr8]

Re: whole new repair / learning world... plasma! Yikes!

Good God look it that SC board. There's Nothing worse than having all active components soldered directly to the PCB

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

wow 200v dc could be deadly... be steady my hand... :-)
Question: will the voltage remain there for a period (til power off) or will the system try shut down immediately based on not seeing some connection somewhere (ie. sc disconnected)?

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

Good God look it that SC board. There's Nothing worse than having all active components soldered directly to the PCB

me too, since I might have to try to removed them with a heat gun as posted that was linked here a bit back... :-(

nice heat sinking... :-)

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

I guarantee you that SC board is littered with shorted mosfets. When you get to scoping this board you will want to use black lead to the soldered big leg and red lead to each end of all the mosfets on this board that start with the letter Q.

OK thanks... I was doing it wrong. I did check the resistors mentioned in the kit and they seem ok.

[tvtimmy]

Re: whole new repair / learning world... plasma! Yikes!

Check these IBGTs for shorts: Q401,Q403, Q422, Q423,Q660,Q661,and Q600.
Watch this video. Tnpa5335 repair kit on youtube.
I use a 45 watt solder station and I dont have any problems. You have to check your parts that you buy to make sure they are not fakes from china.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

can someone explain how to do this check as mentioned in the first thread link that I posted...
"you try in continuity / diodetest on the buffers and run the probe slowly along the contacts at the panel ribbon connectors with respect to Vf gnd which is the plates that the bolts go in on the SD/SU. I would go slow if it's a cheap meter as response will be slow and watch for short cct. ".

[tvtimmy]

Re: whole new repair / learning world... plasma! Yikes!

Brown and white. There is a video you should watch on youtube: TNPA5335 repair kit.
Check your new parts before installing because there are sooooooooooo many fakes from China on the market.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

OK... I did a "diode check" on the suspected semis (Q402,403,422,423 and D401,402).
All are shorted. Check all other "equivalent" components on the board... all checked good.

So the question now is, what caused them to go out... subtending board is bad or the panel is bad? I checked the mounting screws, they were tight.

I kind of remember there are some "dependencies" where by if you fix one board but the subtending one is bad, it will take the fixed board out again. What further checks do I need to do

OK... I found further testing in the pdf.

[martino]

Re: whole new repair / learning world... plasma! Yikes!

OK... I did a "diode check" on the suspected semis (Q402,403,422,423 and D401,402).
All are shorted. Check all other "equivalent" components on the board... all checked good.

So the question now is, what caused them to go out... subtending board is bad or the panel is bad? I checked the mounting screws, they were tight.

I kind of remember there are some "dependencies" where by if you fix one board but the subtending one is bad, it will take the fixed board out again. What further checks do I need to do

OK... I found further testing in the pdf.

Check the board where the screws sit,you will see a darkened area on the tin,either front side or backside where it has been arcing.
They really are not too bad to repair,less scary as it seems. Any of our members close to you that can perhaps help? I'm willing to do it for cost,but I'm in Alberta

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

thanks.... i am probably just over thinking / cautious.... nothing to lose since it will just go back in the dumpster if i am unsuccessful where it was anyway ... :-)

it appears it will be less than $50 to get to a point one way or the other.... the budget should work.

[Wellington1]

Re: whole new repair / learning world... plasma! Yikes!

Not to interfere with this thread but as I saw a 50" Panasonic plasma locally for 30 obo ( TC P50VT25 - June 2010 ) that has mostly thin black vertical lines across the screen, described by the Seller, no images of it and I have yet to look personally but my understanding is that the panel is most likely no good?


It does function so all the boards are good - worth it for parts ( doubt I could use any them for my late 2012 U50 ) perhaps?

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

no problem.... if you look at the thread that i posted as my ref start, the guy had lines after his work.... reseating some cables cleared them up....:-) you might get lucky.

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

following the resistance test in the troubleshooting pdf, looking at the TPSC1 (R515) and VF-5V (pin 3 of IC724), both show good. I take this that perhaps only the SC board has issues as already identified... assuming that the panel itself is good (no visible signs of physical damage).

[freakaftr8]

Re: whole new repair / learning world... plasma! Yikes!

I've found in my experience that when a Panasonic SC board eats it's lunch, very rarely do I see failed SU or SD. I mean it can happen, but in your case sounds like you found them ok.

For removal of FETs soldered to the board, I use a soldering iron and lift both small legs. Then I break out the Weller soldering gun and tin the big tab, heat the hell out of it and use tweezers to pull up after I notice the solder underneath bubbling.

Once removed I use the Weller and run it over the pad to reflow the solder flat. Installation is usually the same but use flux and a little solder between the gun and top of tab. Use the soldering iron to solder down the 2 tabs.

It takes a minute cause of heat dissipation but they will come off. It's kinda like the dentistry of electronics repair..


Others may have a different view of how to do thjs, but it's never failed me yet out of the 200 or so FETs I've replaced..

[martino]

Re: whole new repair / learning world... plasma! Yikes!

It's such a common fault on that model that I don't even test buffer boards for it,leaving them on the ribbons as to not having to readjust them (can be a real pain on panny's).
I do replace all the parts in the kit as to be sure your work is covered,reality will show after removal that not all parts are blown as per kit. The surviving parts did get a good stress before failure so could be weak.
All points where screws meet the board should be reflown with fresh solder (both sides of board) to ensure the new screws make good contact to prevent a repeat of this fault.
They are nice tv's with a very decent picture,well worth the repair cost and adventure.

[freakaftr8]

Re: whole new repair / learning world... plasma! Yikes!

Indeed. You should see the SC board for a TC-50UT50 I just repaired for someone locally. Damn floating grounds! All the screw locations were blown and had to create new pads.

A word of advice do not remove buffer boards you can slide the SC board out from underneath the buffer boards just remove the screws.

Also why are in their tighten down the screws on the SS, SU and SD boards. They're gonna be loose. Preventative maintenance...

[budwich]

Re: whole new repair / learning world... plasma! Yikes!

thanks.... I am going to see if I can get the components locally as I only have a small window because of other things going on at home. Otherwise it will have to wait for a while.

PS. Freakaftr8, glad you got your oled working.... :-) that was a good trip!