Help Please repairing a TV - just light level

Thread Starter

boydage

Joined Oct 7, 2016
87
Im an electrician with basic electronics experience. My Panasonic Viera smart TV has just gone black screen. And wont reset via "power-off"

I have a lot of experience with stuff that hey, just has a failed power supply. So I think, before I throw this in the bin on its way to the hole in the ground. I have a crack at getting it to run again.

I am actually quite annoyed. Its like 6 years old. Is that how the world goes now we manufacture so much stuff that craps out way to soon. And the world is filling up with this rubbish.......

Anyways. Back to me. Can someone please just point me into a few directions with my meter perhaps I can get this going again. Regards
 

dendad

Joined Feb 20, 2016
4,140
The first thing to look at is the electrolytic caps in the power supply. That is the most common fault. The caps drying out can also cause spikey power to pop other things, so just replacing the caps may not be all that is needed, but it is a good start.
Use low ESR capacitors as usually they carry quite a bit of ripple current. And go with 105degree versions, not the lower spec 85degree types.
Do you have a capacitance meter?
 

Thread Starter

boydage

Joined Oct 7, 2016
87
Oh. Sorry. I need to clarify - that most items I have worked on in the past have a power supply issue.

This particular piece of equipment I dont know where to start. Although the power supply will be first look I guess correct?
 
My Mother in law has a Panasonic from way back when and it goes out about once a year. I literally remove the back panel and unplug the boards from each other and plug them back in and Presto!. I've done it about 5 times...
 

bassbindevil

Joined Jan 23, 2014
422
See if you can find the service manual online. That should have voltages to check. And google the model and/or chassis number and you may find that other people have had the same problem. Otherwise, I'd check for bad caps. That usually means caps that have bulged at the top, and leaked a bit of brown electrolyte at the "x". The failed caps I've replaced haven't leaked as much as those in the picture below, but based on measurements on caps that were in various stages of failure (from bulging but intact to burst), any amount of electrolyte leakage means the capacitance drops to near zero.
https://en.wikipedia.org/wiki/Capacitor_plague#/media/File:Al-Elko-bad-caps-Wiki-07-02-17.jpg
 
Last edited:
Top