Panasonic tv doesn't have picture

Do you have a question? Post it now! No Registration Necessary

Threaded View
Hi,
My tv has stopped working. The symptoms are as follows,

Recently I noticed that the picture requires ever longer times
to start after switching the tv on. The sound comes on
immediately. I new that eventually, the pictures will not come
on, and now I have reached that point. It seems as though
the picture cannot "complete" the "warm up" stage. The
screen is completely dark, i.e. as if there is no power.
I have checked all the controls, and it is not a brightness
setting or the tv/vcr switch, I am sure of that.

The model is Panasonic TX-W28R3

I am guessing that this is due to some dried out electrolyte,
but this is just my educated guess, due to the fact that the
fault became progressively worse, which could be an
electrolyte in the process of drying up.

If anyone has any experience with this particular model, please
tell me what is the part, and I will fix this in a flash.

Thanks
B.Eng


Re: Panasonic tv doesn't have picture

Quoted text here. Click to load it

It may be something to do with the CRT heater supply, which could indeed be
due to bad electrolytic caps, or bad solder joints, especially on the CRT
connector.

Quoted text here. Click to load it

I take it you are skilled in electronics and are aware of the potential
lethal dangers within a CRT TV? First things first- check the neck of the
CRT glows. If it does, the set will need some skilled diagnostics to get any
further. If it doesn't, the fault should be easy to find as there are few
parts to go wrong  in the heater supply on most sets. Usually it will be a
bad solder joint or broken PCB track.

Dave



Re: Panasonic tv doesn't have picture
Quoted text here. Click to load it

Dave,
I know about the dangers (I have a diploma in EE).
When you say it may be a bad solder/track, this does not explain
why the problem got progressively worse. A bad solder/track usually
causes an intermittant problem?



Quoted text here. Click to load it


Re: Panasonic tv doesn't have picture

Quoted text here. Click to load it

Yes but a CRT heater has a lot of 'thermal inertia' and takes a good few
seconds to go from off to on, on to off. A bad connection can often become a
good one once parts warm up and expansion sets in. With ageing, thermal
expansion and contraction and some arcing, a worsening connection can be
fully expected.

However, I agree the most likely cause is thermally sensitive components,
especially electrolytic capacitors.

Dave



Re: Panasonic tv doesn't have picture
Dave: Use your ESR Meter and check the associated electrolytic, having the
EE Diploma will definitely assist it the rest of the quandary. Cheers.
FWIW Panasonic and Sony have been known for multiple 'ring cracks' in their
soldering, esp after a few months of thermal changes during nominal
operations, it's probable a good illuminated inspection mag lens will
assist?
Quoted text here. Click to load it



Re: Panasonic tv doesn't have picture

Quoted text here. Click to load it

Thanks, but I'm not asking the question, 'info' is the OP!

Dave



Site Timeline