TX-W28R3DP - popping noise any help ?

[ceeghb]

First post guys.
I've read all the Panasonic post but found similar post to this but not for my model and no resolution.
My Panasonic W28R3DP has started popping it speakers.
It's like a HV or static crack- the sound usually dies for a second then comes on again.
I'm at my wits end....
This always happens within the first 10 mins of switch on from cold, but has happened when the sets been on for hours and is warm.

I think it's affecting all speakers but at least the centre one. It also affects line out as I've an sub which obviously exagerates the problem ! Thump !
Just hoped someone had come across this before ?
Things I've done already.
1) Checked for obvious failures.
2) Checked for dry joints
3) Checked the HV anode is not arcing to tube.
4) Check over sound sub pcb for obvious failures
5) Ran the set in the dark to see if I can see any arcing - non seen :-(

Has anyone experience this before ?
I'm begging to wonder if it's a HV cap or a electrolytic drying ?
Any pointers much appreciated.
Set is around 7 years old
Thanks

 

[rayferry]

Resolder 12V regulator IC7502, dry joints on this component causes the sound to come and go.

 

[ceeghb]

rayferry, thanks for replying. Can you tell me if this is on the main board or the sound sub board?
Thanks

 

[rayferry]

Sorry I can't remember no service manual at hand, but I found this,
no 12V on K board, DJ on IC7502 12V regulator. I think this set is the EURO3W chassis
Sorry I cannot be anymore help

 

[ceeghb]

OK, thanks anyway I'll have a hunt around....

 

[ceeghb]

I had a look last night but couldn't find an IC7502 most of my IC's finish at 3800 or so. Could find and obvious 12V regulator either.
Oh well back to square one !
Any others help please ?

 

[rayferry]

I found a service manual sorry but I got the IC numbers wrong here are the correct ones.
IC2502 12V regulator
IC2503 5V regulator
IC2508 9V regulator
IC2502 is the one the gives the most trouble but it would not do any harm to solder the joints on the other ones too.

 

[ceeghb]

I found a service manual sorry but I got the IC numbers wrong here are the correct ones.
IC2502 12V regulator
IC2503 5V regulator
IC2508 9V regulator
IC2502 is the one the gives the most trouble but it would not do any harm to solder the joints on the other ones too.

Had a look at these last night, but they were all ok and giving the right voltages out, apart from the 9V which was a bit low 8.8V...?

 

[Hogarth]

cant help you fix it but I have the same problem with the same model, a loud pop (or bang), like a static discharge, killing sound to all speakers for a second or two - slowly getting worse and now also getting a background hum as well.

I am not technically capable of doing any repairs myself but would be keen to know if those of you who are might comment about economic viability of a commercial repair?

 

[ceeghb]

Couldn't find the fix for this. In the end I disconnected all speakers and bought a surround sound amp (which I was going to do anyway...)
Coz it's happened to you to, this *must* be a common fault but maybe no-one that fixes panasonics read this ?

Hard to say if it's economic to fix this, not knowing what's wrong with it...
Was/is a great TV though!

Hope you find an answer....