Help with WG K7191 ???

[D_Zoot]

Heya guys and gals,

Went over to look at a friends WG 25K7191 tonight for no picture.

He's already done some caps, the flyback and the horz out transistor
to try and fix it with no luck (he's been throwing parts at it). He
also resoldered pretty much everything.

I took a quick look at it and made the following notes:

No blown fuses.

Ok looking signals at R, G and B on neckboard.

 B+ is high at 153v,  but lifting D10 to kill the shutdown circuit
doesn't bring the picture up..  Besides,  HV sounds like it's working,
get static crackling from screen on power up.
Figuring I had a Horizontal deflection problem I did a quick scope
check at the HOT base and it shows what looks like a decent waveform
so Q10 appears ok and the HOT and flyback are already new.

Looks like I have a regulator problem,  but with D10 lifted, I should
be getting a picture if all else is ok, right ?

Thats as far as I got before I had to go.  I'll be heading back this
weekend and was hoping for some ideas to take with me.  Any thoughts ?

TIA!
D

[D_Zoot]

Never mind !!!

Figured it out,  he had the thing utterly hosed from fooling around with it too much !!

After fixing his "fixes" I got the picture back but now it goes into HV shutdown, (which I suspect might have been his original problem)  looks like the regulator IC is bad.


D

[Ken Layton]

The B+ regulator is a frequent failure item.