Sanyo DS25380 Vertical Problem

[Rob]

I have replaced the LA7841 vertical output ic and got the unit back up
and going again, but the ic is getting too hot and vertical linearity is
not good. The top part of the picture is fine, but the very bottom is a
little compressed. Possibly yoke short? I did find some bad caps in
vertical section and it did correct some of the problems. Just wondering
if anyone has run into this before on this series of set?

 

[[email protected]]

Rob:
You probably missed a cap or two.... re-check your work. If you
suspect the yoke you should ring-test it.
electricitym

 

[Leonard Caillouet]

How do you ring test a vertical yoke? Every one that I have ever tested has
no more than 4 rings with either of 3 Sencore units that I have. I have
never found this to be an effective way of evaluating vertical yokes. How
do you do it?

If a yoke is working and the problem is linearity, the problem is almost
always going to be a bad cap.

Leonard

 

[[email protected]]

Leonard:
If you ring-test a yoke with a shorted turn and compare the results
with a good yoke you can see the difference immediately...... a yoke
with a shorted turn will have lower amplitude rings and be quite
obvious when compared to a good yoke. I always keep a good yoke handy
in my junk box for this reason.
electricitym
..
..

 

[Tom MacIntyre]

How do you ring test a vertical yoke? Every one that I have ever tested has
no more than 4 rings with either of 3 Sencore units that I have. I have
never found this to be an effective way of evaluating vertical yokes. How
do you do it?

If a yoke is working and the problem is linearity, the problem is almost
always going to be a bad cap.

Leonard

I think it's the vertical yoke that has a parallel resistor that has
to be taken out-of-circuit before an accurate ring test is possible.

Tom

 

[Rob]

How do you ring test a vertical yoke? Every one that I have ever tested has
no more than 4 rings with either of 3 Sencore units that I have. I have
never found this to be an effective way of evaluating vertical yokes. How
do you do it?

If a yoke is working and the problem is linearity, the problem is almost
always going to be a bad cap.

Leonard

Thanks for all the help on the vertical problem, I seem to be finding a
lot of dried up caps. I think where unit was located, it didn`t have
much ventilation and it had alot of dust. Rob