Re: yoke resonant frequency

>I think we DO have common goals; to have a reliable display, but I don't think
>it is practical or necessary to design a complete replacement monitor if there
>is a replacement PC board for the deflection and HV PCBs. One thing I don't
>have any real data on is how reliable the HV transformers in the designs other
>than the Ampliphone are. Are most WG failures deflection and spot killer
>related?

I've fixed about 20 WG color vector monitors for myself, TravisH, ChrisH,
and TonyJ, so these are my somewhat unscientific findings:

HV Failures:
------------
1 blown flyback (Took out the BU209, BU406, and lots of other stuff with it.)

numerous Zener diode failures in the HV cage (ZD900, 901, and 902)

numerous burned up resistors (usually due to diodes/transistors shorting)

numerous small signal transistor failures (MPSA06's usually)

numerous dried out caps

(No 555, T901, BU207 or BU406 failures other than noted above)

Neck boards:
------------
No failures

Deflection board failures:
--------------------------
numerous low voltage power supply failures. Usually due to ZD100 and ZD101
shorting out

numerous resistor failures (R100-R103, always related to a diode of trans
going out)

numerous transistor failures (almost exclusively Q100 or Q101)

one deflection output transistor failure (2N3716)

A few MPSU57 and MPSU07 failures

In my experience, the VAST amount of problems have been with the power
supply section of the deflection boards. I've actually experienced very
few failures related to the deflection stages themselves. It should be
noted that I've only worked on about 10 full chassis with the 3716's and
3792's attached, the rest were just deflection boards and HV cages.

In the HV section it looks like the diodes go out or resistors break down
most often. Relatively un-eventful otherwise.

-Clay

Clayton N. Cowgill Engineering Manager
_______________________________________________________________________
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Received on Wed Sep 3 11:51:01 1997