Re: yoke resonant frequency

At 11:04 AM 9/3/97 -0700, you wrote:
>
>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?
>

Actually the "spot kill" circuit in the P314 (WG61) does not usually fail,
rather it kicks in when the output of the VG fails. The main failure point
for the P314 is the deflection amps, and the low voltage power supply. The
low voltage supply is easily fixed by using a regulated supply design that
has thermal and current protection. I actually have a redesigned LV supply
in my Tempest's 6100 monitor, and it has been working great for about 6
months!
The deflection amps fail partly because they are supplied by a poorly
design LV supply, and partly because the "power" BJTs get hit to hard by
the inductive kick from the deflection coils...and eventually burn out. Al
mentioned the LT1166 driver...got me thinking, so I looked at the data
sheet, and this could be a very solid solution, designing an "audio" type
power amp with it -- i.e., staying with the Class AB type push pull design
that is currently there. It looks like this would require quite a few
support components to get the job done -- several op amps for gain control
and pre-output stage buffering to get very low distortion.
I think it is a solution worth considering, but...
I think we need to get a couple of solutions on the table, have a "design
review" with those who can provide solid input -- then prototype a couple
or three and see which gets the job done, most elegantly, robust, easily
reproduced (parts availability), and price...

-Anders
Received on Wed Sep 3 11:49:41 1997