Re: B/W XY help

Joe,

Make sure you have a glowing filament. I've had several BW vector
monitor failures that were simply due to cracked solder joints on the
deflection board that connect the AC to the filament.

If the filament is glowing, spot killer not lit, and you hear deflection
sounds, then check to see if you actually have HV since that's more
likely the problem than the Z amp transistor having failed. That is, if
after running the monitor for a moment, you unplug it, and "discharge"
the tube, do you get a spark as if you were really discharging the tube,
or is it quiet (no HV)? Of course, having a probe with a KV meter is
the best way to know for sure, though the noise test is usually
adequate.

The Hv board on this monitor is pretty sparsely populated. It shouldn't
take you too long to test each piece of silicon on there if it comes to
that. These HV transformers on the BW monitors are fairly robust, so
I'd not guess that's the problem, yet.

Good luck,
Joel-

jwelser@ccwf.cc.utexas.edu wrote:
>
> Hey all,
>
> I'm trying to repair my first B/W XY monitor (it's a WG 19V2000,
> from my Battlezone,) and have some questions...
>
> Symptoms: No picture. Spot Killer isn't lit. I hear clatter in
> the neck. I already tried replacing the HV diode, and that didn't do it.
> The 40V input to the HV unit is in the neighborhood (it's actually a
> little low, but it's in the mid to high 30s so I'm guessing that it's OK)
> of where it should be. I already checked a bunch of the transistors on
> the HV unit, especially the outside mounted ones, and they're OK.
>
> I still get no picture, though. My next step was going to be to
> check the Z-amp transistor (Q504, I think it is) but I wanted to see what
> you guys thought it might be....
>
> Thanks,
>
> Joe
>
> ------------------------------------------------------------------
> Joseph J. Welser jwelser@ccwf.cc.utexas.edu
> Design Engineer -- Crystal Semiconductor Corporation
> Ph.D. Student in E.E. -- University of Texas at Austin
> Work: jwelser_at_crystal.cirrus.com http://www.crystal.com
> P.O. Box 17847; Austin, TX 78760
> ------------------------------------------------------------------
Received on Wed Oct 8 11:56:21 1997