Re: Hmm.... mo StarCastle problems...

> My Space Wars had the same symptom. Something around the 7406 on the
> monitor board was buggered up. I never did find it, but when I lifted
> the pin on one of the 7406 inputs the problem went away. (I think their
> equivalent of a "spot killer" was turned on for some reason. Seems like
> it monitored the voltage supplies.)

Had same problem on the one I'm working on (Ray's).... Turned out to
be a shorted tantalum cap.

Symptoms:

You can hear the X and Y drivers on the deflection yoke.
No high freq whine and no high voltage.
No picture on tube at all (obviously, with no HV).
Blows the 0.5A fuse on the power supply (I didn't notice this at
first).

If the 0.5A fuse blows, you *know* you have a spot killer problem.
That's the only thing the line from the PS feeds (unless I missed something).

I turned to brute force of checking each component along the spot killer
circuit (aren't that many). The shorted cap had no external signs of
problems (even though one near it had literally blown the top off).
(Note: I'm talking about the 2.2uf tantalums they use around all the
voltage regulators...)

Until I noticed the blown fuse, I was totally barking up the wrong tree
(testing the flyback, changing the transistor that drives the flyback,
checking diodes coming off the flyback...).

Just my $0.02...

--- Cris

 -----------------------------------------------------------
 Cristopher J. Rhea Mayo Foundation
 Research Computing Facility Guggenheim 1001B
 crhea@Mayo.EDU Rochester, MN 55905
 Fax: (507) 266-4486 (507) 284-0587
 -----------------------------------------------------------
Received on Wed Mar 25 11:14:37 1998