Bizarre Amplifone Problem

Hey all,

        Here's a real stumper (or maybe not...)

        The background: I have a good Amplifone Deflection board, a
good Amplifone HV board (both tested by me, in my Quantum Cabinet,) an
untested Amplifone tube, and a Star Wars cabinet that has a perfectly
good and working W.G. monitor in it (i.e. the Star Wars game is 100%
working)

        I'm sure you see where this is going. I put the tube into the
Star Wars, hook the good boards up to it, and no workee.

        I get a picture, and the vectors are razor sharp and beautiful,
but they don't even come close to lining up. The "Star Wars" is just a
jumble of blue vectors, and you can tell that there is supposed to be
text after it, but all of the characters are unrecognizable. Basically,
all of the vectors are royally screwed up.

        I checked the connections at the harness, and they were OK.
Since this seems like a serious deflection problem, I checked the
voltages across the deflection coils -- I got 24 VAC across one of them
(the one that uses the brown and blue wires from the def. board) and
12 VAC across the other (the one that uses the yellow and red wires.) I
don't have the schematic in front of me, so I don't know which is which.

        Just to make sure nothing blew out when I hooked it up to the
new tube, I took the whole mess (both boards) back to my Quantum and it
fired up just fine (with good vectors.)

        Is there any defect with the tube that could cause it to display
wierd vectors like that? I would think not (maybe a defect with the
yoke?) but I've checked and checked and checked the connections and the
boards, and I really can't figure out what's up.

Any help would be much appreciated. This one's got me really scratching
my head....

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 Mon Oct 20 20:19:23 1997