Tech: Please Help me with Quantum troubles

Hello,

     My Quantum has the following troubles, please help if you can.

     Game coins up and sounds fine. I get no ram or rom errors as indicated by
the 1player / 2 player led's. I am only getting a picture on the left half of
the screen, but the picture is garbled - looks like weak wavy lines streaming
from strong lines down the middle of the screen. This is not a deflection
problem. After troubleshooting 2 Amplifone deflection boards for 3 days, I
realized that after testing my Quantum board on my working WG monitor, I've
found that my problem is NOT deflection board related. (I got the same problem
on my WG monitor, and the WG works fine in my Gravitar cabinet.)
     The stray lines that seem to grow from the center look like trace lines
for the beam. The spot killer turns on after a short while, and will
occasionally turn off. When the spot killer is on, I get no picture (duhh!)
and when it goes out, I get the usual left screen garbage. I am getting all
colors (none are missing).
     I"m thinking I've got a AVG problem here, and I think it might be in the
Y section (since Quantum is a verticle game). I'm getting the following
readings from the board:

+5 is at 5.13v
-15 is at -16.32v
+15 is at 16.26v
+6.8 is at 7.27v

     I've tested my X and Y outputs, and they seem like good signals on the
meter set to AC. (I have no scope, so I've got to use the meter...)

x output varies from 2.70 to 3.75v AC
y output varies from 3.29 to 4.62v AC

     I'm really lost here, and don't know what to test next, and don't have
any idea of how to fix this problem. I was able to fix a problem a couple
weeks ago in the X output stage (I changed a TL82 after getting no x output
signal, this fixed the problem), but this one is alot tougher for me. Is my Y
output signal too strong, and is this casing the spot killer & input
protection to kick on? What could be wrong with the Y area of the AVG?? Is my
Y output signal normal?

Please help if you can, I'm really lost on this one.

Thanks Very Much,
Michael Kelley

   
Received on Tue Sep 29 00:28:52 1998