Tempest Troubles - Please Help

I finally tracked down the proper power supply for my tempest,
but the game still plays blind. I went to the Diagnosing Tempest
page (http://www.kfu.com/~nsayer/games/tempest.html) and walked
through the hyperlinks and this is what I came up with:

Start
 * No video, LED on monitor deflection PCB on, start button LEDs blink, game basically plays "blind"

Spot Killer
The spot killer has activated indicating either X or Y deflection is not
occuring properly. Take a scope or a voltmeter and look for +/- 6 volt swings
on the X and Y out loops on the main board.

* No, one or both are stuck (the actual reading was .3 on both, I think)

VSM Analog faults
One or both of the deflection outputs is stuck at this point. I will presume
it is the Y deflection that's not working. You will have to adapt a bit if X
is the problem.

Turn the brightness up on the monitor SLIGHTLY until you over-ride the spot
killer. Don't leave it like this very long! It is very bad for the tube to
not be deflecting the beam a lot. You should now see the screen "crunched"
into a flat line. Wiggle the Y centering pot. Does the line move up and down?

* No (Neither the X nor Y pots do anything.. just the dot in the center)

Check deflection output amp
It appears that the final output amp of the deflection section (D/E13) is
bad. Also check C13, the analog multiplier.

I replaced D/E13 and C13 for the Y axis and the same chips for the X axis,
but there was no change.

While I was poking around, I noticed that the +15v test point was only
reading 3 volts. Is the 15v used "for +/- 6 volt swings on the X and Y
out loops on the main board"? Where should I look at this point? All
other voltages are ok, and when I put my (what appears to be dead
although was supposedly working when I bought it) Major Havoc board in,
it does have the 15v. I guess what I'm saying is that the power supply
and ar2 seem to be ok. Any thoughts?

Jon
Received on Wed Mar 31 07:06:37 1999