Re: No Replies to Tempest tech question?

On Tue, 31 Aug 1999, Al Warner wrote:

> I can't believe that I didn't get ANY responses my Tempest board
> questions. Could anyone give me ANY information? I really would
> appreciate it.

Al,

        It's possible to troubleshoot the aux board using signature
analysis. The procedure is given in the Tempest troubleshooting guide.
This is probably the best way to go for messing with aux. board problems.
It pre-supposes that you have a working main board.

        Now, on to your specific questions....

> The program seems to be running, but I seem to be having problems in the
> ALU / Pokey area of the Aux board.

        Why do you think this?

> Reason: Vectors jumbled on game grid and during much of the attract
> mode. Sounds are random or just a bunch of noise. Controllers mostly
> dead. Sometimes the buttons work (1/2 players, SuperZapper). Enemies
> and player cursor look OK.
>
> Question 1: Should rearranging the ALU chips produce different problems
> on the screen or is it all one big matrix and that won't make a
> difference? I tried cleaning / moving the chips around, but the results
> are the same.

        Maybe. They are but it looks like you answered your own question.
Those are bit-slice microprocessors (The AM2901s.) I'd think swapping
them would cause different bits to be bad, thus causing different
problems. If in doubt, why not just replace the parts with spankin' new
AM2901s?
 
> Question 2: Is there a chip / component that controls both Pokeys and
> ALU?

        Not sure. You should be able to see this on the schematic.
 
> Question 3: Has anyone seen these symptoms before?

        No, at least I haven't. Does the self-test tell you anything
useful, or does it pass?

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 Tue Aug 31 12:12:53 1999