Tempest repair question

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

I have a tempest pcb that I am repairing and am unsure what to be
focusing on.

The board is dead with the spot killer on and the player lights are on
solid. When I first powered up the board, it played blind, but then
failed to how it is now, dead.

There is no x or y output, the ROMS verify correctly, voltages appear
to be good, and the watchdog gives a steady 5V. What should I be
checking to get the CPU going again? RAM?

Dan

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

> What should I be checking to get the CPU going again? RAM?

What happens when you put the game in self-test mode?

Alex
----
ayeckley@elektronforge.com
www.elektronforge.com

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

There is no difference. It still has the watchdog at 5V, spot killer,
voltages look good, no beeps?

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

A bit more info. Checked the crystal and it is pulsing correctly and
so are pins 37 and 39 on the CPU.

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

lol, unfortunately I spend alot of time on option 5...

Thanks for the tip.

Dan

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

> There is no difference. It still has the watchdog at 5V, spot killer,
> voltages look good, no beeps?

Here's my guesses (just guesses, since we can't test it first-hand), in order of likelihood. If you'd like to send it out for
repair, our shop is one possibility:

1. CPU (and/or CPU socket)
2. Scratchpad RAM(s)
3. DVG/VSM - that's where it gets fun
4. EPROM sockets (since you mentioned that you've already checksummed the EPROMS themselves)

Good luck...

Alex
----
ayeckley@elektronforge.com
www.elektronforge.com

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

> Here's my guesses (just guesses, since we can't test it first-hand), in order of likelihood. If you'd like to send it out for
> repair, our shop is one possibility:
>
> 1. CPU (and/or CPU socket)
> 2. Scratchpad RAM(s)
> 3. DVG/VSM - that's where it gets fun
> 4. EPROM sockets (since you mentioned that you've already checksummed the EPROMS themselves)

Wait a second - forgot the most important one:

5. Other

Alex
----
ayeckley@elektronforge.com
www.elektronforge.com