Re: No Replies to Tempest tech question?

I'm going to combine some responses and I really appreciate the help here!

Jess Askey wrote:

> Al Warner wrote:
> >
> > 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.
>
> Moving the chips should not result in any changes. If there are, you have a
> bad ALU.
>

So that means my ALUs are all good then because the problem is the same no matter
which order they are in.

>
> >
> > Question 2: Is there a chip / component that controls both Pokeys and
> > ALU?
>
> Yes. The CPU controls both of them. But that doesn't help much.
>

Yes, but thanks for answering.

>
> Take a look at the schems to see if the Pokey's and Mathbox go through
> a common buffer (LS244). Also, you may want to check the Self Test Screens
> to see if you have a mathbox problem.
>

I get the M so I know there are mathbox problems. Aren't the ALUs the first place
to look though?

>
> >
> > Question 3: Has anyone seen these symptoms before?
> >
> > Before you ask, Resoldered interboard connector pins (removed old
> > solder, replaced with new) on both boards.
>
> If your ALU's are have blackened pins you may want to clean them. Or if
> you have Tan colored sockets, replace them.
>

That was done. No change.

>
> Sounds like you have a bad connection somewhere. Does pressing on the boardset
> make matters worse?

This I will have to check when I get home tonight.

welser@ccwf.cc.utexas.edu wrote:

> 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.
>

Unfortunatly, I do not have access to the tools required. Just hoping to get
lucky and use some "good advice".

>
> 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?
>

Lack of controls, bizarre vectors on the screen, spot killer kicks in at regular
portions of the attract mode screen.

>
> > 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?
>

Local shops don't carry them, I will be purchasing some new ones.

>
> > 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.
>

I'll have to spend some more time with it.

>
> > 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?
>

Fails with the M. I thought I saw some other "Letter" appear, but I didn't see a
reference to a "F". I'll have to look again.

To all: Thanks very much for helping me with this. I understand that I don't know
a lot about this level of electronics. I appreciate what you guys are doing to
help.

-Al-
Received on Tue Aug 31 14:31:06 1999