Re: Tempest debugging

Just an update on our Tempest restoration.

In an effort to make the system stable, we pulled each socketed chip,
cleaned it's pins, and re-inserted it. We also clean the pins on the
connectors for the interboard cable, cleaned the card edge connectors,
and used a needle to flex the edge connectors out to make better contact.

We re-assembled the machine, applied power, and the math box came up
completely broken. :-( No earom, no pokey, no math box, nothing.
A quick look showed the LED on the math box was not lit. We got out
the wiring harness diagrams, and discovered the true horror of power
distribution on Tempest. +5V comes from the audio/reg board, goes
to the logic board, comes out of the logic board on a different
pin on the same connector, and then goes to the math box. And the
contact on the math box edge connector where power went in was still
dirty, even after the prior cleaning. After some more cleaning with
an eraser, we tried again, and power came on, and it worked and stayed
working!

Still no sound though. Out comes the scope, and we trace the sound
signal through the wiring harness till we find a blown speaker. :-)
Finding a replacement was interesting, because there are sooo many
4 driver 6x9 speakers that supposedly can handle 200 watts for the
automotive market. All I want is a decent speaker that can reproduce
8-bit synthesized sound from a Pokey. For anyone else in a similar
situation, I finally found the Boss Audio BRS69, and found them for
$10 each here:

http://www.thenerds.net/BOSS_AUDIO_SYSTEMS.Boss_BRS69_Replacement_Speaker.BRS69.html

All we have left to do on Tempest is adjust all the pots on the game board
and possibly some on the monitor. Oh, and lubricate the spinner. It has
the dreaded spinner buzz. I wish Chumblespuzz was still making the
oil-impregnated brass bushings for Tempest spinners. But a friend has
loaned me his tube of the Atari recommended Nyogel 799 lubricant. That
seems to work rather well.

___
Ken

Ken Sumrall wrote:
> Now that my friend and I have a working WG6100 (I even installed the IPC
> board) it wsa time to put everything back together. We tested the
> power supplies, put the monitor in the cabinet, installed the game board,
> and fired the machine up. To our surprise, we saw the high score screen
> come up on the display. But none of the buttons worked, nor did the
> player start switches flash. I didn't notice at the time, the the attract
> mode didn't start either.
>
> So, we called it a day and Bill went home. As I was cleaning up, I
> realized
> that since none of the I/O worked, and the attract mode wsan't coming up,
> the math box was probably bad. I pulled the board set, pulled the big
> interboard connector off the math box, checked for anything obviously
> wrong,
> and re-assembled it and tested it.
>
> Viola! The buttons worked, the attract mode started, and I could play the
> game! Woot!
>
> No sound though. I'll dig into that later. Can't be too hard to figure
> out.
>
> The game did lock up once after about 5 minutes, but power cycling brought
> it back and it didn't lock up again.
>
> So, it looks like we're close to getting this machine restored. Besides
> the sound (which I'll debug with my portable o-scope next time) I'm
> wondering about how to ensure stability in the system.
>
> We already have:
>
> 1. Replaced all the electrolytics on the Audio/Reg board.
> 2. Replaced the big blue cap in the power brick.
> 3. Cleaned the card edge connectors with q-tips and alcohol.
>
> My concerns are:
>
> 1. The card edge connectors seem pretty loose, and I worry that they may
> not be making good contact. Is there any advice on what to do here, save
> replacing the connector? Bill suggested using a needle to bend the
> contacts
> in the connector further out to make better contact. He used to have to do
> that to his TRS-80, way back when.
>
> 2. What is the best way to ensure the interboard cable and connectors are
> making good contact?
>
> 3. I see the Real Bob Roberts has a cap-kit for Tempest. Is that worth
> doing? Working on a Tempest board is more delicate than the monitor
> boards,
> so I don't want to risk pulling up any traces unless people think it's
> worth
> installing the cap kit. I'm rather handy with a soldering iron, and have
> two Metcal irons with lots of tips, so I have the tools and skill, but it's
> still a risk.
>
> Thanks everyone! We're almost there!
>
> ___
> Ken
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Received on Sat Aug 13 03:51:48 2011