Star Wars Yoke Problems - Anyone have any ideas where to go next?

[lsneighbors]

Well I have my Star Wars cabinet out of storage and finally decided to get it working.  The power supplied seemed to have fried a few things thus the reason for putting it in storage so many years ago.  I have had it in storage since 1988 and I have replaced a lot of stuff in it to get it where I have it now - everything working except I have no yoke controls.  Here is a list of what has been replaced:

1) entire power brick rebuilt
2) all Caps replaced on AR board along with the voltage mod being applied
3) rebuilt the entire yoke assembly with new gears, pots and wiring
4) replaced the following chips
   ADC0809       9K
   TMS55220NL 1C/D
   6532A           1E
   2 of the 8310 3D & 4D
   TMM2016AP   1F/H
   Both Eproms  1J/K & 1H
   6809             3K

The voltage lines on the ADC look good and change with the controller; however the signal lines look terrible on an OScope can't seem to get a clean sync or there are multiple signals running on top of each other.   I thought about just replacing all the chips starting with the 244's but thought I would throw it out there and see if anyone could possible have a hint where to look next before clipping out chips to replace.

Oh one other thing anyone know what the chips are at 7H, 7J, 7K and 7L  the schematic shows them as one thing but the part number on the chip shows them as something else.  The schematic shows it being a 1k PROM and the chip number shows it as a M3-7643-A which refers to some type of current generator which I don't think is correct.  The only reason I ask about these guys is because they get very hot to the touch and thought maybe they had been fried as well.

Thanks for any insite into this one.   

[Level42]

Yep the chips you mention at 7H etc. are PROMS.

I guess the buffer IC's for the yoke are the first thing to look at.

[lsneighbors]

Do you know where you can get new the proms from?  I'm guessing they would need to be preprogrammed as well. 

As far as the buffer chips do you have the IDs of which ones you think might be issues?

Thanks again for the help.

[Ummon]

Dude, '88 goes beyond 'several' years. That's over two decades.

[Level42]

The PROM number you indicate is correct (same on my working board-sets). On mine there's an Atari stamp over the original PROM text saying (C)1983 Atari and the Atari fuji logo on them. They are numbered 136021 and then each chip has a number from 110 to 113.

I'm not sure how hot they actually get during play. Remember that the board-set has a really big fan under it to cool it so if you run it on your test-bench it may get a lot hotter....

I know about these proms as I've recplaced them a good number of times while working with SW/ESB kits. You could drop Mark Spaeth an e-mail if you think they are suspicious, however did you run the test-mode ? If any of them would be bad, I guess you'd be reported that and the game is very likely to show it if anything is wrong with them.

I checked the controls section on the schematics and the yoke controls go directly to the A/D converter, no buffering (which makes sense since these are of course analogue values). However, there's a 74LS04 that triggers the sampling (START) at position 8K. Might be worth checking that one out/replacing.
Do you have the schematics ?

Since you replaced the pots, are you sure that they are wired up correctly ? Are they the correct Ohms value ? (Just asking the obvious). What does the game aim at in the trench scene when you start a game ? (I.E. Top-Left corner, Right-bottom etc.)

[lsneighbors]

Good point on the self test running through it shows no error so I'm guessing that would mean they are working.  I have the schematics but only in little blocks - terrible time trying to read them I wish I had a huge E size sheet showing the entire layout it would be easier for me to read.

I will look at the 74LS04 and check the lines going in and out and see what they might be doing.

I'm guessing I wired the pots up correctly I tried to remove each wire and replace as I removed it and looking at photos and wiring it seems correct.  I have a ground on one side center tap and positive on the other.  The voltage swings so it looks like it is working.  I got the rebuild kit from Bob Roberts if I'm not mistaken and they are the 5k pots as well as replacing the gears and connectors.

In test mode the cursor is at a 135 degree angle CCW about 1/4 of the way off of center  - Bottom Left quadrant.

Thanks again for the suggestions I will check in the '04 and replace it if the signals look bad.

[lsneighbors]

I think I may have found why the signal lines are so noisy.  After I pulled out the 74LS04 chip (checked some voltages and found one pin that looked like it was floating) I did some tracing and found that where '04 feeds over to the ADC0809 chip that there was no continuity.  Pulled out the ADC and found that the socket had 2+ bad sockets so I have ordered a new 28 pin socket as well as a new 74LS04 so hopefully (keeping fingers crossed) that this will finally solve the last problem I have had with rebuilding this Star Wars machine.

[Level42]

Cool ! And we always love pics of machines here, esp. if they've been stored for over 20 years

[lsneighbors]

I will get some pictures when its done.  I got it back in 1987 for $150 and it was not in great shape but playable and it was mine....  I had it sitting in my basement and then in storage since that time.  I'm in the process of replacing all of the overlays and hopefully have it back to it's original glory very soon.  Thanks again.

[lsneighbors]

Just wanted to update - WaHoo....  Yes the new socket and 7404 seems to have fixed the issue.  I now have full yoke control and will send it out to get sandblasted today so I can get it painted this weekend.

Thanks again.

[Level42]

Yesssssssssss ! Congrats !

A very good investment to buy that cab back then