Help with repairing System 7 boards?

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Tansit
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Help with repairing System 7 boards?

Post by Tansit »

I’m having issues with my Cosmic Gunfight, and I’m hoping someone could help point me in the right direction. Sorry for the long post...

It was non-playable when I bought it, but I gave the game a quick once over and made a few repairs that I could handle. In the end I was able to get it to boot, pass diagnostics and play a couple of quick games, but now it’s given up the ghost as the previous owner (a super nice guy) had told me to expect.

On power up it now boots into audit mode and the flipper control relay clicks on the driver board. The MPU throws an error code 9 - apparently either the memory protect circuit, coin door (ruled out), or a bad chip (most likely). Also for the first few seconds the speaker hums loudly then goes quiet.

I’m still quite green and not sure quite where to start. I’ve also learned that I have very little appetite for board work (plus I know my limits), and along with fixing these issues all of the boards are in need of bulletproofing - new caps, socketing failed chips, upgrading the 2w resistors, display voltage mod, etc. Batteries are still onboard, but thankfully there is no acid damage that I can see.

Is there anyone around that I can hire to do the board work or know where to find another set of solid system 7 boards that have already been updated? Does anyone have a rough idea of how much work like that would cost?

I understand that there will likely still be other issues in the game, but I want to start with rock solid boards and take it from there. I’m still fact finding at this point, but would like to know how much to budget and who to contact when I’m ready to pull the trigger. Thanks!

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sylvain
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Re: Help with repairing System 7 boards?

Post by sylvain »

Check the battery holder in case there was corrosion at some point, e.g. the 4.5V batteries voltage (3x1.5V) not always getting to the MPU memory - booting in Audit mode.
Are the batteries still good?

On power-up, the quick loud hum is normal on those Williams.


-Sylvain.
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
Collecting & repairing electro-mechanical and solid state pinball machines with quality and care for 40+ years already.
Serious and fun hobby, powerful nostalgia !

Tansit
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Re: Help with repairing System 7 boards?

Post by Tansit »

sylvain wrote:Check the battery holder in case there was corrosion at some point, e.g. the 4.5V batteries voltage (3x1.5V) not always getting to the MPU memory - booting in Audit mode.
Are the batteries still good?

On power-up, the quick loud hum is normal on those Williams.


-Sylvain.
I’m glad the hum is normal, I thought it might be an issue with the soundboard. I checked the holder and there was some corrosion, I buffed the contacts well and tried two sets of fresh batteries, no dice.

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sylvain
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Re: Help with repairing System 7 boards?

Post by sylvain »

You need to measure the voltage of the batteries arriving on the MPU board - often one or more contacts on the battery holder are gone.
Once measured 4.5V or higher, with the cash door opened turn the machine on, wait a few seconds, then turn it off and back on,
it should get out of audits if all is well.
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
Collecting & repairing electro-mechanical and solid state pinball machines with quality and care for 40+ years already.
Serious and fun hobby, powerful nostalgia !

Tansit
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Re: Help with repairing System 7 boards?

Post by Tansit »

Thanks for your ongoing help! Okay, so I’m getting voltage into the board from the batteries I believe - again, I’m a newb. With the game off, I’m getting ~4.7v on test point 7 (CMOS Ram).

TP 3 (memory protect) however is low according to the info I’ve found - supposed to be 5v, I’m reading 3.7v. And it gets stranger...

In cycling the machine off and on again (not touching the board at all) a flipper coil locked in me. It did it twice when powering on, then stopped locking. I checked the fuses and they haven’t blown...

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Re: Help with repairing System 7 boards?

Post by Tansit »

The 3.7v on tp3 was measured with the coin door closed, and it tested 100mv open - shouldn’t that be an open circuit? Could that point to a bad chip?

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Re: Help with repairing System 7 boards?

Post by sylvain »

I do not have the time to pull a Sys7 schematics now (busy today), but:
- to have a FLIPPER coil energized at power-up, there needs to be two things happening:
- incorrect state of the flipper enable relay on the board
- AND, the corresponding flipper button switch shorted.

Is the game booting now, or still in audits, or not booting at all?
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
Collecting & repairing electro-mechanical and solid state pinball machines with quality and care for 40+ years already.
Serious and fun hobby, powerful nostalgia !

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Re: Help with repairing System 7 boards?

Post by Tansit »

It is still in audit mode unfortunately. I have schematics, is there something I should look for?

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Re: Help with repairing System 7 boards?

Post by sylvain »

Could be the static-sensitive 5101 CMOS RAM 22-pin chip on the MPU, or other circuit around the memory protect possibly.
Strange that it mostly worked earlier and now no more.

Here's one reference example post on pinside:
https://pinside.com/pinball/forum/topic ... audit-mode
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
Collecting & repairing electro-mechanical and solid state pinball machines with quality and care for 40+ years already.
Serious and fun hobby, powerful nostalgia !

Tansit
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Re: Help with repairing System 7 boards?

Post by Tansit »

Apparently this is the kind of thing that the original owner was experiencing. Ever since he pulled it out (after a decade of storage) it would behave erratically but occasionally you could still get it to work for brief periods.

I’ll test the 5101 voltage as outlined in the post and see if there’s a fault at the diode or battery pack. The boards look mostly original in terms of components - the numbers don’t match so they’ve been replaced at some point, but there are only a couple of socketed chips and no recent caps anywhere. Could be all sorts of gremlins hiding in there.

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Re: Help with repairing System 7 boards?

Post by Tansit »

So I was just able to get it out of audit mode and into attract mode. The quick on off worked this time when I tried it - I don’t think I was doing it fast enough the first time. I guess that means that the 5101 is okay, or at least is working for now. I have a feeling that I may be on borrowed time though.

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Re: Help with repairing System 7 boards?

Post by Tansit »

I think that’s the right approach, I don’t want to chase my tail or end up with damage because of dodgy PS components or something else preventable. Now that I have gotten it running again with Sylvain’s help, I would like to keep it that way :)

I had stumbled across vids bulletproofing guide on pinside when I had my Flash (which I traded for this CG) and actually ordered a bunch of those components but never installed them - I gather that many of those parts are still used on the system 7 boards. But I soon realized that I really don’t like doing board work, and that it would be worth it to me to hire someone who can do it properly.

Also it looks like other things such as the sound board caps are all original, as well as those 2w resistors on the driver board (with their coatings peeled off and plenty of scorching behind them) not to mention a few suspect headers and getting the batteries off the board. Beyond identifying some of the basic things that need to be done, it’s beyond my scope to actually do it. Is there someone that could help me with that bulletproofing work?

Edit - I just looked in my parts bin, and since my Flash had most of the big stuff done by it’s previous owner, the parts I had ordered are only marginally useful. Mostly resistors that I had purchased with big ideas of overhauling the master display board, and spare transistors/predrivers.

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