Coffee-Mat Star Battle Pinball Repairs

Restoration/upgrades/fixes/fabrication of pins and vids
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sylvain
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Coffee-Mat Star Battle Pinball Repairs

Post by sylvain »

While always busy at work and at home with limited spare time available, managed to progress on this
interesting and rare circa 1978? or so early solid-state Coffee-Mat Star Battle cocktail pinball machine
that someone brought me to repair a few weeks ago. Not much info on the web on this one.
DSCF0065 (3).JPG
Opened the machine and placed the electronics on the side for further debugging
DSCF0065 (4).JPG
DSCF0065 (5).JPG
Initially nothing was working except for GI lights.
Transformer OK but there was no voltage at output of bridge rectifiers on the logic board.
Two out of the three bridge rectifiers were bad (opened) - replaced all 3 with beefier ones.
Now, voltage was appearing at the input of the +5V regulator, but still nothing at output.
The -10V regulator also had issues. Ordered proper replacement parts and replaced both.

+5V and -10V voltage supply were now OK, but the two player score displays only displayed '00',
middle displays were still dead, and center saucer hole solenoid was stuck on.
I also realized some CMOS chips were abnormally hot.

Replaced those 'hot' chips (and installed sockets). No more CMOS chips overheating afterwards,
but the machine still did not work properly. Pulled-out my old Micronta (Radio Shack) logic probe
and found a few more chips that had incorrect logic output for the state of their input pins.
More chips replaced. Player 1 and player 2 score displays now showing all '000000' as expected.
Whew, something bad must have occurred at some point in this machine's past.
DSCF0065.JPG
While the machine was getting mostly playable, the center displays still did not work.
Turns-out the issue was the center displays board's three F9368PC display driver chips - were bad.
Ordered, received and replaced (still with sockets). Eureka, 2 out of the 3 middle displays worked afterwards!
However, the 2nd display in the middle still did not work even with the new chip installed.
Quick troubleshooting indicated it did not get its expected +5V arriving on its supply pin,
although all connectors / pins were OK with no cold solder joints.
After further investigation, turns-out the P9 connector on the logic board has a manufacturing/design error,
as the pin 1 label is printed on the wrong side of that connector! Looked at the wiring and connector,
reversed it, powered-up, and whew, the center display finally worked.
DSCF0065 (2).JPG
But wait, there is more! Still no sound, even though all supply voltages arrived OK on the sound board,
potentiometers and the speaker are good, and capacitors tested good with an ESR meter.
Nothing overheating, but the amp chip did not appear to work, i.e. no hum when touching its input pin.
Ordered a TBA820 amp and replaced it. Also had to replace the LM3900 op-amp chip.
Most sounds work now, but not all - will follow-up, probably another chip either on the main logic board
or possibly one of the 741 op-amp on the sound board. In any case, I still need to replace U6 on the main
logic board as a prior tech added a replacement chip on top of the bad one and it looks like a hack - although it works!

Also fixed a prior harness wires cut that were badly respliced, replaced a few bulbs and adjusted a few switches.
Fun project for sure!

Some repairs do take time. Patience, investigation and research are key.
Keep on flippin' (and sometimes repairing :)
Looking for Bally Star-Jet, The Wiggler, Williams Magic City, Grand Lizard, Swords of Fury, 1986 Pinstar Gamatron, and a few others.
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Re: Coffee-Mat Star Battle Pinball Repairs

Post by cait001 »

Wow, cool pin and thanks for the writeup.
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Re: Coffee-Mat Star Battle Pinball Repairs

Post by Xylog »

Oh wow, that's my old machine! Picked it up many many years ago at the York Show in Pennsylvania. Brought it home on the roof of my Sunfire. Beautiful machine, but WAY beyond my tech skills to bring it back to life.

Glad to see it being brought back to life! :)
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Re: Coffee-Mat Star Battle Pinball Repairs

Post by sylvain »

Oh cool, thanks Xylog for this info. On the roof of your Sunfire? Wow, impressive!
...I am aware that the machine went to at least one other MAACA member before being traded to the person I am now repairing it for.
Small World indeed!
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: Coffee-Mat Star Battle Pinball Repairs

Post by sylvain »

For info:
I received a PM last night from a new MAACA member who owns a working Coffee-Mat Cosmic Wars with a few sounds missing too. Similar electronics. He was going to check electrolytic capacitors on his board.

Regarding the comment in the original post:
“I still need to replace U6 on the main logic board as a prior tech added a replacement chip on top of the bad one and it looks like a hack - although it works!“

His comment - thank you!:
"My main logic board has the same thing so it must be a factory thing."

Interesting. Therefore, this is probably a factory board modification or correction around that 74C00 chip.
A board 'barnacle' / manual rework at the time essentially.

Thanks again for the info!
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: Coffee-Mat Star Battle Pinball Repairs

Post by Azatotht »

Thank you Sylvain for reporting this in the thread, could be very useful to someone eventually.

As for the new member, welcome aboard and do not hesitate to post if you have anything else you may want to add to this thread.
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Re: Coffee-Mat Star Battle Pinball Repairs

Post by GILV »

Very interresting thread, yes, it could be very usefull for someone eventually, thanks Sylvain for all of the details.

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Re: Coffee-Mat Star Battle Pinball Repairs

Post by sylvain »

Thanks 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: Coffee-Mat Star Battle Pinball Repairs

Post by OTTOgd »

Awesome.

... but where's the gameplay video?!?

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Re: Coffee-Mat Star Battle Pinball Repairs

Post by Mrhide »

sylvain wrote: Tue May 07, 2024 8:07 pmA board 'barnacle' / manual rework at the time essentially.
la factory était en ta!
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Re: Coffee-Mat Star Battle Pinball Repairs

Post by Cjs001 »

Hi all,
I am the new member with the Cosmic Wars. As of yesterday evening I have the game back 100% working and I have 6 different sounds working now. I originally only had the A and B tones. I replaced the 3900 ic on the sound board and that gained me back the missing 4 sounds. The sounds I have are: 1. A tone 2. B Tone 3. Extra Ball awarded sound 4. Kickout hole Sound 5. Free Game awarded Sound 6. Coin Drop Sound

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Re: Coffee-Mat Star Battle Pinball Repairs

Post by Cjs001 »

Here are some pictures of my Cosmic Wars.
Attachments
IMG_4109.jpeg
IMG_4108.jpeg
IMG_4113.jpeg
IMG_4115.jpeg

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Re: Coffee-Mat Star Battle Pinball Repairs

Post by sylvain »

Well done Cjs001, Bravo!

I think I have all six sounds on the Star Battle now - the Tone A & B potentiometers needed to be adjusted.
Need more time to test and confirm.

The confirmed tones produced by this Coffee-Mat Star Battle are:
1- Credit (coin switch)
2- Tilt
3- Free Ball (Extra ball awarded)
4- Center hole
5- Tone B
6- Tone A
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: Coffee-Mat Star Battle Pinball Repairs

Post by TwilightZone »

Well done, Sylvain! I had this one in my basement for awhile. Was going to turn it into a coffee table, but thought it was too nice. Great to see it's now working!
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