(Topic ID: 83883)

System 80 Sound Board Dead! Need technical guidance!

By Pinwiz1985

8 years ago


Topic Heartbeat

Topic Stats

  • 12 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by pinwiz_pa
  • Topic is favorited by 4 Pinsiders

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#1 8 years ago

Starting a new thread on this to get some exposure on pinside. So I rebuilt the entire power chain of BH, new BRs, rebuilt main PSU board including the sound PSU, repined connectors, etc. This is for a friends machine.

His LM379S amp burnt out as the heat sink was missing. So I replaced that with another LM379S to no results, and trying the LM1875T mod yielded no sound.

I replaced all the dry capacitors on the board, but somehow I blew up the S&S board! I don't know how I did it but I did! The voltages are correct at the S&S power supply. I had the LM379S installed (being aware of pin 1 location) and installed the board. Soon as I did that within 5 seconds I lost the 5 volt and 12 volt indicators on the power supply. Nothing popped or burned as I shut it off quick enough not to cause damage. I unplugged the sound board and the game powered up fine with all the voltages present.

Put the S&S board on my computer bench power supply, and the output at R16 its repeatedly saying "FAILS, FAILS, FAILS."

I don't want to start blindly throwing parts at it. What does the error message mean? Did I blow both EPROMS? The 6502 MPU? The 6532 RIOT chip? HELP!

#3 8 years ago

BUMP! Need some help if at all possible

#4 8 years ago

I like to go for connector issues first before looking for board repairs, it helps to keep from chasing your tail (so to speak).

I'm not real up to speed with sound boards like I am on other parts of System 80 but I'll try to help. Posted are sound board test procedure pics of pg.18 in the Black Hole manual (if you don't have it). According to what I see there, when you hear a "fail" over and over, this would indicate to me that one or more of the sound lines are missing to the sound board. I think I'd install new crimps in the A6J1 and A3J5 connectors since they always looked tarnished/cooked (I don't like the punch pin type of connector anyway, they fail too much).

If you still have the "fail" problem after those connections are solid, take a look at Z13 (7404) on the A3 driver board.

If that looks good, you will have to meter test the input sound lines (1, 2, 4 & 8 ) from Z13 through the A3J1 to A1J4 connector up to Z31 on the A1 CPU board. Install new crimps in the connector if you have a break in the line there and re-tin the 4 left pads on the component side of the board (these are the sound lines).

If you still have issues, look at Z31 (7408) on the A1 CPU board, it is the sound control for the game. If you go all the way through this and still have a problem, that would indicate that all is now good and then it'll be time to dig into the sound board for the problem.

Steve

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#5 8 years ago

Okies, I'll look into Z31 on the MPU board and Z3 on the driver board for sure. I noticed before the sound board shit itself that you had to let the game "warm up" before it would start a game.

Its not the connectors as I've already repined them. I believe my problem exists on the sound board itself. I changed all the caps with the proper sized ones. I thought that my game not starting was a dried cap on the sound board because the game started fine without the sound board connected.

I got this sneaking suspicion that I may have a bad RIOT chip, 6502 MPU, and/or EPROMs. My audio amp not working is another mystery all together. That may have caused the final failure too. Powering up the board from an external power supply gives me the "fails" error message too.

Much as I don't want to shotgun this thing, the cost of a refurbished one vs the cost in parts is a large difference. The time commitment to work on replacing parts I'll write off as a learning experience.

Guess its time for me to invest into a decent logic probe that wont break the bank if I'm going to start testing IC chips and signals.

#6 8 years ago

I've seen yours "help callings", BUT it's very hard to give some "smart" suggestions AFTER induced
faults that occurred in repairing electronic boards.

Gottlieb's sound/speech boards are definitely a kind of "happynes" to work on them, my suggestion
would be to check +5V and +/- 12V... (again )

And strategy would be....

On sound board set ALL DIP SW 's SB1 to OFF

DISCONNECT connectors A3 - J2 AND A3 - J5

--- Power ON

Check voltage levels on U16 (sound board ) like this...

pin 1 - (e.g.) HI

pin 2 - .....

....etc..
..

pin 14 - HI (must be )

Also check level on U17 -pin 8 (only ! )

This measurements will give a pretty clearer situation

Greetings from Croatia

#7 8 years ago
Quoted from Pinwiz1985:

Guess its time for me to invest into a decent logic probe that wont break the bank if I'm going to start testing IC chips and signals.

+1

#8 8 years ago

Hey Cro, thanks for the tips. I agree this repair is self inflicted. I just didn't want to start poking around on the board blindly and throw parts at it. There is a systematic way to approach troubleshooting this board, much like a computer. Maybe a wire crossed or voltage was off. At this point, my buddy was able to find a working replacement sound board. I'm still gonna continue to diagnose and fix the board on my dime since I blew it up. I'll keep everyone posted on the repair.

2 years later
#9 5 years ago

...and he never did

3 years later
#10 2 years ago
Quoted from Pinwiz1985:

Hey Cro, thanks for the tips. I agree this repair is self inflicted. I just didn't want to start poking around on the board blindly and throw parts at it. There is a systematic way to approach troubleshooting this board, much like a computer. Maybe a wire crossed or voltage was off. At this point, my buddy was able to find a working replacement sound board. I'm still gonna continue to diagnose and fix the board on my dime since I blew it up. I'll keep everyone posted on the repair.

Any updates pinwiz?

8 months later
#11 1 year ago

Hey everyone, sorry I have not updated this post in forever. Honestly I missed it entirely. For those reviewing the thread in later times, ultimately I gave up and found a working board used for a decent price.

I still have the original board, i'd be willing to give it away, just need to pay for shipping. If at the very least can be used for parts. My friend sold BH a few years ago.

#12 1 year ago

I would be interested in that sound board if still available.

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