(Topic ID: 228662)

Gottlieb Sys3 Sound not working


By Larrykaye

6 months ago



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  • 11 posts
  • 5 Pinsiders participating
  • Latest reply 6 months ago by Larrykaye
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#1 6 months ago

I am working on a Shaq Attaq and the sound board(s) are not working. They do not work with the game ROMs nor with Marco's test ROMs. The LED on the main board just stays on. I have measured (literally) every IC pin with a scope and all have 'valid' TTL levels. The address and data busses are running. These tests were done on the bench. With the test ROMs both 'A8' LEDs and the on board one glow because they have a waveform rather than a fixed level. I socketed both RAM chips and, while the original ones were out, checked them and they were fine. I changed them anyway since I had new ones. Any suggestions on what else might be good to check?

Thanks, as always.

#2 6 months ago

It seems like you are looking at a lot of different things and changing a lot of parts. I'm just not sure I am clear on your text and have some questions of the troubleshooting done so far.

I assume that since you have it on the bench, the aux power supply (final amplification on that board) has been completely ruled out and you have no analog out of the RCA connector on the auxillary sound board, is that correct? What points have you looked at with a scope to check the audio path on the auxillary sound board? Do you have analog out the serial DAC? It would help if we found out where the signal is lost so there is some starting point.

#3 6 months ago

Yes, I looked at everything digital that might be causing the problem. The only replaced parts are the two RAMs. Since the problem is that the board will not boot, I have not looked at anything analog. With the boards in the game and the game ROMs installed, I get a low frequency buzzing noise at turn on (so the audio amplifier is working). This is a square wave output from the main board. It goes away if I reset the board. There is no signal on the RCA jack on the aux board. On the bench, I did not hook up the aux board as I interpreted the test ROM instructions to say it was not needed.

#4 6 months ago

Not sure if this your sound board's exact issue, but a couple of chips were bad in addition to ram when I last encounted a dead sound board:

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_3#Mixed-Up_6-pin_Power_Supply_.26_Driver_Board_Connectors

#5 6 months ago

General process for System 3 sound boards...
...Reset working?
...clock signal working?
...ROMs valid?
...RAM working?
...address and data lines working?

Proper boot will cause the LED to blink.
You’ve been through most of this.

Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info

#6 6 months ago

I have not had time to check into ForceFlow's suggestions and as Chris noted have pretty much checked all the things on his list. It would be interesting to check the Game ROMs. Does anyone know of a source for the check sums? With the code under Gottlieb copyright I can't get that to verify my ROMs. I suppose it is always possible that I have a bad Game ROM and that something is wrong with the test ROMs that I burned so that neither will make the board work.

#7 6 months ago
Quoted from Larrykaye:

I have not had time to check into ForceFlow's suggestions and as Chris noted have pretty much checked all the things on his list. It would be interesting to check the Game ROMs. Does anyone know of a source for the check sums? With the code under Gottlieb copyright I can't get that to verify my ROMs. I suppose it is always possible that I have a bad Game ROM and that something is wrong with the test ROMs that I burned so that neither will make the board work.

You can grab the roms from vpforums.org....unofficially of course.

#8 6 months ago

Unfortunately (unless I missed it) they do not have any of the Shaq ROM images. While I am on the checksum quest--does anyone have them for Marco's test ROMs (just to be sure the download isn't corrupted). Last I was in contact with him he was on holiday so I don't want to bother him right now.

#9 6 months ago
Quoted from Larrykaye:

Unfortunately (unless I missed it) they do not have any of the Shaq ROM images. While I am on the checksum quest--does anyone have them for Marco's test ROMs (just to be sure the download isn't corrupted). Last I was in contact with him he was on holiday so I don't want to bother him right now.

Hmmm... I havent been on there in awhile, but it looks like they were pulled. Sorry about that. I am pretty sure I have the rom images, let me see what I can dig up.

#10 6 months ago

Thank you Marco for the information I needed. Now that I know the ROMs are OK I went back to signal checking. The Y section processor has the R/W line always high with the program code ROMs or the test ROMs. Could be not reading the program code and therefore waiting forever or maybe a bad 65C02. Much as I don't like shotgunning parts, I ordered a few 65C02s.

#11 6 months ago

Just to close this out--the board is now working. In addition to a bad 65C02, there was a bad 74HCT245. Thanks to all for your suggestions. Just as a side note--I would not recommend taking ICs out of that board unless you have some experience in doing that. These were really difficult to remove with small traces and small holes for the IC leads.

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