(Topic ID: 249514)

No sound at all - Williams World Cup 1978

By stibbsd

2 years ago



Topic Stats

  • 7 posts
  • 3 Pinsiders participating
  • Latest reply 2 years ago by barakandl
  • No one calls this topic a favorite

You

Linked Games

Topic Gallery

View topic image gallery

Untitled (resized).png
55 (resized).jpg
20190824_064331 (resized).jpg

#1 2 years ago

I just got the Williams World Cup (1978) pinball machine from my sisters’ basement. It had been stored in a couple of boxes for the past 18 years. The batteries were still in the CPU/MPU, but I got them out and cleaned it up pretty well. There were a couple of fuses blown, but most of the wiring looks stable. However, I have a few existing problems. First off – I’m not an electrician and I will avoid soldering anything if possible. Also - this is my first pinball machine.

I’ve spent several hours with the manuals I’ve found online and seen a lot of pictures that match my machine. I’ve learned the diagnostics process and run through it several times to test everything I can find. Here’s the problems I have left to identify:

The sound on the machine is not functioning at all. I grabbed another speaker to make sure that wasn’t the problem When I run through test sequence 2 all the items seem to work except anything that should be playing a note through the sound board.
1) Verified 10J1, 10J2 and 10J3 are connected – cleaned them and re-seated them.
2) Checked the 10F1 fuse – it is fine.
3) Tried a different speaker.
4) Turned the volume up and town – I get a hum in the speaker when I touch the volume control – same as the new speaker as well.
5) I’ve run the tests on both the sound alternator settings.

Is there anything I can check before trying to replace the sound board? I’m looking for any suggestions to get this pin back to working order.
Thanks.
David

#2 2 years ago
Quoted from stibbsd:

I just got the Williams World Cup (1978) pinball machine from my sisters’ basement. It had been stored in a couple of boxes for the past 18 years. The batteries were still in the CPU/MPU, but I got them out and cleaned it up pretty well. There were a couple of fuses blown, but most of the wiring looks stable. However, I have a few existing problems. First off – I’m not an electrician and I will avoid soldering anything if possible. Also - this is my first pinball machine.
I’ve spent several hours with the manuals I’ve found online and seen a lot of pictures that match my machine. I’ve learned the diagnostics process and run through it several times to test everything I can find. Here’s the problems I have left to identify:
The sound on the machine is not functioning at all. I grabbed another speaker to make sure that wasn’t the problem When I run through test sequence 2 all the items seem to work except anything that should be playing a note through the sound board.
1) Verified 10J1, 10J2 and 10J3 are connected – cleaned them and re-seated them.
2) Checked the 10F1 fuse – it is fine.
3) Tried a different speaker.
4) Turned the volume up and town – I get a hum in the speaker when I touch the volume control – same as the new speaker as well.
5) I’ve run the tests on both the sound alternator settings.
Is there anything I can check before trying to replace the sound board? I’m looking for any suggestions to get this pin back to working order.
Thanks.
David

Send a picture of your sound board front side.

#3 2 years ago

I've posted a picture.

20190824_064331 (resized).jpg
#4 2 years ago

Based on the speaker hum changing with volume control the amplifier and power supply is probably working OK. Check for +5v on the bottom pin of the 7805 on the heat sink. Besides that hard to diagnose through the computer. Can't tell from the picture, but those sound boards are often using the really crappy scanbe IC sockets. You can try backing out the socketed chips half way and pushing them back down in the socket.

#5 2 years ago
Quoted from stibbsd:

I've posted a picture.[quoted image]

The pins are tarnished on Ic 3 the 6821 suggest replacing the chip.
re seat the sound rom Ic2 and 6808 Ic1 after replacing Ic3

55 (resized).jpg
#6 2 years ago

Great info barakandl and PINTEC. I'll give this a try, and post my results.

I've found this.

https://www.marcospecialties.com/pinball-parts/6821

#7 2 years ago
Quoted from stibbsd:

Great info barakandl and PINTEC. I'll give this a try, and post my results.
I've found this.
https://www.marcospecialties.com/pinball-parts/6821

This is a rare case where you cannot use a 6821 in place of a 6820 unless the board has been modified. If you go to IPDB and download the manual for Flash there is info about how to mod the board so a 6821 will work.

Untitled (resized).png

Soldering p39 and p40 together and adding the 10k pull down resistors is the most important part. The 4.7k resistor change says it improves sound quality.

Hey there! Got a moment?

Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside