World Cup Soccer
Bally, 1994You're currently viewing posts by Pinsider arolden.
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I think I have a very similar issue to you. Just moved my games and have lots of static and distortion from the speakers but only when playing a sound. I confirmed the sound board was the issue as the problem also occurs in Demolition Man when I swap the board and ROMs.
Did you ever resolve this?
I've only replaced the 1uf electrolytic caps. Solder on the 10k uf caps is intact. In fact all the solder joints look good. No leaking caps on this board either.
Quoted from JeffHecht:Therein lies the mystery. On the first one of these that I encountered, I replaced a ridiculous number of components (capacitors, amplifier ICs, op amps, regulators, etc.). NOTHING made a difference and the original parts all worked perfectly with the modification. Troubleshooting should be deliberate and logical. If we think about this in that frame, there is likely an unbalanced load on the power supply rails, which manifests itself as an imbalance in the voltages. I would love to be able to go back in time and see what the rails looked like in a brand new board. The nice thing is that with this simple modification, it doesn't put a significant increase in load, but it forces the voltages to stay balanced now, and in the future.
Please let us know how your sound rail voltages look in Shadow and, if you decide to do the modification, if you notice a difference in the quality of sound.
I experimented with this today. I measured the voltages on JD and they are the same on both rails. Pics from DM (fully working) for comparison.
I will try the modification anyway and report back.
IMG20211027200939 (resized).jpgIMG20211027201000 (resized).jpgIMG20211027201424 (resized).jpgIMG20211027201510 (resized).jpg
No change after installing the bleeder resistors, although the voltages are good so I'm not sure what I expected to happen.
I already removed those capacitors as a first step. Unfortunately, no effect.
The odd thing is it seems to be an inconsistent problem. Sound seems to improve after the game is left on for a while. Maybe this is a problem with some of the caps after all. I will replace a few others and see if that makes a difference.
Yes, I have made some progress on this. I realised that the sound improved after the game was on for 10 minutes or so. That led me to believe that the problem was caused by the cold, and as the components heated up, the sound improved. I tested this with some freeze spray today. I sprayed most of the board components and found that sound quality worsened a lot when spraying U20 (AD1851 converter). When I used a heat gun to heat U20 up, the sound improved.
So I am assuming at this point that U20 has somehow failed. I'm going to try reflowing some solder and replacing the caps associated with U20 and if that doesn't work I'll order a replacement. Will keep his thread updated.
Small update. I can't find a copy of WPC-DCS schematics anywhere, so I had to trace the board circuits manually. John's thread here was a great help: https://pinside.com/pinball/forum/topic/repair-log-ngg-wpc-95-av-board
I found that the 79L05 regulator was only putting out -4.8v instead of -5v. I cut the output leg of the regulator and confirmed that the voltage was still low when it was out of circuit. I confirmed the voltage coming into the board was good, so I figured I had a bad -5v regulator. I replaced it, and I now have just above 5v and -5v coming out of each regulator respectively, but the issue still remains.
At this point I am still suspecting the AD1851 so I replaced the small ceramic caps associated with it at C10-13, but this made no difference. I have ordered another AD1851 but it will take a while to get here. Will update again then.
Quoted from altan:arolden I tracked down a clicking / popping noise on my TZ several years ago and it turned out to be a voltage issue caused by a bad cap that only tested poorly under load. I know this isn't a DCS board, but concepts can still apply. I've got it written up here https://www.aaarpinball.com/TwilightZone/TwilightZone.htm under "Clicking / Popping Sound Problem".
Maybe it’s interesting? Best of luck with your continued search for the root problem!
Hi altan,
Interesting article. Unfortunately I have already replaced all of the electrolytic caps on this board, so the issue lies elsewhere. But thanks for the suggestion!
Currently awaiting some replacement AD1851s to see if they make a difference.
Quoted from solo14:Hi arolden,
I'm facing the same trouble with my World Cup Soccer since few months. I have already replaced all electrolytic caps and resoldered all connectors on the audio board.
From what I understand reading quickly, I have to replace the 1851 to solve the problem. Could you confirm?
Here it is a video of the trouble.
Thanks
Yes that's right. Let us know if that fixes it!
Quoted from solo14:Bu I see on your photo that you alse repalced caps for the AD1851 voltage supply.
Before or after fixing the problem ?
I replaced the caps before I installed the 1851. The caps weren't the problem.
The only other issue I had was that one of my regulators was starting to fail. Check the voltages being output by the 79L05 and 78L05. Should be -5 and +5 volts respectively.
Your issue seems a little different in that you can still hear the callouts and sound effects. There is just some static in the background.
Quoted from Phantasize:I had a problem that sounded 100% identical to what arolden was experiencing. Really bad when cold, but after 10-15 minutes got noticeably better. From a warm state (with sound like 80% ok), I tried using freeze spray on U20 (with the machine powered off), and then powered it back on. And the sound was REALLY distorted. But after a couple of minutes it went back to being 80% ok. And I also felt like I could impact the level of distortion when touching U20 with my finger.
So I pulled the board, and reflowed U20. And after putting the board back in the machine, the sound was clean and crisp. YAY!!
Hopefully my problem is fixed now, but if it returns I will update this post.
Thank you to OP and arolden for your descriptions and write-up's. Without those, I would definitely still be debugging my board.
For reference, here is what my problem sounded like:
Good to hear! Glad the information was useful.
Quoted from Phantasize:Well, it seems I was a little too fast... The problem is still there, although not nearly as severe when cold as before.
Perhaps reflowing heated up something inside the chip itself that made it better, but not perfect. So I am guessing a U20 replacement could still be a good idea?
arolden I don't know if you tested this... But after replacing your U20, dit you try hitting it with freeze spray again, to see if it would affect the sound with the new chip? If you did, and it did not affect the sound, that would be a good pointer for me to also replace my U20.
I didn't try freezing it again after I installed the new one. I'll try and test that on the weekend for you.
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