(Topic ID: 242823)

System 11A music/sound problem


By Gnatty

35 days ago



Topic Stats

  • 23 posts
  • 10 Pinsiders participating
  • Latest reply 18 days ago by slochar
  • Topic is favorited by 1 Pinsider

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#1 35 days ago

Just finishing up a project Millionaire and I’m down to my last issue. Randomly the background music will either cut out or hang up on a note during play. Speech always works but the blip in the music and/or sounds is random during play. When ball drains, bonus counts down and next ball is ejected, sounds and music return. I have re-seated those chips, connectors etc. with no luck, any suggestions what to check next would be appreciated.

#2 35 days ago

Can you post a picture of your CPU board?

#3 35 days ago
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#4 35 days ago

Also, when it cuts out, sometimes the start up Bong sounds off.

#5 35 days ago

Have you tried reseating the 6802 at U24 on the CPU board?

#6 35 days ago

I have spare working sounds boards if you determine that is the issue.

#7 35 days ago
Quoted from PinballManiac40:

Have you tried reseating the 6802 at U24 on the CPU board?

I’ll try that.

#8 35 days ago

Reseating the 6802 at U20 seems to have helped after playing a game real quick, I’ll test it out further this week.

#9 35 days ago

May want to go over the IC pins with a pink pencil eraser if it acts up again. But be careful not to put too much pressure on the legs and bend them.

#10 35 days ago

I had found quite a few bad Hitachi 6802 (that brand you have in U24 now) fail. Hopefully, this is not one of those such times.

#11 35 days ago

Background music and the "bong" are generated on the remote sound board, not the CPU sound section, however the commands to that sound board originate from the PIA on the CPU board that is just below the battery holder. That PIA is controlled by the main processor, not the speech/sound processor at U24. If there are corroded traces this could cause some of the sounds from the background music board to not initiate or possibly initiate the wrong sounds. However that shouldn't cause the background sound board to reboot (the bong is the board booting up) and hanging on a note is likely that board locking up.

Inspect the small ribbon cable and the are on the CPU around the battery holder from the PIA to the cable. Reseat that ribbon cable at both ends and reseat all the connectors on the background sound board. Reseat any socketed chips on the background music board.

So typically on most pinball sound boards that generate music the following happens when it experiences a reboot. The command to play music only occurs once. Usually at the start of a ball or when the game changes states, i.e. ball in play to end of ball or after locking a ball or starting a new mode or starting multi-ball. So if the sound board reboots mid-game, it will make the boot-up sound (a bong for Williams games, a short speech quip on DE games). The board will continue to receive new sound cues so it will continue to talk or make sound effects, but the music will not restart until a change in state happens, i.e. end of ball or start of multi-ball.
You can see this on some (most?) system 11 games if you quickly press the start button when powering on the game. If you start the game prior to hearing the sound board boot-up bong, the sound board will have missed the start music cue and will then play most of ball 1 without any music. once you drain the ball the music starts on ball 2.

As PinballManiac40 said those Hitachi CPU chips (and Hitachi 6821 PIA's) tend to fail more frequently than the Motorola. Just note that if you change from the Hitachi 6802 to the Motorola 6802 I believe you have to change a jumper on the CPU board.

#12 31 days ago

No change, music still drops out or holds last tone consistently.

#13 31 days ago

you can also swap the sound board ribbon cable around end to end and see if it persists.

Seen a bad ribbon cable cause this exact issue . Do as Kbliznick says and reseat socketed chips like the eproms etc. Plus reseating the cable many times may help as it cleans the terminals off the more you do it.
Never hurts to get a new ribbon cable though. Cheap way to make sure its not the problem. You should inspect the pins on the boards too. Seen the odd pin missing before and some not making connection due to poor factory solders.

#14 31 days ago

Thanks hawk, i did swap cable end to end. I think I’ll order a new cable however. I’ll try eliminating variables one at a time.

#15 31 days ago

Could this be a 5v issue coming from
Ps?

#16 31 days ago
Quoted from Hawk007:

reseating the cable many times may help as it cleans the terminals off the more you do it.

Better to get a new ribbon cable. Reseating the cable also wears and stretches out the female sockets of the connector, which can make a poor connection just worse. These are not meant to be plugged and unplugged repeatedly. http://www.pinrepair.com/connect/#worn

#17 31 days ago
Quoted from wayout440:

Better to get a new ribbon cable. Reseating the cable also wears and stretches out the female sockets of the connector, which can make a poor connection just worse. These are not meant to be plugged and unplugged repeatedly. http://www.pinrepair.com/connect/#worn

yes thats why I said to get a new cable if reseating helps. Its always best to replace it. they are cheap.

#18 31 days ago

if problem persists check your continuance between the board connector pins for the ribbon cable and the legs of the 6821 pia that controls the sound data - iirc there a RN in-between the two, if thats all good, then plug in the ribbon cable and ring it out, but sounds like dirty pins or worn out ribbon

#19 29 days ago

I had a very similar problem on my Pinbot. My issue ended up being low (high?) -12v coming from the power supply. It was -10v but it needs to be at least -10.5v or it can cause resets, and seems to particularly affect the sound board. This can be tested on the three test points in the center of the power board, left -12, center ground, right +12v.

What solved it was replacing the capacitors on the power supply as they were original and had dried out.

#20 23 days ago

Thank you guys, I ordered a new cable and will also rebuild the power supply and report beck. Much appreciated

#21 20 days ago

Just checked my Pinbot Manual and I had it backwards, it’s + not -:

Unregulated +12v on the power supply, TP3, should not go lower than +10.5 or resets will occur.

#22 18 days ago

Replace the ribbon cable, no change, replaced the 6802 at U24, no change. I guess it’s now replacing caps on power supply next.

#23 18 days ago

Had same problem on pinbot board.... it was the eproms. They verified good, but I burned a set anyway after doing much of what you've been doing, and that fixed it. As a test a couple weeks later swapped the suspect set back in (to make sure it wasn't something goofy with the IC sockets) and sure enough, issue came back.

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