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Zaccaria Locomotion - loud intermittent noise, goes during gameplay(video included)

David_Vi

David_Vi

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DaveTheTrain
Hey all!
It's me again, you know... That guy who owns the Tech support forum now.

My third screwed game is Locomotion.
I kept this one under my belt as I didn't want to overwhelm you all.

Had various issues, probably caused in transit and no fault of the seller, all fixed with the great guidance of @Zaccaria Keith - huge thank you.

There's one issue that wasn't there initially...
This god awful noise
See video

0 new items by David Bowery

photos.app.goo.gl photos.app.goo.gl

It goes away when you start a game and sometimes doesn't happen at all. It's intermittent but more likely to be there than not.
It even comes through with the volume down.

I thought I'd put it out there as it seems to be one of those issues that someone might have experienced and therefore has the solution.

Before this noise I was getting a buzz or grounding type hum that would get louder then go when the machine is moved (might have been a coincidence).

This noise doesn't sound like grounding issues , but I don't know. If you think it might be, how do I diagnose it or fix it?

It's a damn horrid noise that's for sure!
 
It doesn't do it with the sound board ribbon plugged in. Any ideas what to check on the sound board?
 
I thought I'd update on this as it's still ongoing and it's starting to get me down. Which is sad as Claire bought this game as a surprise, but it's turned into a bit of grief.

Luckily @Zaccaria Keith has been a hero in his help over the past week with helping diagnose and is offering to look at my boards if it comes to it.

In the mean time I'll update and see if anyone has any clue..

The noise appears to be a stuck sound effect.
It appears on power on then goes when a switch is activated that triggers a different sound effect (eg. the start button or coin chute switches )
It then comes back when you get any of the 3 station switches but goes either straight after the ball exits the station switch or when another switch is hit (I think having background sounds on influences this but need to double check).

My novice brain theory is a sound effect is stuck that is specific to the stations and powering on. (I don't remember but I think the game did a steam whistle effect when powered on that faded out , but it's been so long I don't remember).
The thing that might put an end to that theory is you get the same or similar effect when dropping a station drop target but that plays as expected.

Absolutely any ideas are welcomed.


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Screenshot_20220328-151438_Drive.jpgScreenshot_20220328-151353_Drive.jpg
 
I don’t know the answer. But doesn’t sound like a stuck on effect to me. Sounds more like interference picked up by the sound board. Possibly pick up from the displays? Just try removing the fuse that powers the displays and see if the sound is still there.
 
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pinballmania said:
I don’t know the answer. But doesn’t sound like a stuck on effect to me. Sounds more like interference picked up by the sound board. Possibly pick up from the displays? Just try removing the fuse that powers the displays and see if the sound is still there.
Click to expand...
We've tried removing the displays, didn't do anything😔

I assumed interference originally but why would it only affect one sound?
 
what happens if you disconnect CN1 - ie no signals from the cpu to the sound board? does that stop the noise?

If so then perhaps the issue is the output from
the cpu board - can you post up the schematics for that?
 
AlanJ said:
what happens if you disconnect CN1 - ie no signals from the cpu to the sound board? does that stop the noise?

If so then perhaps the issue is the output from
the cpu board - can you post up the schematics for that?
Click to expand...
No sound at all.
Heres schematics. It's too big for me to screenshot without losing quality

Zaccaria_1981_Locomotion_Schematics.pdf

drive.google.com drive.google.com
 
I would test the outputs of U34, i have t had long to study the schematics but it looks like that’s the output to the sound board (as well as to the interface board)
 
It would be nice to rule out interference though. I did have a ground hum that would grow in volume then go away beforr this issue occured
 
AlanJ said:
ps is there a sound test switch on the sound board? if so does it play the correct sounds?
Click to expand...
Yeah, SW1 on the top right of soundboard runs a test. It goes through the sounds but that noise remains in the background constantly which is different to when I hit switches on the pf
 
AlanJ said:
I would test the outputs of U34, i have t had long to study the schematics but it looks like that’s the output to the sound board (as well as to the interface board)
Click to expand...
Test in which way?
 
David_Vi said:
Yeah, SW1 on the top right of soundboard runs a test. It goes through the sounds but that noise remains in the background constantly which is different to when I hit switches on the pf
Click to expand...
not sure i understand? so when it plays each test sound, is the horrible noise there as well at the same time?
 
Your board photo looks like it's got a hack from the 76477 pin 15 to the chip on its right. Maybe that's come loose? Might be worth cleaning it up.

Also looks like you could temporarily remove R51 and R58 to isolate that portion of the circuit - might help bisect the issue.
 
Fubar said:
Your board photo looks like it's got a hack from the 76477 pin 15 to the chip on its right. Maybe that's come loose? Might be worth cleaning it up.

Also looks like you could temporarily remove R51 and R58 to isolate that portion of the circuit - might help bisect the issue.
Click to expand...
I took that hack off and put it back as it made no difference except seemed to stop the chuffing effect.

Keith suggested trying to remove R58, I did to no effect. Haven't tried the other.

Going to send it to Keith at the end of the week but a little worried it could be the cpu board or interference
 
I had a think again. it’s more likely to be the sound board, but the cpu board does put out a couple of data lines that only seem to be used by the sound board.

send the sound card off to Keith is probably the best move
 
As Grizz said make sure the boards are screwed nice and tight. Remove the power from the sound board does the noise go away? (Do this before powering on) Sounds like interference to me.
 
Arv said:
As Grizz said make sure the boards are screwed nice and tight. Remove the power from the sound board does the noise go away? (Do this before powering on) Sounds like interference to me.
Click to expand...
Removing the power doesn't allow the game to boot fully. You lose the displays too.
Oddly when you plug the power back in you hear a little beep even though game is off.
 
Tried removing r51, nothing.


Sven Normansson said:
sounds more like a motor to me.
Click to expand...
It's whiny.



Folks a query, the ground braid between the transformers and speaker. Is that supposed to have continuity to the braid along the cabinet?
(It doesn't)


Also ignore that fuse. It caused the backbox GI not to work as it wasn't in properly... I tried removing it to see if the noise went away (as it was one of the last things I fixed before the noise arrived... And it shattered.
 

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I used a bit of wire to add continuity to the ground braid that was all alone. It didn't change anything first time i turned the game on.

I thought as the noise is barely present during gameplay and a coin switch can stop it at start up I'll just put backglass and playfield glass back and try to enjoy the game until @Zaccaria Keith is home and able to take the sound board for testing.

Then guess what..
https://photos.app.goo.gl/VBS4mUV3TnUMsnKw5
Noise appears for a split second but goes away.

Why?!
I haven't done anything!

Multiple times I have put the boards back and shut backbox and tried it out, with the unwanted noise making endless appearances.

Now its gone.
I'm grateful but I have absolutely no idea what I did. Because I did nothing.

Except that ground braid but it didn't make a difference at first .

Will see if it remains ok, don't want to get my hopes up!
 
A separate audio ground might be intentional to avoid noise making it to the speakers.

If bridging grounds solves the problem that may indicate some sort of signal integrity issue? Looks like the audio board gets ground from both CN1 and CN2, is that creating a loop in the system? You could test that by disconnecting pin 4 on CN2. Or I could be wildly barking up the wrong tree! :D
 
I guess I spoke too soon or didn't test/play it enough!?

I noticed one of the sound effects would stop working after a few games. So I replaced a few old caps and such on the soundboard. First impression is it's fixed that.

But that unwanted noise is back. So the grounding wire must have been a red herring.

I've tried so many things, including disconnecting all the connectors to the of for lamps and coils.
Still get the noise.

The station switches still trigger it (providing you've activated that station and the gate is open).

Also in attract the game will appear fine then after a seemingly random period of time the noise will appear, first quietly, then get louder. Sometimes it will stop in under a minute. Other times it seems indefinite (until it drives me mad so I turn it off).

I've tried wiggling cables, shaking the cabinet and unplugging the ribbon from displays and sound board.

It does start as a sort of buzz, which is reminiscent of when you'd plug a jack lead into your guitar. But not as aggressive.

Any ideas? At all?
 
do you have a good pic of the rear of the sound board?

When it makes this sound, should it be actually making a different sound or should it be quiet? You can probably find a youtube video of someone elses game and compare?
 
AlanJ said:
do you have a good pic of the rear of the sound board?

When it makes this sound, should it be actually making a different sound or should it be quiet? You can probably find a youtube video of someone elses game and compare?
Click to expand...

Rare to find any videos of it playing. I tried the Zaccaria pc game and it doesn't appear to make any noise at the same times but it might be an unreliable comparison.

Will get pics of soundboard later today
 
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