(Topic ID: 236253)

System 11 sound problem


By Flynnyfalcon

65 days ago



Topic Stats

  • 30 posts
  • 10 Pinsiders participating
  • Latest reply 60 days ago by Flynnyfalcon
  • Topic is favorited by 2 Pinsiders

You

Linked Games

  • Taxi Williams, 1988

Topic Gallery

There have been 10 images uploaded to this topic. (View topic image gallery).

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#1 65 days ago

Hey Pinside brainstrust,

I have an issue, the music on my Taxi is very quiet compared to the sound effects. It will usually disappear completely, often at the end of the song, not looping to the start of the song again. At the start of a new ball it will mostly start again, attract mode will sometimes have music, sometimes not.

The soundboard looks clean, the cpu board has had some repairs but appears to work ok. I have reseated all cables but now lost as to where to go next. Any ideas what I should do next? Replace Roms?

Thanks

#2 65 days ago

Ive usually had bad capacitors in sound section cause this.

#3 64 days ago
Quoted from pinballplusMN:

Ive usually had bad capacitors in sound section cause this.

Thanks PPMN, any others agree with this prognosis?

#4 64 days ago

Replaced all the caps on the sound board but still the problem remains.

#5 64 days ago

I had an EATPM that did this very thing. What I found was a bad connection with the EPROM and the socket. I ended up just tweaking the pins on the chip and it solved it.

#6 64 days ago
Quoted from Flynnyfalcon:

the cpu board has had some repairs

Let's see a picture of the board.

#7 64 days ago
Quoted from whthrs166:

I had an EATPM that did this very thing. What I found was a bad connection with the EPROM and the socket. I ended up just tweaking the pins on the chip and it solved it.

So basically just reseated the sound roms?

#8 64 days ago
Quoted from PinballManiac40:

Let's see a picture of the board.

I’ll take a few

#9 64 days ago

That's always the easiest thing to try. Carefully reseat all of the sound roms, and the cable connections. What happens when you run the sound test in diagnostic mode? Did you try adjusting the Volume pot in the cabinet? Try cleaning it with contact cleaner?

#10 64 days ago

i had no speech on my earthshaker recently, reseating the x2 cpu chips on the cpu boards fixed the issue.

#11 63 days ago

I agree with pinball plus, top left corner of mpu, replace the capacitors. Fixed many system 11 games.

#12 63 days ago

So I removed the sound board again, removed the sound roms, gave the legs a clean and firmly placed them back in.

When in test mode, both music and sound are loud and clear. One music clip seems to be missing (?) Express Lane 1, but otherwise appears fine. Though when playing a game, the music is very faint compared to the sound effects. Really odd!!

I took a quick vid of the music/sound effect test sequence.

Pics of boards:

5B245EE9-3356-47E6-9DDE-B6C5E6D67227 (resized).jpeg63055382-7D4D-45C6-A53C-A3AC24ABCBD8 (resized).jpegA68BA273-B560-4D62-8859-FAFA498F5094 (resized).jpegD9ABCC81-C657-4E4A-BBA7-F08BEDCBE63B (resized).jpeg
#13 63 days ago
Quoted from sagejr:

That's always the easiest thing to try. Carefully reseat all of the sound roms, and the cable connections. What happens when you run the sound test in diagnostic mode? Did you try adjusting the Volume pot in the cabinet? Try cleaning it with contact cleaner?

Pot appears to work as per normal. Therefore increasing the volume to achieve good music volume means the sound effects are crazy loud!!

#14 62 days ago
Quoted from lostlumberjacks:

I agree with pinball plus, top left corner of mpu, replace the capacitors. Fixed many system 11 games.

Heading out now to grab some caps for the mpu.

Any thoughts on my vid/pics post?? Anyone?

#15 62 days ago

From the looks of your board, there looks like battery acid repairs were done in the area around J21, where the ribbon cable between the boards connects to the MPU. The music test is intended to test the sound card, but in order to do it properly, it has to be able to communicate through U42 on the MPU board to J21. The video you posted of your sound test, I am pretty sure you are not just missing the one sound, I believe it is playing the wrong sounds in a couple of those tests at well. Perhaps someone who owns a Taxi can confirm which sounds are incorrect.

Regardless, from the pictures you posted, it appears that SRC3 has been replaced. It lies along the communication lines that runs between U42 on the MPU board and J21. If you have a break in one of these lines, your sound board will do funny things like play the incorrect sounds during the music test. You may want to check the continuity on all the traces I have circled in red.
U42 (resized).JPG

edit: You may want to also check all of the connections from J21. The rest pass through SRC1, and there are a couple that come from U41.

#16 61 days ago
Quoted from uncivil_engineer:

From the looks of your board, there looks like battery acid repairs were done in the area around J21, where the ribbon cable between the boards connects to the MPU. The music test is intended to test the sound card, but in order to do it properly, it has to be able to communicate through U42 on the MPU board to J21. The video you posted of your sound test, I am pretty sure you are not just missing the one sound, I believe it is playing the wrong sounds in a couple of those tests at well. Perhaps someone who owns a Taxi can confirm which sounds are incorrect.
Regardless, from the pictures you posted, it appears that SRC3 has been replaced. It lies along the communication lines that runs between U42 on the MPU board and J21. If you have a break in one of these lines, your sound board will do funny things like play the incorrect sounds during the music test. You may want to check the continuity on all the traces I have circled in red.
[quoted image]
edit: You may want to also check all of the connections from J21. The rest pass through SRC1, and there are a couple that come from U41.

Appreciate your time and insight UCE. I’ll check for continuity this eve and report back.

Can anyone comments on the music test vid and it’s accuarcy/inaccuracy?

#17 61 days ago

Hmmm, I think I found the culprit... took the main board off to do some testing found what looks to be corrosion bubbling away at the previous repairs.

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#18 61 days ago

verify continuance between the 8 data lines coming for the 6821 @ U42 (pins 10-17) and the pins 3-10 on the ribbon cable connector, sounds like you are missing at least one, you could test with a logic probe during operation to make sure all 8 lines actually get pulled low when activated but the continuance test is easier and quicker

you may find you need to add another jumper or two if any lines fail

#19 61 days ago
Quoted from creepykenny:

verify continuance between the 8 data lines coming for the 6821 @ U42 (pins 10-17) and the pins 3-10 on the ribbon cable connector, sounds like you are missing at least one, you could test with a logic probe during operation to make sure all 8 lines actually get pulled low when activated but the continuance test is easier and quicker
you may find you need to add another jumper or two if any lines fail

Other than cleaning a connector or two, I've never had to deal with corrosion before. What should I do about this bubbling??

I didn't have time to test continuity this eve, but will do tomorrow.

#20 61 days ago

I don't think that bubbling is corrosion related. Ive seen a lot of older circuit boards do that. I don't believe it will affect the boards operation.

Edit: I assume you are talking about the bubbling in the green finish over the trace lines.

#21 60 days ago
Quoted from Flynnyfalcon:

What should I do about this bubbling??

That is glue to hold the jumpers in place. Not very pretty but it's effective.

#22 60 days ago
Quoted from uncivil_engineer:

I don't think that bubbling is corrosion related. Ive seen a lot of older circuit boards do that. I don't believe it will affect the boards operation.
Edit: I assume you are talking about the bubbling in the green finish over the trace lines.

No, I was talking about the bubbling where the jumpers connect. The lower and upper points look quite discoloured when you zoom in. Again, I’ve never dealt with corrosion so it’s appearance is new to me. Just looks quite crude.

#23 60 days ago
Quoted from Flynnyfalcon:

No, I was talking about the bubbling where the jumpers connect. The lower and upper points look quite discoloured when you zoom in. Again, I’ve never dealt with corrosion so it’s appearance is new to me. Just looks quite crude.

I have to agree with GRUMPY on this one, I am pretty sure that is just glue.

#24 60 days ago
Quoted from uncivil_engineer:

I have to agree with GRUMPY on this one, I am pretty sure that is just glue.

Mmm ok, if that is the case then that is good news then.

#25 60 days ago

Extra pics

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#26 60 days ago

Probably more the colour which sparked my concern.

I agree it is a glue type substance, but could it be corrosion building up underneath?

#27 60 days ago

Typically corrosion builds up on the battery side of the board. That glue looks like it was placed there after the repairs were made.

#28 60 days ago
Quoted from uncivil_engineer:

Typically corrosion builds up on the battery side of the board. That glue looks like it was placed there after the repairs were made.

That’s super helpful information. Appreciate it UCE

#29 60 days ago

not unusual to find breaks cause by corrosion under the resistor networks - tough to see but easy to find

i use clear nail polish to secure the kynar wires used for repairing so the glue is fine or whatever that is

#30 60 days ago

So looks like I’ve hit a moderate hickup. The board looks to have been coated post repairs in a lacquer or something similar which is preventing me from accurately testing continuity etc. Test results are flaky so any certainty is lost I think it’s either pro help or Rottendog

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