When I boot it up everything comes on find but many/all of the musical sounds are short and sound like digital chirps instead of the normal tune. However, many/most other game sounds are normal.

Places I see the sound issue:
- Power on tune
- Grotto tune
- End of ball bonus tune

Example good sounds from a random review video below.

Note the smooth tune and elongated tones:

Sounds I recorded below.

Note target and rollover sounds are fine but grotto and end of turn is weird:

Note the weird version of the startup tune after the target reset:

I've looked at Pinwiki and around here. I haven't seen anything specific but do see the default recommendation is to replace the caps which hasn't been done. Would bad/old caps cause this issue for some sounds and not others? Any suggestions on where to look? I see no obvious damage on the AS-2518-32 board.

Thanks I headed to bed so will do that tomorrow. I had read to not mess with that so I will do some research and report back.

Thanks for your help everyone. Sustain didn't help. It actually did make the sounds sound how they should for the most part except there is always a background sound as soon as I start it or constantly in sound test mode. I don't think it's the sustain since the knob hasn't been moved, at least on purpose.

I would think a component failure is more likely. I've tried the test points on the sound board and they all look good.

I can't believe I somehow missed this delightful book:

Bally Electronic Pinball Games Repair Procedures
Module & Component Replacement
F.O. 560-1

Walking through the repair procedures I fail at:

Section II: Frequency Generation Associated Failures
Symptom II: No sound of incorrect tone sequence. (Frequency division failure)
Step B: U11 Defective

U11 pin 9 has +2 VDC, but pin 11 has 0 VDC where it should have +2 VDC.

I'm going to look into troubleshoot the chip itself more and probably order a replacement. Anyone familiar with this board have an opinion if this could explain my symptoms?

I replaced U11, all caps, and both pots with no resolution. I'll re-visit F.O. 560-1 and see if Step II.II.B passes.

Thanks! I had already ordered some parts before I saw your post. This will be my next step!

The saga continues... As I said I replaced U11 with a brand new 74LS93 ( https://www.digikey.com/product-detail/en/texas-instruments/SN74LS93N/296-3750-5-ND/377783 ) and it's still not working quite right. I busted out my 8-lead logic analyzer and checked as much as I could and I still think U11 is defective or something.

Per Tuukka I checked Sound Board J1, Solenoid J4, and even MPU J1 and everything pulses correctly and I don't see any bad solder joints. I did reflow Sound Board J1 just in case.

EDIT: When I went to remove the logic probe lead from the chip pin it came off very easily and turns out wasn't maintaining good contact. U11 Pin 11 is working properly. Leaving the below here for reference for anyone else looking to do this troubleshooting.

Quench 's awesome post in this thread ( https://pinside.com/pinball/forum/topic/bally-sound-board-as-2518-32-constant-tone#post-4363880 ) has served as a great troubleshooting step. Quench , I would love your input on below.

Quenchs Diagram

As far as I can tell signals are all working into U2 (Red):

U2 Inputs - Quench Post Red

And out of U2 into U1 (Blue):

U2 Outputs - Quench Post Blue

And out of U1 into U3 (Pink):

U3 Inputs - Quench Post Pink

And out of U3 (Green):

U3 Outputs - Quench Post Green

--- BELOW IS INCORRECT, WAS MISSING LOGIC PROBE LEAD ---

Which leads me back to U11... I never get an output on U11 Pin 11 in sound test mode, or even in gameplay mode with all kinds of pop bumpers, roll overs, slingshots going off. See below (zoomed way out, then way in):

U11 Relevant Pins All
U11 Relevant Pins Zoomed

U11 is a brand new chip. I have a second one which I may swap again but I feel like something else is wrong here.

This lovely german page ( http://www.pinball4you.ch/okaegi/rep_soundold.html ) points to U11 again as well. 74LS93 is recommended as a replacement for the 86L93 which comes with the game, and all the pinouts appear to match so I don't think it's a chip compatibility issue. I'll probably pull the sound board out of the backbox and check all the pins again.

Anyone have any ideas what would explain this?

--- ABOVE IS INCORRECT, WAS MISSING LOGIC PROBE LEAD ---

I'll continue working through the troubleshooting guide...

The saga continues... I busted out my 8-lead logic analyzer and checked as much as I could.

Per Tuukka I checked Sound Board J1, Solenoid J4, and even MPU J1 and everything pulses correctly and I don't see any bad solder joints. I did reflow Sound Board J1 just in case.

Quench 's awesome post in this thread ( https://pinside.com/pinball/forum/topic/bally-sound-board-as-2518-32-constant-tone#post-4363880 ) has served as a great troubleshooting step. Quench , I would love your input on below.

Quench's Diagram

As far as I can tell signals are all working into U2 (Diagram Red):

U2 Inputs - Quench Post Red

And out of U2 into U1 (Diagram Blue):

U2 Outputs - Quench Post Blue

And out of U1 into U3 (Diagram Pink):

U3 Inputs - Quench Post Pink

And out of U3 (Diagram Green):

U3 Outputs - Quench Post Green

And U4 and U5...

U4 and U5 AllU4 and U5 Zoomed

And U11...

U11 AllU11 Zoomed

I lose the ability to use the Logic Analyzer when I get near R3/R4/R5 due to the voltage drop but a multimeter shows slight activity during sounds on all sides of the resistors.

From all the troubleshooting I'm reading as long as you're getting pulses through these pins you should be good. I'm not sure how to check if they're the correct pulses and I don't think that's even possible without a TON of effort.

Anyone have any suggestions on where to look next? Going to keep looking at various troubleshooting guides I've found...

I think I may have found the culprit. It's 1am so I'll troubleshoot more tomorrow but at first glance I think CR1 may be bad. This thread ( https://pinside.com/pinball/forum/topic/bally-kiss-sound-board-problem#post-4920481 ) pointed me in the right direction.

CR-1 I'm getting 0.600 one direction and 1.578 the other direction.
CR-2 I'm getting 0.596 one direction and OL (0) the other direction.

The issue is the same, but maybe I can sum it up better. I can make the single tone sounds sound correct by turning up the sustain but then there is a constant tone in the background. At this point the choice is simply between:
- Short tone sounds (more like chirps) with no background noise
- Proper tone sounds with constant background tone

Here is a 2min video I just took illustrating the current issue and my understanding of how it SHOULD sound:

Here is a close up of the sound board:

1978 Bally Sound Board

Edit: Here is a video I found on youtube which shows to how the sounds should sound (though in this video they sound a little "tinny" to me). Startup at 2:41 and sound test at 22:35.

Yes, I missed C6 when ordering parts off Digikey last week. Looking at the schematic it could be culprit. I do have two extra new 1uf from that previous order (C8/C11). I think I'll add those two 1uf caps in parallel as a troubleshooting step. Sound like a good idea?

In the mean time I've just ordered some new C6 (2.2uf 50V), and because I'd like to order others incase I need them, I ordered some CR4 (Zener), CR1/CR2, and R36 (5W 75 Ohm).

It works!!! I replaced C6 (stock 2uf 25V) with 2 extras (in parallel) from C8/C11 I had (1uf 50V) to make a single 2uf 50V capacitor. I discovered my Fluke 175 DMM had a capacitor test mode I never noticed and sure enough the original C6 showed OL both on and off the board.

I'm frustrated that I forgot one capacitor out of the 4 and it happened to be the one causing issues. I knew it was fixed immediately when I turned on the machine because I turned it off with sustain set to have no undertone, and when I switched the machine on I heard a faint tone. A quick sustain adjustment later and the tune is perfect!

So I guess all my toubleshooting and logic analyzer work was a waste and if I had just done the cap replacement properly this would have been solved a week ago.

Thanks again for everyone's expertise. I'll leave the logic screenshots and this thread around incase anyone else needs a reference when troubleshooting. Though I just placed an order at Digikey I'll replace my makeshift 2uf with a proper 2.2uf 50V when it arrives and at least now I have some replacement pieces.

I've learned an awful lot troubleshooting this board and if anyone needs help in the future add me to the thread or PM me and I'll try to contribute.

C6 Makeshift Replacement