(Topic ID: 239636)

Bally KISS sound board problem


By igo4rams

85 days ago



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  • 39 posts
  • 7 Pinsiders participating
  • Latest reply 81 days ago by igo4rams
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#1 85 days ago

I was hoping someone could help me locate the problem with my 1979 Bally Kiss sound board. I will buy a new board if I can't fix it but would like to try and fix it first. I do not have a scope. But if someone could tell me what area the problem could be, I will replace that/those parts and see if it works.

The board works for the most part. I replaced all the large caps and re soldered the connector pins. The sounds seem to run a little fast and at the start of ball play and at the end of the game the last note of the tune never shuts off. The last note just plays on and on and on. That is until another tone is played by hitting the start button or a switch or the game is turned off.

Thanks for you time

#2 85 days ago

Sounds like the sustain circuitry on the sound board isn't working properly.

Check that the sustain pot isn't dirty - rotate it full swing either way a few times then put it back where it was.

The 555 timer chip at U7 creates the sustain timing. It's output (pin 3) should pulse to 11 volts for 5 milliseconds when tones are played then go to zero volts. So measure the voltage at pin 3 of U7 to make sure its around zero volts when no sounds should be playing.
This 555 output then goes to the sustain mute circuitry so tones smoothly and quickly decay - the sustain pot is in this circuit if you're looking at the schematics.

#3 85 days ago
Quoted from Quench:

Sounds like the sustain circuitry on the sound board isn't working properly.
Check that the sustain pot isn't dirty - rotate it full swing either way a few times then put it back where it was.
The 555 timer chip at U7 creates the sustain timing. It's output (pin 3) should pulse to 11 volts for 5 milliseconds when tones are played then go to zero volts. So measure the voltage at pin 3 of U7 to make sure its around zero volts when no sounds should be playing.
This 555 output then goes to the sustain mute circuitry so tones smoothly and quickly decay - the sustain pot is in this circuit if you're looking at the schematics.

I did move the sustain pot and it acts like a volume pot. The sound moves up and down when I turn it up and down. I will check the pin 3 of U7 as you say. If I get voltage there should I replace the U7 chip?

#4 85 days ago
Quoted from igo4rams:

I did move the sustain pot and it acts like a volume pot. The sound moves up and down when I turn it up and down.

Sounds like the problem is U7 and/or the circuitry controlling it.

Quoted from igo4rams:

I will check the pin 3 of U7 as you say. If I get voltage there should I replace the U7 chip?

Not yet, you need to determine if the U7 chip is just doing what its told. So if you measure around 11 volts on its pin 3 output then you'll need to measure its input trigger pin which is pin 2.
A high to low to high pulse on pin 2 will trigger the U7 timer chip output to go high for 5ms. If pin 2 is stuck low, the timer will never time out.

If you measure close to 12 volts on pin 2, then closely inspect resistor R21 and capacitor C16 and their soldering. If ok, then replace U7.

If you measure close to zero volts on pin 2 of U7 then the problem may be around transistor Q2. The transistor is being switched on for some reason and you need to find out why.

BTW, what voltage do you measure on test point TP3 of the sound board?

#5 85 days ago
Quoted from Quench:

Sounds like the problem is U7 and/or the circuitry controlling it.

Not yet, you need to determine if the U7 chip is just doing what its told. So if you measure around 11 volts on its pin 3 output then you'll need to measure its input trigger pin which is pin 2.
A high to low to high pulse on pin 2 will trigger the U7 timer chip output to go high for 5ms. If pin 2 is stuck low, the timer will never time out.
If you measure close to 12 volts on pin 2, then closely inspect resistor R21 and capacitor C16 and their soldering. If ok, then replace U7.
If you measure close to zero volts on pin 2 of U7 then the problem may be around transistor Q2. The transistor is being switched on for some reason and you need to find out why.
BTW, what voltage do you measure on test point TP3 of the sound board?

Good info, Thanks. What I found:

TP3 12.8 volts DC
U7 pin 2 12.9 volts DC
U7 pin 3 .0 to .34 volts DC
R-21 115k good
C16 could not test can't find my cap tester at this time

all solder look good U7 legs look like they have been hot?

Looks like replacing U7 is my best option? Next, order one and a socket. I will post update later.

#6 85 days ago
Quoted from igo4rams:

U7 pin 3 .0 to .34 volts DC

Your voltages around U7 look normal, 11 volts on pin 3 of U7 would have pointed to a problem around U7 but you measured near zero volts which is ok. Your issue looks further downstream. Do diodes CR1 and CR2 test ok?

Post some clear pictures of this sound board front and back.

Was this sound board ever working in your possession or did you purchase the machine with it malfunctioning?

#7 85 days ago
Quoted from Quench:

Your voltages around U7 look normal, 11 volts on pin 3 of U7 would have pointed to a problem around U7 but you measured near zero volts which is ok. Your issue looks further downstream. Do diodes CR1 and CR2 test ok?
Post some clear pictures of this sound board front and back.
Was this sound board ever working in your possession or did you purchase the machine with it malfunctioning?

CR-1 .755 and 0 the other way
CR-2 .954 and 0 the other way

Hope these pics help.

CAEE49EF-06A6-44BA-957D-EFEE3443926F (resized).jpeg320010D3-0EFC-47E2-991D-064303E60F53 (resized).jpeg
#8 85 days ago
Quoted from igo4rams:

CR-1 .755 and 0 the other way
CR-2 .954 and 0 the other way

These diode readings are with your meter set to diode mode and the machine is off right? When you say "0" does that mean no change in meter reading or is the meter telling you it's a short circuit?

Typical forward voltage drop across diodes is around 0.6 measured one way (black meter lead on the banded side of the diodes). Your readings look high especially CR2. If you have spare 1N4148 diodes replace them, if not you can try 1N4004 diodes for test.

#9 85 days ago
Quoted from Quench:

These diode readings are with your meter set to diode mode and the machine is off right? When you say "0" does that mean no change in meter reading or is the meter telling you it's a short circuit?
Typical forward voltage drop across diodes is around 0.6 measured one way (black meter lead on the banded side of the diodes). Your readings look high especially CR2. If you have spare 1N4148 diodes replace them, if not you can try 1N4004 diodes for test.

I should have said, no reading the other way. Yes meter on diode. I know I have some 1N4004s not sure if I have any 1N4148s

#10 85 days ago

Replaced both CR1 and CR2 with 1n4148s and no change. I have .71 and .72 readings now. The last note/tone on just ball start and end of last ball just keeps playing on and on.

#11 84 days ago

If I remember right , U8 causes the sustain forever issue.

#12 84 days ago
Quoted from jj44114:

If I remember right , U8 causes the sustain forever issue.

I know I will have to order a U8 chip. Thanks for the info

#13 84 days ago

Check the voltage on the bottom of resistor R7, it should be near zero volts.
It looks ok but also check that resistor R10 measures 150k. It primarily discharges capacitor C6 to create the sustain decay curve.
As jj44114 mentioned you can replace U8 which mixes the sustain mute with the audio tones. Note, U8 is the same as U1 so if you have IC sockets you could try swapping them. If behavior substantially changes you know that 4049 chip was bad.

#14 84 days ago

No sockets yet, so I can't change U1 with U8.
Got 50k on R10 not 150k
Got .35 volts on R7 bottom with no sound and up to 6.3 with sounds

Do I have a bad R10?

#15 84 days ago
Quoted from igo4rams:

Got 50k on R10 not 150k

I measure around 128k ohms with the R10 in circuit on one of my boards. But a low value for R10 should make the tones shut off sooner rather than sustaining forever. Anyway unsolder one of R10 legs and remeasure it so its not in circuit.

#16 84 days ago

Just removed R10 from board and it is good 150k?

#17 84 days ago

I am no expert but I had the same problem and a friend linked it to my aftermarket driver board.Put in original Bally board problem fixed.

#18 84 days ago
Quoted from whizz:

I am no expert but I had the same problem and a friend linked it to my aftermarket driver board.Put in original Bally board problem fixed.

I have the original driver board. So that must not be it.

#19 84 days ago

Just a thought.Mine drove me crazy.I had to get expert help.

#20 84 days ago
Quoted from whizz:

Just a thought.Mine drove me crazy.I had to get expert help.

Thanks for the thoughts. I will work on it a while, if I can't win I will buy a new board.

#21 84 days ago
Quoted from igo4rams:

Just removed R10 from board and it is good 150k?

I just measured R10 in circuit on three other boards and they read 130k ohms.. Something in that circuit might be suss.
Anyway change U8 and see how it goes. Note the original U8 chip is a 4049U (U for unbuffered). I can't remember whether its critical for it to be the unbuffered version of the chip or not. i.e. you can buy a 4049B (buffered) or 4049UB (unbuffered). Get the unbuffered to be sure. Don't worry about any extra letters in the part number - they're usually manufacturer specific.

#22 84 days ago
Quoted from Quench:

I just measured R10 in circuit on three other boards and they read 130k ohms.. Something in that circuit might be suss.
Anyway change U8 and see how it goes. Note the original U8 chip is a 4049U (U for unbuffered). I can't remember whether its critical for it to be the unbuffered version of the chip or not. i.e. you can buy a 4049B (buffered) or 4049UB (unbuffered). Get the unbuffered to be sure. Don't worry about any extra letters in the part number - they're usually manufacturer specific.

4049B works ok as the lower 4049 chip but it changes how the tones sound slightly. The component list I think actually calls for 4049B, but all the boards seem to have been built with MC14049UBE

#23 84 days ago

Update; changed U8 and no change, still plays last note on and on. Not sure if this means anything but it doesn’t play the last note on and on when the game is turned on just first ball and last ball drain? I am using a after market mpu.

AE108EA4-FE73-441B-BD52-459B51DC47E0 (resized).jpeg
#24 84 days ago

I switch the mpu out and no change. Also changed dip switch 8 and 32 and no real change. Did notice most tunes play last note on and on.

#25 84 days ago

I am pretty sure I have encountered your symptoms (sustain issues with high pitch tones sustaining forever) but I am to unable to remember the cause.... back of my head says something with the 555 timer chip or maybe even the 4526 chips, but I could be remembering wrong.

Oliver wrote up a nice repair guide if you can follow through to the end it should fix most of these sound boards. Put the game in sound test and check points he talks about.

http://www.pinball4you.ch/okaegi/rep_soundold.html

#26 83 days ago

olivers repair guide is spot on, used it to repair a bally 32 sound board this morning, a great resource

#27 83 days ago
Quoted from igo4rams:

...still plays last note on and on. Not sure if this means anything but it doesn’t play the last note on and on when the game is turned on just first ball and last ball drain?

There are two ways the sound board goes silent.
One, certain sounds/patterns finish up by selecting a high frequency 'tone' way beyond what humans can hear. You can see this with an oscilloscope.
Two, the sustain (really it's a decay function, not sustain) gently mutes the current audible tone being played.

So the reason the start game and end game tunes play forever is those tune patterns don't finish with the inaudible high frequency tone. And your decay circuit is malfunctioning meaning the last tone of those patterns is never muted.

What happens to normal sounds and the start/end game tunes if you disconnect one leg of resistor R11 from the circuit?

#28 82 days ago
Quoted from Quench:

There are two ways the sound board goes silent.
One, certain sounds/patterns finish up by selecting a high frequency 'tone' way beyond what humans can hear. You can see this with an oscilloscope.
Two, the sustain (really it's a decay function, not sustain) gently mutes the current audible tone being played.
So the reason the start game and end game tunes play forever is those tune patterns don't finish with the inaudible high frequency tone. And your decay circuit is malfunctioning meaning the last tone of those patterns is never muted.
What happens to normal sounds and the start/end game tunes if you disconnect one leg of resistor R11 from the circuit?

I removed one leg on R11, checked R11 and it was good at 1M. Powered up game and no change to sounds, still plays last note on and on. Are you thinking change U7 the 555?

#29 82 days ago

did you check the resistance on the sustain pot, both the wiper and the base?

#30 82 days ago
Quoted from igo4rams:

Are you thinking change U7 the 555?

With R11 disconnected, you've isolated U7 off the sustain circuit so U7 is not your problem.

It sounds like the RT2 sustain pot has lost connection to ground which results in the sustain circuit being unable to mute.

Reconnect resistor R11.
With the game powered on and the last note of the start or end game tune playing, measure the voltage on the lower leg of resistor R12 which is to the left of the RT2 pot. With the RT2 pot adjusted fully clockwise you should measure 12 volts on the lower leg of R12. As you adjust the pot anticlockwise it should end up at zero volts on R12. Is this what you are seeing?

BTW the picture above of your sound board has RT2 set fully clockwise which will play notes on and on. The sweet spot is generally around 11pm to 12pm on the dial.

#31 81 days ago
Quoted from Quench:

With R11 disconnected, you've isolated U7 off the sustain circuit so U7 is not your problem.
It sounds like the RT2 sustain pot has lost connection to ground which results in the sustain circuit being unable to mute.
Reconnect resistor R11.
With the game powered on and the last note of the start or end game tune playing, measure the voltage on the lower leg of resistor R12 which is to the left of the RT2 pot. With the RT2 pot adjusted fully clockwise you should measure 12 volts on the lower leg of R12. As you adjust the pot anticlockwise it should end up at zero volts on R12. Is this what you are seeing?
BTW the picture above of your sound board has RT2 set fully clockwise which will play notes on and on. The sweet spot is generally around 11pm to 12pm on the dial.

Thanks so much. I was sure I moved that pot a few times and did not notice any change. The sound works like it should now. Just wish it could be a little louder. I moved the volume pot and it is working but not as loud as you would think it should be. I did replace the speaker, here is a pic. Could that be the problem? I matched it up with the old one.

IMG_1583 (resized).jpg
#32 81 days ago

Hooked up another 8 ohm speaker and sound was lower. Back to the one in the pic. Sound is ok just not high as I would like. Maybe that is normal? You can hear the sound ok but if there were music or other games playing, well.

#33 81 days ago

low but adjustable volume is typically a bad LM741.

#34 81 days ago

I don’t know if the Kiss sound board is the same but on EBD there are 2 small dial resistors that control volume before the door volume. One is for speech and the other for sound effects. I turned those up and then adjust on the door.

Dave

#35 81 days ago
Quoted from igo4rams:

Thanks so much. I was sure I moved that pot a few times and did not notice any change.

Earlier in the thread you said the following, so maybe changing U8 fixed the issue but you didn't know it:

Quoted from igo4rams:

I did move the sustain pot and it acts like a volume pot. The sound moves up and down when I turn it up and down.

.

Quoted from Calipindave:

I don’t know if the Kiss sound board is the same but on EBD

They're totally different boards.

#36 81 days ago
Quoted from Quench:

Earlier in the thread you said the following, so maybe changing U8 fixed the issue but you didn't know it:

.

They're totally different boards.

Thanks Quench. Wasn’t certain.
D

#37 81 days ago

Earlier in the thread you said the following, so maybe changing U8 fixed the issue but you didn't know it:

I think your right.

So are you with barakandI and I should change the LM741 ? Is there a way to test it?

#38 81 days ago
Quoted from igo4rams:

So are you with barakandI and I should change the LM741 ? Is there a way to test it?

I haven't had to change any LM741 on these boards, but I would first do what barakandl mentions in the below post. Ballys original design of connecting the + input of the LM741 to ground was a bad idea. The input used as a reference (pin 3 in this design) should be connected to half the power-supply voltage which Bally corrected on later boards and what the mod does. This should give a better amplification range.

https://pinside.com/pinball/forum/topic/playboy-as-2518-32-sound-probs#post-3159929

[Edit] I just noticed your sound board already implements the mod. Change the LM741 and see how you go.

#39 81 days ago
Quoted from Quench:

I haven't had to change any LM741 on these boards, but I would first do what barakandl mentions in the below post. Ballys original design of connecting the + input of the LM741 to ground was a bad idea. The input used as a reference (pin 3 in this design) should be connected to half the power-supply voltage which Bally corrected on later boards and what the mod does. This should give a better amplification range.
https://pinside.com/pinball/forum/topic/playboy-as-2518-32-sound-probs#post-3159929

[Edit] I just noticed your sound board already implements the mod. Change the LM741 and see how you go.

LM741 is in the mail, I will post what happens after I change it. Thanks everyone for your help

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