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(Topic ID: 276379)

Stern SB-100 Sound Problems


By troxel

51 days ago



Topic Stats

  • 39 posts
  • 4 Pinsiders participating
  • Latest reply 35 days ago by Quench
  • Topic is favorited by 6 Pinsiders

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There have been 13 images uploaded to this topic. (View topic image gallery).

SB100_U6_R68.jpg
74107_TruthTable.gif
SB100_SW23.gif
SB100_Lectronamo1_Shorts.jpg
IMG_7521.jpg
IMG_7519.jpg
IMG_7518.jpg
IMG_7517.jpg
IMG_7516.jpg
IMG_7515.jpg
IMG_7514.jpg
IMG_7513.jpg
Pinside_NoScaling.png

#1 51 days ago

Stern SB-100 (Lectronamo) -- I am only getting sounds 2 and 4 when I test the sound in test mode. (Should it be 1-4 or 1-6 in the test)?

If I hit a 10 point switch, it will only make noises on every other hit. The same is true for 100 points.

Board has been recapped, new cables, speaker and pot tested fine along with the header pins re-soldered.
U6 pin pin 6 is low. U7 outputs are activating when a switch is hit, and replaced U18 (LM324).

Not sure how to troubleshoot this and would gladly take any advice. Thanks!

#2 51 days ago
Quoted from troxel:

I am only getting sounds 2 and 4 when I test the sound in test mode. (Should it be 1-4 or 1-6 in the test)?

It should be 1-6:
#01 - 10 point sound
#02 - 100 point sound
#03 - 1000 point sound
#04 - 10000 point sound
#05 - add bonus sound
#06 - pop bumper sound

Have you got a logic probe?

The outputs on U3 are the point sound tones enables
The outputs on U4 are the add bonus and pop bumper sound enables/triggers
The point sound frequencies are generated by the LM324 at U17 - if you look at the outputs of this chip on the schematics, they should all measure around 2.5 volts meaning they're oscillating.

#3 51 days ago

Thanks quench! I forgot to mention that all the test points tested fine.

I do have a logic probe. I'll measure the outputs on U17.

Anything else to check?

#4 51 days ago
Quoted from troxel:

I do have a logic probe. I'll measure the outputs on U17.

The LM324's have four op-amps in them. Only three in U17 are used. They're a common failure on these boards. Output pins 7, 8 and 14 should all be oscillating (pulsing). That's the first place to start.
Once you confirm they're working, check the frequency divider outputs on pins 1 and 13 of U8 and pins 1 and 13 of U9. These should all be oscillating (pulsing).

There's lots of things to check but start with these common chip failure tests.

Once you confirm these are working you'll have to go upstream and check U3 and U4.

#5 50 days ago

Had a couple minutes this morning to look at this, and the outputs on U17 were all HIGH. Replaced U17 with no change.

#6 50 days ago

Can you please post clear high res pictures front and back of this board?

#7 50 days ago

Thanks again for the help!
IMG_7513.jpgIMG_7514.jpgIMG_7515.jpgIMG_7516.jpgIMG_7517.jpgIMG_7518.jpgIMG_7519.jpg

IMG_7521.jpg

#8 50 days ago
Quoted from troxel:

Had a couple minutes this morning to look at this, and the outputs on U17 were all HIGH. Replaced U17 with no change.

Is U17 getting a ground connection? (U17 pin 11 is ground, U17 pin 4 is +5V) - measure the DC voltage across those two pins.
And can you measure the output pin voltages with your multi-meter on U17 pins 7, 8 and 14. They should all measure around 2.5 volts.

Pinside resized the pictures when you uploaded them. Can you re-edit your previous post and upload the pictures again but without scaling so I can see more detail? Cheers.

Pinside_NoScaling.png

#9 50 days ago

Changed the images size and will check voltages this evening.

#10 50 days ago

I had this in my Trident.
I landed up rebuilding the board almost completely.
It was bullet proof after that.

#11 50 days ago

U17 checks out fine. +5 volts is present and getting about 2.5 volts on the output pins.

#12 50 days ago
Quoted from troxel:

Changed the images size and will check voltages this evening.

Cheers, those pics are much better
Check the solder whiskers circled on the picture below in yellow aren't causing a short to the adjacent trace:

Quoted from troxel:

U17 checks out fine. +5 volts is present and getting about 2.5 volts on the output pins.

The 2.5V on the U17 outputs generally indicates the tone frequency generators are oscillating. Question is why the your logic probe was just picking them up as high. Need to resolve this otherwise the logic probe won't help us. Can you post a picture of the logic probe?

BTW, how do you have dip switch #23 set? It affects which parts of the sound board are used. If it's set to Electronic Chimes (OFF) then many more parts of the board need to be functional. For the moment, please put this switch #23 ON.

SB100_SW23.gif

SB100_Lectronamo1_Shorts.jpg

#13 50 days ago
Quoted from Quench:

Cheers, those pics are much better
Check the solder whiskers circled on the picture below in yellow aren't causing a short to the adjacent trace:

There was no bridge on the points you circled.

Quoted from Quench:

The 2.5V on the U17 outputs generally indicates the tone frequency generators are oscillating. Question is why the your logic probe was just picking them up as high. Need to resolve this otherwise the logic probe won't help us. Can you post a picture of the logic probe?

I have a built in logic probe function on my meter that didn't show it pulsing. I switched to my Elenco and the outputs of U17, U8, and U9 were all pulsing.

Quoted from Quench:

BTW, how do you have dip switch #23 set?

#23 is set to on

#14 50 days ago

Hook up your Elenco logic probe. At the sound board, you should see the following activity in solenoid test mode at each test:

#01 - U3 pin 9 should pulse high (activate 10 point sound)
#02 - U3 pin 10 should pulse high (activate 100 point sound)
#03 - U3 pin 15 should pulse high (activate 1,000 point sound)
#04 - U3 pin 16 should pulse high (activate 10,000 point sound)
#05 - U4 pin 9 should pulse high (activate Add Bonus sound)
#06 - U4 pin 10 should pulse high (activate Pop Bumper chirp sound)

It's probably easier if you take the playfield glass off and start a game. Tap a 10 point score switch and watch if pin 9 of U3 pulses high. Ditto for other point scores and their respective U3/U4 activity.

Let us know if you get the correct activity or not.

#15 49 days ago
Quoted from Quench:

#01 - U3 pin 9 should pulse high (activate 10 point sound)
#02 - U3 pin 10 should pulse high (activate 100 point sound)
#03 - U3 pin 15 should pulse high (activate 1,000 point sound)
#04 - U3 pin 16 should pulse high (activate 10,000 point sound)
#05 - U4 pin 9 should pulse high (activate Add Bonus sound)
#06 - U4 pin 10 should pulse high (activate Pop Bumper chirp sound)

All of these did transition to high during solenoid test.

One odd thing was that I had some of the odd number sounds work during solenoid test and another time just sounds 2 and 4 were making noises.

#16 49 days ago

BTW, it's not a problem with your volume control being dirty or loose connections on the speaker?
When you turn the volume up do you get any speaker hum (indicating the amplifier and volume attenuator circuits are working)?
If you wiggle the connectors on the sound board, does anything audio wise happen?

Downstream from the U3/U4 tests you just did:

#01 - 10 point sound at U7:
......... pin 1 should always be pulsing (oscillating),
......... pin 2 should pulse high when 10 point sound activates, this then allows:
......... pin 3 to pulse (oscillate) when the 10 point sound is active

#02 - 100 point sound at U7:
......... pin 4 should always be pulsing (oscillating),
......... pin 5 should pulse high when 100 point sound activates, this then allows:
......... pin 6 to pulse (oscillate) when the 100 point sound is active

#03 - 1,000 point sound at U7:
......... pin 10 should always be pulsing (oscillating),
......... pin 9 should pulse high when 1,000 point sound activates, this then allows:
......... pin 8 to pulse (oscillate) when the 1,000 point sound is active

#04 - 10,000 point sound at U7:
......... pin 13 should always be pulsing (oscillating),
......... pin 12 should pulse high when 10,000 point sound activates, this then allows:
......... pin 11 to pulse (oscillate) when the 10,000 point sound is active

#05 - Add Bonus sound at U6:
......... pin 13 should pulse (oscillate) when the Add Bonus sound activates, this then allows:
......... pin 3 to pulse (oscillate) when the Add Bonus sound is active

#06 - Pop Bumper chirp sound at U18:
......... pin 1 should pulse (oscillate) when the Pop Bumper chirp sound is active
......... pin 7 should pulse (oscillate) when the Pop Bumper chirp sound is active (from memory)

#17 49 days ago

Thanks again for the help. Pot and speakers test fine. If I adjust the pot the speaker will hum. Switched out the speaker and still no change.

Something goofy is going on with this. I tested the sound again with solenoid test and sounds 1, 3, 5, 6 worked. Turned it off and retested and only sounds 2 and 4 were working.

I have re-soldered the header pins, new 32-pin connector, and the MPU is new. Re-pinned J3 connector. I wiggled the connectors and still no change.

#18 49 days ago

Get the sound board back in failure mode and check activity with your logic probe at the points listed in my previous post #16
We need to try and isolate what is/isn't still working in failure mode.

#19 48 days ago

I can get all the signals in post 16 on my logic probe. While the logic probe shows the correct signals, sounds are still missing.

Here’s a bad video showing me test the 10 point sounds on U7. The sound only plays on every other hit. It will beep on the first hit and just hum on the second hit. The humming continues until the switch is hit.

#20 48 days ago

Hmm, weird.
With the 10 point switch test, can you do/comment on the following:

Does the oscillating input on pin 1 of U7 change between 10 point switch hits (it shouldn't).

Probe pin 6 of U6 while hitting the 10 point switch. Pin 6 should always stay high but wondering if it's changing.

Probe pin 9 of U5 while hitting the 10 point switch. Does it pulse high?

What happens on pin 14 of U15 when nothings happening, and then when you hit a 10 point switch?

What happens on pin 8 of U16 when nothings happening, and then when you hit a 10 point switch?

What happens on pin 1 of U16 when nothings happening, and then when you hit a 10 point switch?

Have you got an oscilloscope by any chance?

#21 47 days ago

Thanks again for the help. I think you are getting close .

Quoted from Quench:

Does the oscillating input on pin 1 of U7 change between 10 point switch hits (it shouldn't).

No, it oscillates like it should.

Quoted from Quench:

Probe pin 6 of U6 while hitting the 10 point switch. Pin 6 should always stay high but wondering if it's changing.

***There is a discrepancy here. It latches between low and high.

Quoted from Quench:

Probe pin 9 of U5 while hitting the 10 point switch. Does it pulse high?

It always stays high.

Quoted from Quench:

What happens on pin 14 of U15 when nothings happening, and then when you hit a 10 point switch?

Both cases show high on the probe.

Quoted from Quench:

What happens on pin 8 of U16 when nothings happening, and then when you hit a 10 point switch?

Both cases show low on the probe.

Quoted from Quench:

What happens on pin 1 of U16 when nothings happening, and then when you hit a 10 point switch?

Both cases show low on the probe.

Quoted from Quench:

Have you got an oscilloscope by any chance?

Yes, I do. I don't use it much but have one.

#22 47 days ago
Quoted from troxel:

***There is a discrepancy here. It latches between low and high.

Interesting.
So when you hit the 10 point switch and you just get a hum, what logic state do you get on pin 6 of U6?
And does pin 6 of U6 toggle to the opposite state when you hit the 10 point switch and it actually plays the tone as it should?

#23 47 days ago

I get the 10 point sound when pin 6 transitions from low to high. If it goes from high to low then I get the hum. This pattern repeats as I hit the 10-point switch.

#24 47 days ago

Ok.
That part of U6 is there to mute the amplifier chip on power up so you don't get any screech/pops from the speaker. But after power up, pin 6 should stay high and not mute the amplifier again.

Can you probe the following pins on U6 while hitting the 10 point score and let us know what happens when it hums and when the tone plays properly:

U6 pin 5 =
U6 pin 8 =
U6 pin 9 =
U6 pin 10 =
U6 pin 11 =

#25 46 days ago
Quoted from Quench:

Can you probe the following pins on U6 while hitting the 10 point score and let us know what happens when it hums and when the tone plays properly:

Sound triggers when transitions from low to high. Hums when going from high to low.

High for both instances.

Low for both instances.

High for both instances.

Low for both instances.

#26 46 days ago
Quoted from troxel:

U6 pin 9 = Low for both instances.

This one must be a typo or misread. U6 pin 9 should pulse high every time the board plays a sound. If it was indeed stuck low, the board would never play anything.

Below is the logical truth table for this U6 chip just probed.
The green row is how it should be operating.
However the operation you're getting is the red row where the outputs are toggling.
The difference between the two rows is the state on pin 11. The board has pin 11 input connected low (ground), but the chip is seeing it as high. This suggests that pin may have internally gone open circuit so it's looking like the U6 "74107" chip is suspect.

Can you please try the following: Find resistor R68 next to U6, unsolder one of it's legs and pull that leg out of the board so R68 is disconnected. This should disable the mute circuit. Besides a squelch on power up, does the board now play sounds properly?
.

74107_TruthTable.gif

SB100_U6_R68.jpg

#27 46 days ago

Yes, it was a typo. That's what I get for copying and pasting on my phone. Pin 9 is pulsing when the 10-point switch is hit.

I removed the leg on R68 and the sounds now work. I removed U6 and tested in my tester, and it tested good. I will replace it with a new one but wondering if a 74LS107 will work or if it needs to be a 74107. I don't have either in my parts bin.

Thanks again for all the help on this. It was nice to hear all the sounds being played and not every other one.

#28 46 days ago

It might be hard finding a 74107 so you might not have a choice but to use a 74LS107. Probably should be ok.
Note, U6 is also used for the Add Bonus sound effect.

BTW, are you now getting any abnormal sound/noise the moment you power up (with U6 installed but R68 disconnected)?
If not you can probably just leave it as is.

Alternatively you can probably bypass the U6 chip for the mute circuit by using a capacitor to hold the mute momentarily on power-up.
i.e. a 10uF capacitor connected on the back of the board to:
Remove the R68 leg that's opposite the U6 chip. Solder a leg of the capacitor to that point, and the other end of the capacitor connect it to pin 1 or pin 4 (which both are 5 volts) of U6. If you're using an electrolytic capacitor, the positive leg goes to the 5V connection.

#29 45 days ago

There is a screeching noise at startup and will play it for now. It’s not to bad.

Ed at GPE has some 74107 and will place an order for one. I’ll update when it comes in but would imagine this will fix it.

Thanks for all the help with this board!!

#30 39 days ago

I replaced the 74107 and re-soldered R68 and sound is now working 100% Thank you so much quench! It's nice to finally hear all of the sounds play correctly.
It's a great feeling being able to hit the "resolve" button at the top of the thread.

#31 39 days ago
Quoted from troxel:

I replaced the 74107 and re-soldered R68 and sound is now working 100%

Great!
The next thing is that it's common for previous owners to fiddle with the pots on the sound board and put it out of tune.

Below was the old way I told people to tune their SB-100 sound boards but the linked online piano player changed interface so doesn't quite match the instruction - if you're musically minded you'll work it out.

Note this if for later lower pitched SB-100 boards:
https://pinside.com/pinball/forum/topic/sb-100-no-sound#post-3966433

This if for your early SB-100 sound board that's higher pitched which most people hate - you might want to scale the pitch lower to your preference:
https://pinside.com/pinball/forum/topic/tech-hot-hand-sb-100-no-sound/page/2#post-3930780

#32 39 days ago

I asked about how to tune one of these back in 2008 on RGP when I rebuilt mine. It fell on crickets.
Good information!

#33 39 days ago

It's amazing how difficult it is to find a properly tuned classic Stern SB-100 game on youtube.

This sounds right for Lectronamo (SB-100 rev A), but some hate the high pitch. Scale it down to your liking. Note how the tones sound musically when coins are inserted and when the game starts. Note2: the Add Bonus sound effect isn't working properly on this particular game.

The only decent example of Hot Hand (SB-100 rev C1) I could find was a VitrualPin video - this is how my Hot Hand sounded when I got it.

Try this online piano:
https://www.onlinepianist.com/virtual-piano

Disable the "Sustain", and enable the "Letter Notes" and "Keyboard Marks" features.

The following piano keys closely match the tones that the SB100 Rev C-1 board was tuned to which are the notes for a C# Major chord.

Keep hitting a 10 point score and adjust the R2 pot on the sound board until the frequency matches the Black piano key 6 (note G#3) [208Hz]

Keep hitting a 100 point score and adjust the R13 pot on the sound board until the frequency matches the White piano key R (note F3) [175Hz]

Keep hitting a 1000 point score and adjust the R6 pot on the sound board until the frequency matches the Black piano key 2 (note C#3) [139Hz]

#34 36 days ago

I acquired a second Lectronamo unit that sounds factory. i will have to boot it up and get some proper video of it.

#35 36 days ago

That that's my restored Lectronamo in the top video you posted. I had to replace all the pots on the sound board so it messed up all the factory set sounds. I just had to take a stab at it to get it going.

#36 35 days ago
Quoted from wolffcub:

I acquired a second Lectronamo unit that sounds factory. i will have to boot it up and get some proper video of it.

I am curious to hear this and see how far off my sounds are.

#37 35 days ago
Quoted from wolffcub:

I acquired a second Lectronamo unit that sounds factory. i will have to boot it up and get some proper video of it.

You mean a second Lectronamo SB-100 sound board or complete Lectronamo game? We look forward to hearing it.

Quoted from wolffcub:

That that's my restored Lectronamo in the top video you posted. I had to replace all the pots on the sound board so it messed up all the factory set sounds. I just had to take a stab at it to get it going.

You got the tones tuned properly with respect to each other. If you switch the game to simulated chimes (set dip switch 23 to off on the MPU board), do the frequencies sound like mechanical chimes? A video would be great if you could
Your Add Bonus sound effect isn't working properly in that video above - it's just producing a high pitch tone and this effect isn't controlled by the pots , i.e. the board has some other issue.

Listen to the Add Bonus sound effect when the ball goes over the red rollover buttons in this video:

#38 35 days ago
Quoted from Quench:

You mean a second Lectronamo SB-100 sound board or complete Lectronamo game? We look forward to hearing it.

You got the tones tuned properly with respect to each other. If you switch the game to simulated chimes (set dip switch 23 to off on the MPU board), do the frequencies sound like mechanical chimes? A video would be great if you could
Your Add Bonus sound effect isn't working properly in that video above - it's just producing a high pitch tone and this effect isn't controlled by the pots , i.e. the board has some other issue.
Listen to the Add Bonus sound effect when the ball goes over the red rollover buttons in this video:

I have a full second machine and and another spare playfield for it.

I know my sounds are off but is it just me or are the factory sounds more screechy? Mine feel more warm i think.

#39 35 days ago
Quoted from wolffcub:

I know my sounds are off but is it just me or are the factory sounds more screechy? Mine feel more warm i think.

Can only comment once we can hear your factory sounding board.

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