Hi! I recently got my first pinball machine, a Stellar Wars with a System6 CPU and Type1v2 sound card. It's in ok shape but needs some deep cleaning and a little work.

The game plays well and the family loves it, but it has a sound problem. Sometimes the sound works perfect, most times not. It can miss sounds (triggered/sweeping/counting points after lost ball), double play sounds (triggered), distort sounds (all), and sometimes even start playing a continuous distorted hum sound.

After studying the schematics and reading repair guides online, I've gone as far as I can with the tools and experience I have and could use some guidance.

Here is what I have been able to test and what the results are:

1. Sound card test button: Single repeating sound, no distortion, as expected for this card and sound rom 1.
2. Solenoid test: Single sound for each sound solenoid fired.
3. Short each of the 5 sound card 10J3 pins to ground: Single sounds as expected.
4. Short each of the 5 sound connector wires in 2J9 connector to ground: Single sounds as expected.
5. Short Solenoid transistors 9,10,11,12,13 metal tabs to ground: Single sounds as expected.
6. +/-12VAC input voltages were good, -12VDC good at C30, +12VDC good at C29, +5VDC good at C27.
7. Measure voltage at 10J3 pins with wires disconnected: 1(Key), 2(5.1V), 3(3.2V), 4(5.1V), 5(5.1V), 6(NC), 7(3.1V), 8(NC), 9(NC)

The voltages for pins 3&7 seem low. I followed 10J3 Pin3 on the sound card through J9/R29/R37/C16 to buffer IC8 pin9 and the voltage is still low, related IC8 pin10 is 5.1V. Same results for tracing 10J3 Pin7 back to buffer IC9 pin9 and 10.

Where do I go from here? Is ~3V ok and I'm going the wrong way? Do I need to replace IC8 and IC9? Or are the low voltages completely unrelated to my sound problems during play?

Thank you!

(Wow, that was a wall of text for a first post!)

It looks like only the 12000mfd cap has been replaced, I'll order that kit when great plains store is back open for good measure. It's a good idea even if it does not fix my problem. Thanks for pointing it out.

I'll also order replacement buffers and sockets to see where that gets me.

Too bad I can't convince my wife I need a 2nd pin for "testing purposes". Lol. Any chance someone around Indianapolis could test my board in their machine before I start replacing parts?

Haven't worked on the board yet. Debating on sending it to johnwartjr with the cpu and driver boards or ordering parts when great plains electronics reopens tomorrow.

I saw somewhere you could modify a newer square version to work, but I wish someone made a replacement. I can buy new versions of the 3 other boards in the pin.

Would be even neater if you could have a new one with an SD card and new sounds. Something like this: https://pinside.com/pinball/forum/topic/custom-sounds
but supporting trigger combos so I could get the sweep sound and the points tally sounds, not just the 5 individual triggers.

Update and repair:

I did some testing with LEDs to see which solenoids were firing when using some LEDs and +5v connected to the jumpers by the 10J3 connector. The LEDs would only light up when a sound was triggered. Oddly enough this also fixed the problem, but only as long as the LEDs were connected. This made me think that at the very least one or both of the buffers went bad.

I left the LEDs connected through some family events so the machine could be played and then shipped all the boards to johnwartjr for service. I went with him because he was not far from me and has a good reputation on pinside. He found that the main sound problem was that the 4050 buffer at IC9 was bad. It was replaced, sockets were upgraded, board re-pinned, and caps replaced. He did a great job on all 4 of the boards and my Stellar Wars is now running and sounding great.