Space Invaders Board Repair: Log and Cries for Help Along the Way

[mecha]

After getting sound hooked up I was able to test and determine that all sounds work besides "explosion". When explosion is supposed to happen all I get is a "pop" sound. Just as described in another forum post I found



This sounds exactly like my problem. So where can I buy these 4006 chips? Think I will start there and then replace the lm3900 if that doesn't work.

I would encourage looking all the green caps over on the game board (sound board) because they're prone to getting broken off. I had to do an order a few months ago to fix my Space Invaders boards, I want to say I bought them from Jameco. Explosion I'm assuming is the UFO crash sound, that does come off the noise generator and I want to say they're near unobtanium or cost a lot now if you do find any. if any of your other boards are missing the other sounds though they each have an LM3900 and those go bad a lot. the Space Invaders Trimline at work I think I had to replace all of them, the UFO crash is the only one missing and it's just going to stay that way for now lol one of my SI boards the sound was barely audible and it wound up being a bad LM3900 in like the final stage before it got to the amplifier.

I only have one other bad game board that's obnoxiously loud. I'm not sure if that same final LM3900 can go bad that way where it just goes like max volume?

 

[Officepot]

I would encourage looking all the green caps over on the game board (sound board) because they're prone to getting broken off. I had to do an order a few months ago to fix my Space Invaders boards, I want to say I bought them from Jameco. Explosion I'm assuming is the UFO crash sound, that does come off the noise generator and I want to say they're near unobtanium or cost a lot now if you do find any. if any of your other boards are missing the other sounds though they each have an LM3900 and those go bad a lot. the Space Invaders Trimline at work I think I had to replace all of them, the UFO crash is the only one missing and it's just going to stay that way for now lol one of my SI boards the sound was barely audible and it wound up being a bad LM3900 in like the final stage before it got to the amplifier.

I only have one other bad game board that's obnoxiously loud. I'm not sure if that same final LM3900 can go bad that way where it just goes like max volume?

I thought "Explosion" was strictly the player dying/getting hit. The UFO noise and hit sounds good in the schematic I figured that was "Saucer Hit". It is when the player or base dies/explodes I get no audio, just a pop noise. I did get one of the Cocktail Audio boards hooked up and it works great. All sounds working on that one. The other Cocktail audio when hooked up just displays the screen I would expect when no "RESET" is triggered and just hangs there. What can I check on the sound board to trigger the RESET? Thanks also for the advice, I will check the caps on the one without explosion and report back.

 

[mecha]

I thought "Explosion" was strictly the player dying/getting hit. The UFO noise and hit sounds good in the schematic I figured that was "Saucer Hit". It is when the player or base dies/explodes I get no audio, just a pop noise. I did get one of the Cocktail Audio boards hooked up and it works great. All sounds working on that one. The other Cocktail audio when hooked up just displays the screen I would expect when no "RESET" is triggered and just hangs there. What can I check on the sound board to trigger the RESET? Thanks also for the advice, I will check the caps on the one without explosion and report back.
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oh, yeah I'm not in Space Invaders mode right now. depending if it's Midway or Taito based on the schematics I've seen they have different terminology for what the sounds are. in fact I'm just enjoying not working again for a change.

so then you don't need a 4006, which is good news, so look over all the caps and LM3900 for Explosion.

 

[Officepot]

@mecha

Will do and report back. Thanks again! If you have any insight on this let me know:

The other Cocktail audio when hooked up just displays the screen I would expect when no "RESET" is triggered and just hangs there. What can I check on the sound board to trigger the RESET?

 

[mecha]

@mecha

Will do and report back. Thanks again! If you have any insight on this let me know:

The other Cocktail audio when hooked up just displays the screen I would expect when no "RESET" is triggered and just hangs there. What can I check on the sound board to trigger the RESET?

I don't know that deeply about SI. I seriously just popped for the expensive JAMMA adapter from Canada lol are you fixing these to run in a cocktail game?

there's a pin that's supposed to be grounded, the reset circuitry if I recall is inverted (passes through 74LS04) and you can read up more on it here since the old site is gone: https://www.arcaderepair.net/2024/01/27/building-a-midway-space-invaders-deluxe-test-harness/

 

[Officepot]

@mecha I bought 3 SI machines with many various boards. 2 SI deluxe, one red one blue. And a regular SI that is very rough shape. They came with the cocktail sound boards for some reason. I am using them in regular standup machines just because that's what I have. I will check 74LS04 and see if I can see the reset pulse. Hey! I used your test harness guide when I made mine! Thanks so much for the great detailed explanation on your site! It helps so much in testing all of these boards I was able to buy... The CRT boards is what is really daunting to me to repair. The high voltage is also a concern to me. Do you recommend any good guides? I hooked one up yesterday and a large resistor on one side of the CRT board glowed white hot almost instantly so safe to say I will not be attempting to turn those on anytime soon till I get them worked out.

 

[mecha]

@mecha I bought 3 SI machines with many various boards. 2 SI deluxe, one red one blue. And a regular SI that is very rough shape. They came with the cocktail sound boards for some reason. I am using them in regular standup machines just because that's what I have. I will check 74LS04 and see if I can see the reset pulse. Hey! I used your test harness guide when I made mine! Thanks so much for the great detailed explanation on your site! It helps so much in testing all of these boards I was able to buy... The CRT boards is what is really daunting to me to repair. The high voltage is also a concern to me. Do you recommend any good guides? I hooked one up yesterday and a large resistor on one side of the CRT board glowed white hot almost instantly so safe to say I will not be attempting to turn those on anytime soon till I get them worked out.

I don't recall ever getting a pop trying to discharge M5000/7000 KV700A or V1001 monitors, so I think they self discharge. of all the monitors I've worked on B&W raster is one art I never really cared to master. out of 1000 things, I can do 997 of them just fine. someone else can handle the other 3. lol

 

[Officepot]

@mecha I replaced the 2 LM3900s today and got my explosion sound back! That is 2/3 Space Invaders cabs brought back to life! The last one is by far the roughest... will see if I can get that one working too. First I have to get the monitor chassis working.

 

[HudsonArcade]

I replaced the 2 LM3900s today and got my explosion sound back!

Hint:
It's far more useful to verify which of the 8 LM3900s you replaced.

 

[Officepot]

Hint:
It's far more useful to verify which of the 8 LM3900s you replaced.

Yes it would be, my bad. I replaced K3 and K4. They are both listed on the schematic as "K3-4" The schematic shows them both responsible for the "explosion" sound, so I did them both. I also recommend you install sockets when replacing them so its easier to swap them out in the future. I hope this helps people with a similar problem.

 

[Officepot]

Had the machine workings great for the last few weeks. I left it on for an hour or so today and suddenly this happened... it will not come out of it. I have tried power cycling and reseating connectors. Lines with beeping noise and resetting in 10 second intervals. Where to start would be great. Thanks all!

 

[Officepot]

Done some more troubleshooting but the issue persists… thinking something on the sound board has failed

 

[wugly]

start looking for dead data lines moving between boards. Of course you have proven all 3 voltages on the board

 

[Officepot]

I have went through and read the documentation on my braze kit. The 8 beeps should mean that RAM G 15 is faulty... but of course can also mean something else. I have replaced RAM 8, I now get the same scrolling screen with a watchdog reset on occasion, but now, with no beeping at all! Sometimes when i plug the board in I get every single space invaders noise at the same time... this will continue until I remove power from the game. This happens while the game is still showing the random stuff on the screen, and resetting on occasion.