1980 Atari Missile Command Arcade Circuit Board Repair - 11-3-2024

[@youvsyou945]

Fun one, thanks Sean....great job!

[@daboneyard]

fantastic videos. great insights from your troubleshooting process. I don't own or repair arcade machines, but the principles apply to the computers I tinker with. and that fluke is so cool.

[@rhett2712]

Another great repair Sean!

[@taltechchip5827]

I enjoyed your troubleshooting. Nice fix

[@darylhudson777]

And I'm a teenager again... played that game a lot...👍

[@brucetungsten5714]

Awesome video!

[@classicarcaderepairs4818]

Thanks!

[@piratestation69]

Do you have any experience with bootleg gyruss boards?

[@classicarcaderepairs4818]

yes I do

[@piratestation69]

@classicarcaderepairs4818 board boots no real graphical issues but half the sounds do not work. The board originally had no sound due to bad amps. Replaced both amps. Most of the gun fire effects do not work or sound like constant tones. Music is a bit off as well. The board is defaulted to mono. 2 vol pots only one works. Roms seem to be good. There is one 2716 i can not test. The rest are 2764s. Replaced all sound chips no change... any ideas?

[@senilyDeluxe]

@@piratestation69 Not the sound chips, not the ROMs? That only leaves the addressing glue logic to the sound chips. Should be simple 74xx logic. You might also wanna check out the RAM. I've had 2114s fail with just a few single bit errors (like maybe 3 out of 4096 bits bad). Might of course also be a bad trace to one or more of the sound chips (check if all 8 data bits and all used addressing bits make it to all of the sound chips). I've had a Bomb Jack (3 sound chips) with half the sounds missing or weak. Turned out most of the audio coupling caps were bad or completely open. There's also the remote possibility of the sound commands getting garbled (like missing a bit), so it plays the wrong sound effects. You should modify your cabinet to stereo (or just hook up a second speaker). On Gyruss it absolutely pays, it has absolutely epic stereo sound if it works.

[@piratestation69]

@@senilyDeluxe one thing about boots the solder joints are horrible. My boards are run though a supergun. I have replaced some of the caps. Dont have a scope. There homebrew diag rom that tests everything. No ram errors. Looked around for hot chips nada. Im very limited on what i can do but ill look into what you said.

[@senilyDeluxe]

@@piratestation69 A logic probe will do in a pinch on simple 74xx logic. If you don't have one, you could make a video probe (disconnect one of the color outputs to the monitor and use it to probe the IC pins). You should see your color go to digital static if there's a signal, so you can check for example if you have a simple logic gate, both inputs have a signal and the output doesn't, then that's likely your fault. An even more rudimentary method would be using headphones. Connect the outer ring to ground and the tip to a capacitor and maybe a resistor and probe away. A single click means no signal. Buzzing means signal. Disadvantage is you're loading the signal down so the CPU might crash depending on where you probe. Go dumpster diving. I've pulled out three scopes so far that all just needed minimal servicing to get going. Also, 70s/80s CRT scopes can be had on fleabay for very little money. For fixing game boards up until the 90s, 10MHz bandwidth is all you need. A late 60s scope beats a late 90s/early 2000s digital scope when it comes to video circuitry. (although you'll run into age-related unreliability issues on scopes that old. Heck I'm from the 80s and I'm experiencing unreliability issues already.)

[@2011MoJo]

First!