Help me resurrect Tempest

thrak

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I just got a few of my games out of storage. They had been stored for nearly 12 years. Tempest was in working condition when stored.

Anyway, when I power Tempest, I get no sound and no video. I do have LEDs lit on both the PCB and the monitor board. I also get the one and two player start buttons flashing, but they may be because I the game configured to free play.

I checked the fuses, and they seem fine. I could see no obvious disconnected wiring.

One odd thing is that I could not find any test mode switch inside the coin door. There is the volume pot mounted inside with what appears to be an extra button just hanging off. The extra button looks similar to the 1 or 2 player button.

Anyone know a good place to start? Any good trouble shooting manuals? Any good wiring diagrams to start checking voltages, connections, etc. I am a newbie at this, but would like the experience.
 
I would search the forum because I'm sure Tempest has been covered here numerous times. That's how I got mine working. There's so much to that game especially the monitor.
 
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First I would check the +5 on the motherboard. Does the game play blind ? Can you hear anything ? If the +5 is there and you can hear it play, you probably need a monitor rebuild. If the +5 is there and you can not hear it play, I would pull the motherboard out and reseat every socketed chip on it and try that.

edit: pretty sure there is a +5 test loop on the motherboard to check your +5
 
If the LED on the monitor board is on, that's the spot killer, which means the monitor isn't seeing the signal (and if you don't hear the game playing, the game board likely isn't running). I'd test the voltages, visually check everything, clean socketed chips and connectors, etc.

DogP
 
I finally got a chance to recheck some things last night. First thing I did was adjust the +5 on the PCB board. I used the method described here. It was reading around 4.8 so I adjusted it close to 5.1.

Next, I took out the PCB boards and visually looked it over. The interconnect cable and connectors did not give me a good feeling. It all felt fragile.

Before reseating any chips, I tried testing the +5 and GRD to each chip by using a continuity tester from the top of the pin at the chip to a test post. All of the chips tested ok except the GND on one of the ROM chips. After reseating, the chip tested fine.

I reconnected the boards and turned it on. I got a series of beeps, but still nothing on the monitor. I realized that I should take note of the beeps after I noticed a pattern of short beeps followed by a long one, but then the pattern stopped. I recycled the power, but I never got the beeps again.

Reading this troubleshooting guide it looks like it was RAM error.

Anyone know how I can get the beeps to play again?

I assume I need to start up in test mode, or hit the "reset" button, but I am not sure where these are. Like I described in my first post, I could not find the test mode switch, but there is a mysterious button hanging loose near the volume pot. I am also unsure about the reset button on the board. I saw a black/white circular thing at a location that was documented as "reset", but it didn't feel like a button. It was very rigid.

I do plan to recap the monitor and replace "big blue" and the fuse kit soon. Any suggestions or advise?
 
One other thing. I noticed when I had the boards out that the aux board had easily reachable +5 and GND posts to test voltage on it, so I did after reconnecting. I got less than 4.7 volts there when the main board was reading 5.1. Obviously something is amiss.
 
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