Missile Command Issues

daley

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Donor 2011
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So, I just did an A/R Repair kit (from Bob Roberts) and a power supply rebuild kit. Afterwords, I turned plugged the board in to the cabinet and measured the voltages. The -5 was reading -15.

In addition while reading the voltages after a short while either the J7 or J8 connectors started smoking. Hard to tell which it was as they are above and below each other.

Any ideas on what could be going on here?
 
The tab of Q9 (7905) -5v regulator should be isolated from the heatsink, did you use an insulator and a plastic screw? otherwise you'll be causing all sorts of mayhem.

Oh, and modern 7905 -5v regulators will often have a completey screwey reading when they are not under load, often showing way below -5v.

Your connectors might not be smoking, it may be R29/R30 near them if you havn't disabled the SENSE. on the underside of connector J7, solder pin 1 to 2 and pin 3 to 6. for detailed info on why, you can read this:
http://www.andysarcade.net/personal/tech/AR2sense.txt

enjoy
 
Last edited:
And don't forget to read the counterpoint arguments to the sense mod in these threads:

http://forums.arcade-museum.com/showthread.php?t=49450

http://forums.arcade-museum.com/showthread.php?t=174734

My take on it is this:
- If you are NEVER swapping boards in the cab, maybe do the sense mod
- Otherwise, do not do the mod but make sure that damn resistor is WAY off the ARII PCB. Why? Because you want that resistor to smoke/burn instead of something on your board. And if/when the resistor burns, you want it away from the PCB and other components. Replacing a resistor is cheap and easy!
 
The tab of Q9 (7905) -5v regulator should be isolated from the heatsink, did you use an insulator and a plastic screw? otherwise you'll be causing all sorts of mayhem.

Yea I have mica between it and the heatsink, and heatsink silicone on each side of the mica. Using the same plastic screw that was in there before.
 
I checked the board again before leaving for work and it was R30 that was smoking. It is obviously burnt.

Looks like i will look into the edge connector.
 
Speaker problem now

So, replaced the edge connector and no longer had the problem of burning out the resistor, but the board was apparently not working. I picked up a working board from a fellow KLOVer and hooked it up and it worked. So got the Missile Command up and running.

However, while I now have a working monitor and seemingly working board, I am having sound issues.

I can hear the sounds very faintly from the left speaker only. Messing with the volume knob makes no noticeable difference. And when I say very faintly I mean that I need to put my ear practically against the speaker grill in order to hear it. So the board is producing the sound and it is getting to the speaker, it just seems like it is not being properly amplified.

Thoughts?

Thanks!
 
Could be bad TDA2002s on the AR2. Cost you very little to replace those.

That was exactly the problem. Got two of these from Bob today and went ahead and replaced them. Sound is perfect.

Missile Command is now running beautifully, thank you everyone.

Now I just need to get off my ass and deal with all the cosmetic stuff :)
 
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