So, I have a Missile command that was completely dead when I inherited it -- dead monitor, no signs of life from the game boards. The internal wiring of this cab is a bit confusing. There's 2 ISO transformers, one standalone, and one part of the power brick on the bottom of the cab (next to the big blue cap). There's a place where the white/black AC wires are cut and held together with quick disconnects for no apparent reason. Not sure why this has been done.
Here's a list of progress I've made so far:
GO7 was completely dead. Rebuild kit from Bob Roberts brought it back to life. Can't get the picture to quite snap into sync, slow roll horizontally no matter what I do. That's for a different thread though, and I haven't checked Fromm's flowchart yet so that might tell me what to do anyway. Monitor has nice sharp bright color, though, which is a great start.
AR/II had a blown R29 and R30. I replaced them and performed the sense mod so I could do some further testing without damaging anything (in theory). Here's the test values I got: (test point value : actual reading)
36VAC: 13.6
-22VDC: -18
22VDC: 17.3
12VDC: 11.9
-5VDC: -12.7
10.3VDC: 10.3
I took out the main PCB and gave it a visual inspection. There's minor burning on the fingerboard so I know I'll need to replace the edge connector at some point. I tested all the roms and one of them was bad, so I burned a new one and replaced it. Reseated the processor just for fun. I took the board back to the cabinet and hooked it all up, powered it on. Tested at the 5vdc test point.
5VDC: 5
The light on the PCB lit up, one of the coin counters starts clicking like crazy. I hear some explosion sounds through the speaker and other random game sounds but it doesn't sound like it's working properly, no big shock given the voltages from the AR/II. Putting it in test mode doesn't seem to make any difference. I can't tell if anything was on screen because the monitor's still on the test bench due to the sync issue.
Where do I start from here? I'm assuming an AR/II rebuild is the first stop, but the fact that -36VAC (which I think is the voltage coming into the board) is off by so much makes me think that something might be wrong with the power in the cab even before it reaches the AR/II.
Anyone got any guidance?
Here's a list of progress I've made so far:
GO7 was completely dead. Rebuild kit from Bob Roberts brought it back to life. Can't get the picture to quite snap into sync, slow roll horizontally no matter what I do. That's for a different thread though, and I haven't checked Fromm's flowchart yet so that might tell me what to do anyway. Monitor has nice sharp bright color, though, which is a great start.
AR/II had a blown R29 and R30. I replaced them and performed the sense mod so I could do some further testing without damaging anything (in theory). Here's the test values I got: (test point value : actual reading)
36VAC: 13.6
-22VDC: -18
22VDC: 17.3
12VDC: 11.9
-5VDC: -12.7
10.3VDC: 10.3
I took out the main PCB and gave it a visual inspection. There's minor burning on the fingerboard so I know I'll need to replace the edge connector at some point. I tested all the roms and one of them was bad, so I burned a new one and replaced it. Reseated the processor just for fun. I took the board back to the cabinet and hooked it all up, powered it on. Tested at the 5vdc test point.
5VDC: 5
The light on the PCB lit up, one of the coin counters starts clicking like crazy. I hear some explosion sounds through the speaker and other random game sounds but it doesn't sound like it's working properly, no big shock given the voltages from the AR/II. Putting it in test mode doesn't seem to make any difference. I can't tell if anything was on screen because the monitor's still on the test bench due to the sync issue.
Where do I start from here? I'm assuming an AR/II rebuild is the first stop, but the fact that -36VAC (which I think is the voltage coming into the board) is off by so much makes me think that something might be wrong with the power in the cab even before it reaches the AR/II.
Anyone got any guidance?
