Missile Command switching power supply.

tbbk

Well-known member
Joined
Oct 30, 2001
Messages
15,402
Reaction score
109
Location
Missouri
Can anyone point me to a basic walkthrough to eliminating the AR II on a Missile Command and installing a switcher and a separate audio amp?

Just picked up a dead one with a disintegrated power switch. After I bypassed that I found it had .46 volts. I was about 2 components in to the AR II repair kit when I remembered that "Gee, you have multiple working AR II boards here already".

So, I tossed in a working one, powered it up, got a red light on the main PCB and the AR II immediately started trying to burn up a resistor. So I shut it down before it could finish that job and started thinking about switching power supplies, because I am sick and tired of dealing with AR IIs.
 
What does the fingerboard on the PCB look like? I am betting that is the root of your problem. A problem that would have to be corrected even if you went to a switcher.
 
Went ahead and replaced the big transistor on the AR II and did the sense mod.

Got 4.4ish volts and the game gave me beeps and tones when plugged in.

Ran additional +5 and ground wires between the AR II and the PCB test points (pole position style) and I was able to get +5.0 at the PCB (after tuning that little knob on the AR II that is normally glued down).

With +5.0 on the PCB both start buttons light up solid, but I get no video or audio out of the board.
 
Went ahead and replaced the big transistor on the AR II and did the sense mod.

Got 4.4ish volts and the game gave me beeps and tones when plugged in.

Ran additional +5 and ground wires between the AR II and the PCB test points (pole position style) and I was able to get +5.0 at the PCB (after tuning that little knob on the AR II that is normally glued down).

All of that screams burned up fingers and pins on the board and in the harness. Some call the sense thing a "mod", some refer to it as a "hack" because your hacking around it to cure the symptom of a larger issue.

With +5.0 on the PCB both start buttons light up solid, but I get no video or audio out of the board

The pin out on Mike's Arcade shows MC using +12 and -5. Not sure where they go or what they are used for (not had to work on a MC) but I am sure they are there for a reason. Did you look at those?
Overall, it its been run long and hard enough to cause the problems you have on the +5v side I would go on and shotgun the AR, and address the fingerboard and harness so that you know what you have before you try and troubleshoot board issues.
 
I didn't specifically do anything about +12 or -5 because from what I understood the +5 connections are the major problems in AR II equipped games.

For now I shoved the thing into my shed. This is going to the back of the repair line since it is also missing both the glass and the tinted plexi, and it will need trackball rebuilds.
 
It's the fingers on the pcb, or it's the connector it's self.. Once an AR is rebuilt, 99% of the time it's trouble free. I've rebuilt and sold over a hundred ARs in the last few years.. Never have I sense modded them, and I've not yet had a return or complaint.. The few that have burned resistors were because of the harness or poor connection to the harness. Replacing the big blue won't fix your problem.. Cleaning and installing a new connector will fix your issuE.

Without your ARII, you won't have sound by the way.
 
I understand it is the power connection degradation keeping me from getting normal power. I did the sense mod hack and edge connector bypass to see if the board even worked once it had 5 volts, and it didn't. Missile Command isn't a cheap board and this cocktail is missing the glass too, so it goes to the back of the repair line.
 
Back
Top Bottom