Modifying an audio reg II-02 to audio reg II-03

mrbill2084

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Has anyone converted and ARII-02 to ARII-03? I need a ARII-03 for Missile command and I have a pile of ARII-02's.

Speaking of ARII, why do a few have 4700u 35v in c9, c10, c18, c19 while most have 3300U 35v.. Did atari just use what they had available? I have an-02 and an-03 with 4700's in it..
 
Some ARIIs have been rebuilt with Bob Robert's kits and he only supplies one value of CAP. I believe that the different cap values in the ARI boards (Ast and Ast Dlx) were for sound issues. I think I read this somewhere. Might have been Spaeth commenting on it. Why not just purchase a -03 ARII board? I honestly don't recall the difference but you can go to Electronforge and see the differences in the boards voltages. I just recently had a brain fart when I tried to put a -04 in a Missile Command and couldn't get -5 volts. It wasn't until I dug out the manual and saw that it took a -03 that I slapped my forehead. Rookie mistake. Guess lack of sleep will do that. I have some -03 ARII boards if you want to get one. I don't know if you can use a -02 it its place. I would have to wait till I got home and check my notes.
 
electron forge says:
The -03 is almost identical to the -02. Since Missile Command (and apparently Monte Carlo also) needs more current on the +12V and -5V line, it uses different current limiting resistors. Therefore, a Missile Command with a -02 installed may not operate properly.

I have about a dozen -02, so if it they are that close, it would seem easier to convert one than find someone selling an -03..
 
A -02 will (almost) always work in a Missile Command. Very early Missile Command PCB's shipped with 2708 EPROMs. These EPROMs are tri-voltage....they need 12V, 5V, & -5V....thus the need for more current from the A/R II. The vast majority of Missile Command PCBs were stuffed with single voltage 2716 EPROMs, thus no need for the extra current. Long story short.....

If your motherboard is stuffed with 2708 memories, you need a -03
.
If your motherboard is stuffed with TMS2716's (these are a tri-voltage 2716....I've never seen Atari use, but I'm covering all bases, just in case), you need a -03.

If your motherboard is stuffed with (non TMS) 2716s or 2516s, you can use a -02 or a -03.

Edward
 
Also, looking at the schematics......the only difference I can see betwen the two is R31.

-02....R31 = 22 ohm
-03....R31 = 15 ohm


Edward
 
Drop an ARII-Rev2 in there and be done with it! I've sold a few dozen rebuilt ones to MC owners and not one complaint.. Rev-3s are tough to find and not needed.
 
Yep, what Pete said;)....a -02 will be fine.
With the Braze kit installed, you can remove all the ROMs (which, I think is a good idea)....that makes for (even) less of a current draw....plus less heat (if you remove all the ROMs).

Edward
 
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