Audio/Regulator II (AR2)
last updated March 6, 2011
The AR2 is quite a nifty bit of
kit, and Atari even engineered it for future expansion.
To my knowledge hower, they never actually built any of them with the fully loaded +/- 15v regulator section.
On the schematics for Centipede
it shows a dashed box around the optional components in the AR2 schematic.
They obviosuly intended to add a +/- 15v section, as this is the voltages used by the AVG section of most vector games
but they decided not to, and all vector games have this regulator section on the game pcb itself.
Now, the screening on an A035435-02
AR2 that I used doesn't specifically say +/- 15v, it just shows +VE and -VE
indicating that any regular 78xx and 79xx 1A regulators could be used for whatever volts you wanted.
Of course, the input supply was not fixed either. In the example below i will show how to put in a -12v regulator (7912)
this regulator uses the -22vDC on the AR2 as its input, but you could in theory use the raw 36v AC if you wanted to use a
7924 (-24v) regulator, which the -22vDC supply is too low to supply. This requires more mods not covered here yet.
so take a look on the right hand
side of the black heatsink,
you'll see a bare section of silver bits but no components loaded like this:
for this page, we are dealing with
adding a negative fixed voltage regulator, so clear the holes as shown below:
(clearing the test point holes is optional, i did it afterwards)
it should be fairly obvious, but
you can see the tracks on the underside of the pcb
quite clearly through this pcb which is handy for our purposes :)
Then all you have to do is fill the space with the compoennts as per the schematic:
C30 is the leftmost cap, a 2.2uf
50v, C36 is the rightmost cap, a 1uf 63v.
The TO220 regulator is a 7912, and i used bell wire for the test point and the link,
to the left of the regulator that brings the -22vDC forward for the regulator to use.
thats about all there is to it
really, fairly simple really..
Just remember that pin 10 of connector J10 now carries -12v
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