Connecting to a Composite monitor
Yes, you can connect your Bally/Astrocade to a composite monitor. Unfortunately the method described in the pages of the Arcadian (V5 #8 P129) only gives a monochrome output. Or at least that's all I got.First you will have to open your machine. Not to worry you can't void any warranties
as there isn't one anymore! 
However
I cannot take responsibility for what YOU do under the hood. A little soldering
will be required, but NOT near major parts.
Now that you have the cover off. Only the TOP please. you will notice on the left (the front of the machine Facing you) an RF box.
Lift the left edge & pull out to the left. There are now a row of 8 large square metal pins coming off the motherboard. For the sake of this job we will number them from front to back 1 to 8. solder a 300 ohm resister between pin 1 and the shield. Now get 2 single ended RCA cables. Solder their shield wires to the shielding. Solder the centre of the Video cable to pin 1. Solder the Audio cable to pin 3. Be sure to attach them close enough to the board to allow the RF box to be replaced.
Replace the RF box & close up your machine. You're ready to go!
OPTIONAL:
If you don't really want new cables coming out of strange places in your machine You might try what I did. I mounted a 5 pin din connector to the back left corner of the case bottom. Fit's nicely if installed with the mounting holes 45 from horizontal. Wire to this and use a Commodore 64 monitor cable to connect.This allows you to remove the cable for storage, & is virtually invisible when not in use.
Din Pinout: O---NC--O Video-----O O----Audio O-Ground
OPTION 2:
Thanks to the people at Active Surplus, and Brett Bilbrey I now have a complete pinout list for the RF box inside the Bally/Astrocade systems! Pins will be numbered as above.
Pin Tech Comment
---------------------------------
8 GND Ground
7 B-Y Blue-Luma
6 R-Y Red-Luma
5 Chrom Bias Chroma no sync??? Guessing.
4 Chrom 3.57Mhz Chroma with Sync?? "
3 Sound Sound
2 +12V Power for RF
1 Video Luma + snyc.
If anyone can get a full colour RGB video working please let me know.
Note from Brett: The 'video' is really just the luma ('Y') portion of the video signal, the chroma is made up of the Red minus the luma, and the Blue minus the luma. With this, you have enough information to reconstruct RGB information. The reason Y, R-Y, B-Y signals are used is they conserve bandwidth. The chroma signals can be half the bandwidth of the luma and still maintain the full signal content. High-end broadcast digital tape machines use this format and it is called 4:2:2 sampling.
Joystick Rewiring
There are 2 ways to do this. 1) remove the existing cable and use a joystick extension cable to rewire.(Ok if you don't need to use it with the Bally any more) or 2) make a translation plug or "Gender Bender" of sorts.Those wishing to keep the knob function should note that the Bally uses a different restive value for the pot than Atari/Commodore. To this end I actually removed the resistive board from the Bally pot & replaced with 1 from an Atari Paddle. (Tricky but doable)
It's also possible to wire an Atari/Commodore joystick to replace a Bally/Astrocade one. However I'm not sure how to include the Knob function. In anycase the important wiring chart is Below.
Bally/Astrocade Atari
Controller port Joystick port
1. Trigger 1. Paddle B
2. Right 2. Right
3. Left 3. Left
4. Down 4. Down
5. Not Connected 5. Up
6. 50K Pot (Knob) 6. Paddle A
7. Ground 7. Ground
8. Pot end 8. +5v (Paddle end)
9. Up 9. Fire Button
As per Bally Manual
DB9
1 2 3 4 5 (Looking at Plug end)
6 7 8 9
The numbering above is reverse to the industry standard. This has made it difficult
when working with pre-numbered DB9 ends.Below is the matching pinouts.
Bally/Astrocade Atari Standard
Controller port Controller port
1. NC (No Connection) 1. Up
2. Down 2. Down
3. Left 3. Left
4. Right 4. Right
5. Trigger 5. Paddle Potentiometer B
6. Up 6. Fire Button
7. Potentiometer end 7. +5v (Paddle end)
8. Ground 8. Ground
9. 50K Potentiometer (Knob) 9. Paddle Potentiometer A
DB9 Male Port: DB9 Female Plug:
1 2 3 4 5 5 4 3 2 1
6 7 8 9 9 8 7 6
An Atari-Bally controller converter may be constructed.
The connections are listed here:
A1-B6 A2-B2 A3-B3 A4-B4 A5-NC B1-NC A6-B5 A7-B7 A8-B8
A9-B9
.... where (A)tari (B)ally.
Thus adapters can be made to connect an Atari compatible controller to the
Bally/Astrocade or vice versa.
Please note that the Bally/ Atari/ Commodore paddles use different value
potentiometers and additional work is necessary to make one controller
work with another console. Adding A resistor in parallel will help if the
sweep (Max turn) is too long. Other?
Also note that the Bally/ Astrocade port does not provide voltage. Thus
autofire circuits will not work when plugged into the port. But the
ambitious tinkerer may build an autofire circuit tapping the light pen port.
Light Pen (Back of arcade)
1. Ground
1 3 2. LP
2 3. +5
Controller Maintenance
----------------------
Opening the controller: 4 screws hold the two black clamshells together.
Be careful not to lose the trigger parts or screws when opening.
Joystick and trigger contacts may be cleaned with a cotton swab soaked in
isopropyl alcohol. Also the potentiometer may be cleaned with two or three
drops of alcohol into the casing then twist the knob vigorously about 30
times.
A frayed / broken cable may be replaced with a Genesis or other 9 wire cable.
A broken black casing may be glued with plumbing glue.
Be careful to put the clear plastic wrapping back in place when
reassembling.
