Bypassing RF modulator on Vic-20

[jseabolt]

My first VIC-20 (bought in Oct '83) must have had a built in RF modulator. If I remember it had a black cable sort of like an old stereo speaker cable that plugged into the back of the computer and the other end plugged into one of those selector boxes (Antenna/computer).

A few years ago I aquired another VIC-20 off Ebay and yet another Vic-20 a few months ago at a flea market ($1). Both require an external RF modulator. Which I have but the picture quality is not all that great. I'd like to be able to bypass the external RF modulator and use RCA cables instead.

Both the VIC-20 and Commodore 64 have an 8 pin (or something) connector on the back. On my Commodore 64, I can plug a connector into the back which turns into two RCA cables which I can feed into a monitor.

If I plug this same connector into my VIC-20 it doesn't work. So perhaps the wires are different or it's something else.

Can someone tell me what I need to do to bypass the external RF modulator?

[Gambit]

I have two commodore 64s, each with a different monitor plug. The cable that came with my 1702 monitor only works with one.

I guess thats similar to the problem you are having. I have no idea why they made different ones. Maybe different countries?

[jseabolt]

I have two commodore 64s, each with a different monitor plug. The cable that came with my 1702 monitor only works with one.

I guess thats similar to the problem you are having. I have no idea why they made different ones. Maybe different countries?

That was my guess. I'm thinking the external RF modulators for the VIC are either NTSC or PAL as well as the power supply. So to streamline production they made one computer. Or maybe by the time late 1983 rolled around someone made the RF modulator small enough to fit inside the computer.

I got my original C64 in 1984. For Christmas I got this orange monochrome monitor made by Phillips but had another name on it.

I think this monitor was made specifically for a Commodore computer because it came with a cable that had two RCA plugs on the back and one of those 8 PIN connectors. I have yet to test it to see if it works on a modern TV with RCA jacks.

One reason I'm wanting to get away from the RF modulator (other than poor picture quality and a humming noise in the background) is so whenever I want to toggle between my C64 and VIC20, all I have to do is just unplug some cables. That way I can use the same monitor, disk drive, tape drive, joysticks and power supply for both computers.

[sjgray]

I have two commodore 64s, each with a different monitor plug. The cable that came with my 1702 monitor only works with one.

I guess thats similar to the problem you are having. I have no idea why they made different ones. Maybe different countries?

That was my guess. I'm thinking the external RF modulators for the VIC are either NTSC or PAL as well as the power supply. So to streamline production they made one computer. Or maybe by the time late 1983 rolled around someone made the RF modulator small enough to fit inside the computer.

I got my original C64 in 1984. For Christmas I got this orange monochrome monitor made by Phillips but had another name on it.

I think this monitor was made specifically for a Commodore computer because it came with a cable that had two RCA plugs on the back and one of those 8 PIN connectors. I have yet to test it to see if it works on a modern TV with RCA jacks.

PAL and NTSC machines use different video chips. It's NOT int the RF modulator. There are two types of video connectors for Commodore's; 5-pin and 8-pin. There are variations in the pinouts for various machines. The 8-pin connector was used to allow separate chroma (colour) and luma (monochrome) signals to provide a better video picture (same as S-Video). The following is a summary of video connectors for the various machines:

Code: Select all

            8              7
Commodore          6           Video Connector
            3              1
 
              5         4
                   2
                                                    Plus4     C16/C128
     CBM-II      VIC20     VIC20CR    C64     Pin C64A/SX64   C64B/C/E
    --------- ------------ ------- ---------- --- ---------- ----------
(R) Luminance +5 V         +5 V    Monochrome  1  Monochrome Monochrome (Y)
    Ground    Ground       Ground  Ground      2  Ground     Ground
(B) V. Sync.  Audio        Audio   Audio       3  Audio      Audio      (W)
(W) Video     50 Ohm Video Video   Video       4  Video      Video
(Y) H. Sync.  Video        Video   Audio In    5  Audio In   Audio In
                                               6  Chroma     Chroma     (R)
                                               7
                                               8             +5 V