This board replaces the original and very poor VIC-20 video output stage, improving the composite output and adding S-Video. Not only are jailbars, checkerboarding and noise significantly reduced or eliminated, edges are enhanced without unwanted ringing.

Feature summary

• Compatible with both PAL and NTSC
• Fits both the Longboard and Shortboard VIC-20 and the Vicky Twenty
• Vastly improved composite output
• Sharp S-Video output
• Adjustable luma:sync ratio (contrast fine tune)
• Does not require the VIC to be in a socket
• Fully assembled and ready to install

Install

Longboard (2 prong power jack)

Start by removing (or lifting a leg of) the following 4 components:

C18 and L2 (near the AV DIN jack), FB7 and FB16/R33 (these are the two components connected directly to pins 2 and 3 of the VIC, FB16/R33 may be a ferrite bead, resistor, or whatever else Commodore had laying around).

Place the video upgarde board on the underside of the mainboard, underneath the VIC. Make sure the <- POWER SWITCH indicator is pointing towards the power switch. Flow solder into the plated through holes, note only pins 2,3,20,21 and 40 are plated. The other holes are not plated and will not accept solder even if you try. This was done to make removal slightly easier, not that you'll ever want to after seeing the results.

For composite only: Solder one of the included wires between the C.V pad on the upgrade board to pin 4 of the AV DIN. That's it, you're done!

For composite and S-Video: Remove or lift a leg of FB17 (it may not be labelled but it will be the component to the right of capacitor E2). Cut the 5V trace going to pin 1 of the DIN and make 100% sure that trace is cut. Then using the included wires, solder CHR to DIN pin 5, C.V to DIN pin 4, and LUM to DIN pin 1.

Shortboard (DIN power jack)

Start by removing (or lifting a leg of) the following 4 components:

Q2 and R13 (mid-left of the VIC can), FB7 and FB8/R41 (these are the two components connected directly to pins 2 and 3 of the VIC, FB8/R41 may be a ferrite bead, resistor, or whatever else Commodore had laying around). On the Vicky Twenty FB8/R41 is R99.

Place the video upgarde board on the underside of the mainboard, underneath the VIC. Make sure the <- POWER SWITCH indicator is pointing towards the power switch. Flow solder into the plated through holes, note only pins 2,3,20,21 and 40 are plated. The other holes are not plated and will not accept solder even if you try. This was done to make removal slightly easier, not that you'll ever want to after seeing the results.

For composite only: Solder one of the included wires between the C.V pad on the upgrade board to pin 4 of the AV DIN. That's it, you're done!

For composite and S-Video: Cut the trace between pins 4 and 5 of the DIN on the underside of the board. Cut the thick 5V trace on the topside of the board going to pin 1 of the DIN and make 100% sure that trace is cut. Then using the included wires, solder CHR to DIN pin 5, C.V to DIN pin 4, and LUM to DIN pin 1.

Setup and usage

AV DIN pinout

If only using composite you can continue to use your current cable or adaptor.

For S-Video the pinout matches the Atari XL/XE pinout where 1= S-Video luma, 2= GND, 3= Audio, 4= Composite, 5= S-Video chroma

Keep in mind most basic VIC-20 S-Video mods remove composite entirely and use pin 4 for luma. While I much prefer using S-Video when possible, I didn't want to ditch one for the other. This does mean however you will need to find a cable like this one (note I am not affliated and cannot vouch for the quality of these), or this one (black=audio, white=luma, red=chroma, yellow=composite) which is perfect for Commodore monitor users or with a 2xRCA to S-video adaptor, or you can roll your own cable. I'm not in the cable making business sorry :-)

Contrast fine tune trimpot

To find the ideal value for your VIC and display combination, power on the VIC-20 and adjust the small potentiometer (be gentle) on the upgrade board until the white foreground becomes a very light grey. Then turn it slightly in the opposite direction stopping when the foreground is pure white.

Note this adjustment may have little to no effect depending on your display or upscaler - in which case it is recommended just to leave the trimpot at the mid position.