VR201 cable replacement

VR201 displays can be quite difficult to find, and when they are found they often suffer from severe cataracting. If you do not have a VR201 or have not had the time to fix yours, the following will allow for the use of a standard VGA monitor in its place. This could probably be adapted quite easily to support a VR241 as well but my system is mono only so I have not tried.

References:

• NetBSD: LK201 Interface
• DEC Rainbow VR201 DB15 Connector Pinout

• DB15-F and RJ11 terminal blocks, or the tools to make something more permanent. The pinouts that follow worked for me with these Amazon products but you will want to verify correct pinning yourself.
• A standard VGA cable and some spare shielded wires
• A wire stripper
• The picture you get may be quite fuzzy or hard to read, or your monitor just may not display anything at all- in this case you will need some kind of upscaler and scan converter. I have used an OSSC in the past, but after a report from CCMP user vtgearhead that the Extron RGB-HDMI 300A works perfectly I am now using one of those and my OSSC is once again with my retro consoles.

Cut one end off the VGA cable and strip the plastic to expose the wiring. You will only need three: VGA green (should be green), its ground (copper wire typically wrapped around it), and the VGA ground wire (should be black). Verify this yourself using a multimeter to ensure you have the right wires.

Next, strip both ends off your spare shielded wires, we will need four for the RJ11 portion. The RJ11 pinout assumes you have the connector oriented as in the NetBSD document linked above, included here just in case:

    |----- data -< -------------------------------------------|
    |    |-------- >- Power -----------------------------|    |
    |    |    |------------- GND -------------------|    |    |
    |    |    |    |------------- <- data -----|    |    |    |
   -------------------                        -------------------
  | "    "    "    "  |                      | "    "    "    "  |
  | L    V    G    D  |                      | D    G    V    L  |
  | K    +    N    E  |                      | E    N    +    K  |
  | ->        D    C  |                      | C    D         -> |
  | D             ->  |                      | ->             D  |
  | E              L  |                      | L              E  |
  | C              K  |                      | K              C  |
   --               --                        --               --
     |             |                            |             |
      --         --                              --         --
        |       |                                  |       |
         -------                                    -------

     Looking into the                       Looking into the DECstation
     LK201 Connector                                 Connector
   (Socket on keyboard)                        (Socket on DECstation)

Wire everything up to the DB15-F block using the following pinout:

VGA green -> DB15 pin 12 (mono out)
VGA green gnd -> DB15 pin 4 (mono gnd)
VGA gnd -> DB15 pin 5 (gnd)
RJ11 pin 1 -> DB15 pin 15 (kbd rx)
RJ11 pin 2 -> DB15 pin 6 (gnd)
RJ11 pin 3 -> DB15 pin 7 (+12v)
RJ11 pin 4 -> DB15 pin 14 (kbd tx)

Take care not to swap pins 2 and 3 on the RJ11, or your LK201 will eat +12v over ground and fall over dead. Verify your pinout with a multimeter before plugging the cable into your LK201. VGA goes wherever. No more cataracting!