I'm in a trouble. Can someone help me?

I have a very big machine where I had mounted an IBM 5151 monitor by VGA. The VGA cable was connected to the card below (see attachment), by 4 wires.

Now the monitor is broken and I'm in trouble. Can anyone help me?

I want to connect a single RCA wire (the yellow) directly in the card in place of the 4 wires of the VGA (wires grey, green, pink, white, to be clear.) The RCA cable has 2 wires, one yellow and one black.

What can I do?

Please it's really important.

enter image description here

  • 2
    \$\begingroup\$ No the output is not VGA. It is MDA. It is not compatible with VGA in any way. I am having trouble deciding if this is a repair question without understanding the device being repaired, what to buy question, or how to use devices question. \$\endgroup\$
    – Justme
    Nov 12, 2020 at 11:07
  • 1
    \$\begingroup\$ the circuit looks suspiciously like an MDA to compositie converter. find someone who knows the device they will tell you which pin has compositie video on it. \$\endgroup\$
    – Jasen
    Nov 12, 2020 at 11:09
  • 1
    \$\begingroup\$ @Jasen MDA being 18.4kHz 50Hz would not be compatible with composite 15.6kHz 50Hz. \$\endgroup\$
    – Justme
    Nov 12, 2020 at 11:15
  • 1
    \$\begingroup\$ Here's the Original Monochrome Display and Parallel Printer Adapter found on the IBM PC (IBM 5150). In the top-right corner you can see the 9-pin MDA output. It's not a 15-pin VGA output. \$\endgroup\$
    – tim
    Nov 12, 2020 at 11:47
  • 1
    \$\begingroup\$ That's the MDA connector and here are the MDA pin-outs. \$\endgroup\$
    – tim
    Nov 12, 2020 at 12:02

1 Answer 1


There are a number of problems you have here:

  • VGA is 15 pins, not 9

  • RCA is composite video, not VGA

  • IBM 5151 is neither of those, it's an old standard "MDA" (monochrome display adapter).

It appears from the internet that MDA isn't a subset of VGA - you can't convert from one to the other by simple wiring.

Your options are:

  • find an old IBM 5151 that is still working, or repair the broken one

  • buy an MDA to VGA converter and wire it appropriately. "Industrial" versions of these can be found on Aliexpress and other vendors; it seems that this is a common problem of industrial equipment with obsolete monitors.

  • trace the video signals further back from that board and find a more useful one (unlikely, since this looks very old .. how old is it? 80s?)

  • \$\begingroup\$ I want to remove the VGA and put into the 1,3,4,6 slots (see the image) only 2 cables (the cables from the rca yellow). I had tried it and for seconds it works, but after removed it the connection was losted... So i don't know where put the positive and the negative of rca (what slots from 1,3,4 or 6)... \$\endgroup\$
    – Marc Aurel
    Nov 12, 2020 at 10:52
  • 5
    \$\begingroup\$ @MarcAurel This answer clearly explains that there is no "VGA" here and that an MDA signal is not compatible with composite video, which makes your commenting pretending otherwise quite disappointing. Until you recognize the reality of the situation there's really no way anyone can help you, that said the question isn't on topic here anyway. \$\endgroup\$ Nov 12, 2020 at 16:13

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