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A friend of mine has an electrical typewriter Triumph-Adler BSM 100 SC which is roughly from 1982 (as this site says).

The original tube monitor is faded and it's hard to read anything.

The VGA video cable coming from the monitor must be monochrome VGA. Because it's missing pins 1 and 3 but not 2. Pin 2 is used for monochrome video and this is documented only on German Wikipedia and missing on English Wikipedia. Because German Wikipedia says VGA is from 1987 I am not sure if it's VGA at all (the typewriter is from 1982). Maybe it only has the same connector.

We want to replace the monitor with a brand new flat screen.

How can this be done? I don't want a shopping recommendation. I just want to know how this can generally be done.

I searched for monochrome VGA adapters but didn't find anything. Also I don't know if modern VGA monitors support monochrome. I don't want to connect a normal VGA monitor because it could damage the typewriter and/or monitor.

VGA cable coming from the monitor

Triumph-Adler BSM 100 SC

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    That machine is clearly not from 1982 as it has a 3.5" floppy drive, which came out in 1983. Mono VGA monitors were definitely a thing as they were somewhat cheaper than colour (especially second-hand which is how I encountered them) and arguably better for wordprocessing due to the lack of a dot mask. I'd be inclined to just plug it into a modern TFT monitor which will merely complain if it's not VGA and otherwise do nothing. Don't try with an old CRT until you've confirmed the sync timings with that test.
    – pndc
    Commented Jul 1, 2023 at 15:12
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    Find someone with a scope. Record signals with the scope while connected to the old monitor, either verify it's indeed VGA (that would be surprising), or, if it's a proprietary layout, identify the signals (sync etc.). Find something that can convert an analog signal with the given parameters to modern resolutions an ordinary flat screen can understand (there are some for retro computers, they may or may not work).
    – dirkt
    Commented Jul 1, 2023 at 15:51
  • This machine was produced after the Olivetti acquisition of TA and after most of TA's original development and production sites were shut down, so should be early 90s.
    – tofro
    Commented Jul 2, 2023 at 7:19
  • For those who are interested: I connected a generic modern flat VGA screen and it worked. The picture is green but for me it's sufficient.
    – zomega
    Commented Jul 27, 2023 at 19:54

1 Answer 1

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For what it’s worth, the author of this Triumph-Adler BSM 100 SC video on YouTube calls it monochrome VGA monitor in the description.

If it indeed is one, a color VGA display with no special support for monochrome input signal would just show the picture in green color since the pin number 2 is the green channel on color VGA monitors. In order to make it neutral B&W, you would need to connect pin number 2 to pins number 1 and 3 (red and blue) as well.

You can use a multimeter to check that the signals are in the expected voltage range for VGA.

As @dirkt mentions, an oscilloscope would further let you analyze the shape of the signals and the rate of the (assumed) vertical and horizontal sync pulses, and confim that the signals are on the expected pins.

Pin number 6 is a bit curious since it is present on the connector but is reserved for the GND of the red video signal, and there is no corresponding red channel video signal pin in your picture. Maybe good to check that it does not carry any strange voltage but actually connects to the signal ground on the typewriter, in which case you should probably see continuity between the pins 6 and 7. Pin number 12 could be there for identifying a monochrome VGA monitor (old-style monitor ID bit 1, see at the bottom of this page for an explanation) unless it carries I²C.

As @pndc suggests, initial testing with an LCD display would be slightly safer than with a CRT, and — if it is a VGA-compatible signal and you get a picture — let you see the vertical and horizontal timings without a scope, since monitors will usually display these details in their OSD menus.

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    Given the age of device, unlikely it is VGA as per the connector and VGA as per the video signal, and definitely DDC was not invented yet so it won't have I2C. And you can't blindly split the video signal channel into three by just connecting it to all three RGB pins, it would be a triple load to the source and thus halve the 0.7V peak value to 0.35V.
    – Justme
    Commented Jul 1, 2023 at 20:44
  • Agreed, and with the points made as comments to OP. It's almost certainly doable, and there are fairly cheap signal converter boards available which help, but I'd add that a number of companies used "sync on green" which needs to be considered as soon as the problem looks like more than pinning.
    – Mark Morgan Lloyd
    Commented Jul 2, 2023 at 7:02
  • For the record, the converter board I was thinking of is the GBS-8100 which is available for about £20 on AliExpress.
    – Mark Morgan Lloyd
    Commented Jul 2, 2023 at 10:13
  • @zomega If your experiments with "new" screens work in the sense that you see a green picture, you could try to adjust the color completely down. Perhaps some adjustment on brightness and contrast, too, depending on the levels of grey involved.
    – the busybee
    Commented Jul 2, 2023 at 11:28
  • @MarkMorganLloyd Could you please explain what this board does? It has VGA in and VGA out. I don't really understand.
    – zomega
    Commented Jul 4, 2023 at 8:43

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