Computers Overview
Commodore PET
Sinclair ZX80
Sinclair ZX81
BBC Micro
Sinclair Spectrum
Memotech MTX
    User Groups
    Video Wall
          DDFS PSU
          Reflex PSU
Memotech CP/M
Atari ST
DEC 3000 AXP
Raspberry Pi



The Memotech MTX Series


Dave's Video (Dwarf) Wall    

I managed to buy a load of Memotech Video Wall hardware off ebay in June 2013, and whilst it would not really be practical to build a full size Video Wall at home, I would like to see if I can build myself a Video "Dwarf" Wall (c), (for obvious reasons, I decided against just using the name Video Dwarf !).

The seller had bought the Video Wall hardware, complete with monitors, as a "working" system, although he had never tried to get it running and it lay gathering dust for at least 10 years before he needed to dispose of it when relocating. Unfortunately, when I tested the system, I found that it had a few faults, my efforts to get it up and running are going to be documented in this section of the website.


My Video Wall Hardware

Clicking on the links will take you direct to a selection of detailed photos on my Video Wall photos page.

Current Status

The MTX512S2 computer used to control the Video Wall system.

It looks to be in reasonable condition, but unfortunately, it is missing a couple of key caps, "3" from the main keyboard and "4" from the numeric keypad, the keyboard itself feels very good though.

The Video Wall Controller (DDFS), with the top cover removed, showing the 2 x 6" card frames for the controller and frame memory boards.

Faults : The Power Supply had failed - see here for replacement details

Ready for testing with the computer and Video Decoder

Video Decoder & Distribution Amplifier - 1

Faults : The unit powers up, but there are no outputs from the RGB video connectors. As I have other D/DAs, fault finding/repair of this one is a pretty low priority.

Video Decoder & Distribution Amplifier - 2

Status : This DDA is essentially working, the RGB outputs are not as "crisp" as some of my other DDAs, but I have not spent much time trying to optimise the various adjustments on the PCBs.

Video Decoder & Distribution Amplifier - 3

Status : The unit is working, outputs are present on each of the RGB video connectors and after doing a quick set-up, 7 of the 8 video outputs generate good quality pictures on the TV. A single video output on this DDA has problems displaying white text, displaying it as magenta instead.

Video Decoder & Distribution Amplifier - 4

Status : The unit is working, I have done a very quick set-up on it and now get acceptable video output on all of the RGB outputs.

The Reflex Controller

Faults : The Power Supply had failed - see here for replacement details


See here for the testing programme



mailto: Webmaster

 Terms & Conditions