The first and original Scottish Region four character display

During my time in the rail industry a colleague collected a large number of Train Describer display modules ranging from early 60's displays through to 00's including all the ScR displays. When I started to write up the web pages about the ScR Electronics Section he gave me the box so I would have an example of each of our display modules.

One display was missing from the collection and that was the original Hot Axle Box Detector display. We had a few photos and I found a blank PCB but that was all. This display was used at Motherwell Signalling Centre for the Auchengray Hot Axle Box locator. The first in-line display for Hot Box Detectors, until then the locators/displays were housed in a panel extention at the end of sixth control panel.

The display re-surfaced in 2022 just at the time I was packing up my workshop so back in its box it went and now it's time to bring it back out, switch it on and see what happens.

This was the very first four character display designed and built by us back around 1981 and as it's original use was for a HABD display we were trialling different colour 5x7 dot matrix displays. Train Describer (TD) displays in this period were High Voltage Tube type which displayed characters in green so we considered whether red should be used to differentiate its use for the Signaller. In the end red we used the red LED's.

This display hasn't been switched on for well over forty years and I see the EPROMs haven't had there windows covered so it was fingers crossed when switching on..

So it is obvious that the right hand character is missing the bottom row so a quick look at the interboard wiring shows that some wires have been squeezed together and that one wire has broken off. A quick solder later and the display is fully working.

For me it was interesting to compare the character set to the display I recreated in 2021, firstly the original display has the characters for the HADB which the new one doesn't. It also has our first attempt at animating the characters to make explosions, space ships etc.

The original and the recreated boards sise by side.

I took the opportunity to recover the data from the 2716 EPROM.