After bad experiences with capacitors in the power supply of the TWIN terminal I decided to replace most capacitors in the main unit’s power supplies as well. With new capacitors the supplies work correctly. The +5V voltage was a bit low, but can be adjusted to its proper level.
The ECA unit uses a main CPU card with four 4K memory cards, two PROM programmer cards, a Debug card and a single secondary CPU with also four 4K memory cards. Sadly, a critical component is missing: there is no TWICE cable to connect the TWIN to a prototype. And since no documentation is available anywhere on internet, there is no way to recreate one. Fortunately the HM system did have a TWICE cable, and I can provide photos and circuit diagrams.
The photos below are before restoration and cleanup. The fixings for the front panel were loose, and someone used isolation tape to keep the front in place. A previous owner also tapped the +5 Volt line with a wire, which has now been removed. The fuse holder for the PROM programmer still needs a cap.
