Update
Wow, was it really May 2021!
Anyway, yesterday I finally got the machine on the bench, physical condition maybe 7/10 a lot of surface corrosion on the chassis, and some of the plating on the controls panel is corroded.
I had made a bulk purchase of 10uf 50V capacitors recently, so I was armed and ready for battle. The cost of Tantalum capacitors is sufficiently high now that I decided to use standard 105C Aluminium Electrolytics, reasoning that more modern components would be of at least a similar quality as the original 40+ year old components.
I didn't even bother to power the machine up - immediately replacing all of the 10UF capacitors on the main board, the LAT and the STT board. I also replaced the 4.7uf capacitors on the print driver board (using the same 10uf capacitors)
This all took a couple of hours, and the boards look reasonably neat even though the true components have not been used.
I decided to power the machine up.
POP!
Oh dear, a rather loud death like noise came from the power supply, interestingly, no smoke.....
Quick post mortem on the PSU found the main bridge rectifier doing anything but rectifying, so having a suitable replacement in stock, this was fitted.
Decided to meter out the main reservoir capacitors (Called "Ears" as Henning said) - resistance readings looked to be about right, so I tried running them up on a bench power supply, this told me a very different story - Capacitor 1 (on the RED wire) reformed quite well at 250VDC showing a leakage current of 1.7ma.
Capacitor 2......
45V applied - Bench Supply tripped.
Okay, try again..
35V applied - hmm, 560ma leakage current.....
Okay, so that is past it's use by date.... Much grumbling and groaning - these monsters are probably unobtainable, or expensive, or possibly both...
Stopped work on PSU.
Fitted spare PSU from other machine in workshop (known to be working) Hmm, now not working..... Ah, fuse in rear panel of machine.... replaced... Aha! Machine powers up.
Time to connect the telegraph tester.
Now, being British, we do not like using handy European colour schemes for cables, and being Military, we wouldn't use an easy to find connector either....
So, the Socket needed to mate with the original connector is : Cannon C2092 12 10 FNO
Connections as follows
Pin B RXD-
Pin J RXD+
Pin D TXD-
Pin C TXD+
.
With the test set connected, oh, and the cover switch defeated (Thanks for the tip Sebastian) the machine burst into life.
Once I have cleaned the case up and had a bit of a tidy of the warzone that is my workshop, I will post a couple of pictures, and some video.
The machine works at all speeds, 50, 75 and 100 Baud
Parts for the PSU arrive tomorrow, lets hope that is a simple fix..... More to follow.