Thanks Mark a few I had not found there - that CRT is the later H19 but, the 4k/8K RAM card is the one I have that has proven faulty and I do not have the schematic as they are supplied as a separate booklet I think which I do not have. I was lucky my 16K one was working as there is very little online but, I did find enough in this video to work out how to change the jumpers...
https://www.youtube.com/watch?v=zXcPWgkNLqo&t=590s
You are suffering the same thing as me it seems with adverts - any specific ads from the electronic mags that people have spotted would be great - it just seems that the fair number of issues I have on paper do not have any news or adverts - although each previous search including online I was not specifically looking. I may trawl the worldradio archive when I have a few hours to while away!
Anyway so this thread is useful to any other Heathkit computer owners you will rapidly come across the very active user group who have a sort of online archive:
https://sebhc.github.io/sebhc/
and an active google group:
https://groups.google.com/g/sebhc
I am going to see if I can work out why my 4K RAM is not working today -probably one or more of the 4Kx1 4044 RAM chips (it has new LS240 and each logic IC has been removed, cleaned and tested) they are helpfully called 443-832 by Heathkit but, they do list traditional numbers in the parts lists and in the pinout diagrams. Of course among the tens of memory chips I have there are none of them as spares...
I will say the the actual assembly Manuals are excellent - I was lucky to get quite a few with the machine but, not for all parts so lucky so many are online.
It was a real joy last night to get it running as the split octal display on the front panel is unusual - it shows high and low bytes of the address / registers as two groups of three with a third group of three for the memory contents. For its time the Front Panel monitor is really well thought out and super easy to use say compared to the MK14 - but then again it was six times the price...
They are not messing about with the 8v PSU capacitor either... the three rails (Other two are +/- 18v) are only half wave rectified and smoothed, cleverly the voltage regulators are on each card using the mounting rail as the heatsinks....
Over the last week or two - I actually took the big Cap out and proved it out on a bench supply slowly - the smaller two I just checked for no short. As it was linear I removed and unplugged all boards and then just powered it up with a Dim Bulb and checked the rails were all stable for an hour or so prior to trying each panel in turn.