Quite unlikely you'll find this. However, most switching power supplies follow common designs, and if you look up the ICs reference you might find reference designs in the datasheet or application notes that are close to it.
As for zener diodes, you can usually test them in-circuit with the multimeter in continuity mode : as regular diodes they'll pass one way, and not the other way, since the zener threshold isn't met for it to pass in the other way. Testing the actual zener voltage wouldn't add more I think, usually they just fail completely, either break or pass always.
Sure the capacitors are ok in there?
What's the symptoms?
You didn't specify which zener… but anyway they all seem to have whatever reference they have on the side facing the board so not very readable anyway.
I just noticed on mine R2 has its heatshrink tube is quite burnt.
The stuff around the Triac on the first board (the one with the fuse) is odd. I don't think it's PFC, those weren't a thing back them. It could be overvoltage protection, some use a zener to control a thyristor.
Issue solved, after removing and testing the zener (ZD1) and confirming it was shorted for good, i was able to read the tiny reference.
Was a 18V Zener diode, removed another diode nearby as well, still good but as the PSU was in pieces already…
I connected the PSU to a IIsi and it fired right away.
Great, so I can put mine back in one piece
Someday I should recap it maybe, and check this resistor which I think is quite burnt. I noticed someone posted the cap values elsewhere here.
At some point it'd be great to get scans of the PCBs and pictures to RE the schematics for further repairs…
I really hate opening these units. That stupid two-board sandwich design and the fiddly enclosure is not great to work with. I am converting one to use an ATX PSU inside it and it's going to be a lot neater that way.