Help asked re early V late schematic and interpreting adjustment procedures?

[Chris Wilson]

I have two elderly Farnell linear power supplies, one was in poor condition and exhibited some faults from time to time. With the forums immense help I have now fixed it, but wish to calibrate its various adjustments. The issue is I have schematics for both the earlier type, which I do NOT have, with all discrete components on the three PCB control boards, and schematics for the later versions, which I DO have, with some IC's on two of them. The only manual I have been able to locate refers to the early boards. I have managed to crack adjusting max output volts, and max output current, for which I converted the instructions for the earlier model's adjustments to reflect my own, as best I could, and both were quite a bit out...

I am now pondering how to work out what P1 and P2 do on the SCR board I have, as the manual discusses, as far as I can see, a board with 4 pots on it. My board has just two multi turn pots. I want to adjust the "separation voltage" on the SCR board, that appears to adjust the relationship between the main transformers secondary voltage, under SCR control of the primary, and the output of the pass transistor assembly. The idea is to keep the energy dissipated in the huge pass transistor heat sink tunnel as low as possible.

If anyone's up for more cross checking of the early and late schematics, and the "Internal Adjustments" section of the manual I will attach them as .jpg screen shots. If I could work out the function of P1 and P2 multi turn pots on the op amp inputs of my late type SCR board and check and reset the separation voltage I'd call it a day with calibrating the brute Thanks for all the help so far everyone!

[Chris Wilson]

And here's the description of how the early version of the SCR Control Board should function: