DID A SIDE BY SIDE COMPARISON OF NEW ZENER TO THE ONE IN THE REGULATOR
I grabbed a zener diode from my parts cabinets and did A-B comparisons on the curve tracer to more accurately determine the voltage for the part. While I had believed the diode was 4.5 volts, I found that a 4.7V part exactly matched the IBM part. It even had the same slightly slow turnon, not rising vertically but on a slight slant, something I had suspected was an issue with the IBM part.
EXPERIMENTING WITH MY CIRCUIT SIMULATION TO GUESS AT FAILED COMPONENT
The circuit simulation is running well on CircuitLab, although the parameters of the transistors are not accurate enough to support operation with a full 20A load yet. Basically the default transistors, low current models like the 2N3906, wouldn't be able to drive enough current to maintain the voltage under heavy loads, whereas the actual transistors used in the supply certainly can do this.
SHOP MOVE AT END OF MONTH
I am moving my workshop to a different address, not very far away from its current location, partly to support the Chiropractor next door who is desperate to expand into my storefront. The new place is being prepared with a new air conditioner and 240 service thus the exact move date is still a bit hazy. The Chiropractor will move my equipment and supplies and since he rents the storefront as of May 1, the precise date of movement is not that critical.
TRAVELING TO SPEAK AT VINTAGE COMPUTER FESTIVAL EAST
However, between now and then, I am traveling to speak at the VCF East event and once I return it will be the final week before the move, so I have to suspend work on the 1130 and finalize all the packing beginning today. I put all the covers back on the 1130 and prepared it for safe movement, with only the disk drive being moved separately.
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