Finished AC rewiring, had an issue with the console light power supply that needed addressing

COMPLETED TB-1 WIRING WITH MODIFICATION

I implemented the split where the fans are grouped on the 230V line, jumpered over to the section of the terminal block for 230V, while the 115V output of T2 is reserved for the 1053 typewriter motor. Or so I thought - more later. 

COMPLETED TB-2 WIRING

Similarly, I finished putting the TB-2 wiring inside the power distribution box back to its original layout. This involved tracing every wire with the continuity checker to be sure that they were all in their correct places. 

DISCOVERED THAT THE DISPLAY PANEL LIGHTING POWER SUPPLY IS 115VAC

Having restored the wiring for the 7.25VAC power supply to the circuit fed by fuse F7 and having a suitable low current fuse in place, I turned on the machine to verify the lighting voltage was present. Nothing. In fact, the fuse blew!

I looked at the diagrams to see if this was wired improperly or was set up for 230V. That is when I noticed that IBM didn't provide the ability to switch the supply between 115V and the higher voltages. Instead, they ship either a 115V supply or a 208/230V supply. Reading the part number quickly confirmed that it was the low voltage version. 

IT APPEARS THIS MACHINE WAS ORIGINALLY CONFIGURED AS A 115V SYSTEM

This explains a lot. No wonder I didn't find the Ferro Resonant transformers used by IBM, instead finding some low capacity alternatives in place. When a machine is ordered for 115V, IBM does not include the transformers as there would be no need to step down voltage. 

A prior restorer converted this to 230V, adding the transformers and swapping all the fans to 230V versions. That left the AC wiring inconsistent with the wiring diagrams and usual IBM practice.

MODIFYING THE TB-2 AREA TO SUPPORT THE LIGHTING SUPPLY

Since transformer T2, normally providing power to fans as well as the 1053, is underutilized right now, I found a scheme that would let me move the lighting power supply over to the 115VAC fed by T2. This involved adding a metal jumper and moving a couple of wires around on TB-2.