Thursday, August 21, 2014

Final power conversion checkout and first power testing of the 1131, plus miscellaneous tasks

The reforming of capacitors and testing of the PS supplies were done with it wired for 115VAC inputs, since the variac we had was not rated for 230V, so there is a recheck required once the PS drawer is reconnected to the machine. This will verify power from the input plug up to the output of the PS supplies, the 7.8VAC lighting supply, the 51VAC meter supply, and the 24VAC sequencing power developed inside the power sequencing box.

Power supply ready for re-installation
I bolted the PS back in and reconnected the two dozen leads to the two terminal strips. I then turned off all the circuit breakers and removed all the fuses, so that I could walk the power through the system carefully step by step. Step 1, plug the input plug into the 230VAC supply. Verify that we have supply voltage at the input to the main CB. Good so far.

Step 2, turn on CB1 to see power delivered to contactor but nothing else, verifed by testing that there is infinite resistance on the output leads.  This didn't turn out so well, because the CB wouldn't click to a fully on position. It sat in the tripped position or went to off, but never engaged.

I have a bad main circuit breaker, which stops me from moving any further. I would have brought the 24VAC sequencing circuit power online next by inserting fuse F5. If that worked okay, I could try the power on switch which should close the contactor. Alas, I need the breaker replaced before I can do anything else.

Opening waiting for power supply installation
Some of the connections that had to be restored
More power supply connections to restore
The blister (extension on the left of the keyboard that holds expanded storage configurations (>8K words of core) wasn't aligned satisfactorily, leaving an uneven gap on the top and mating askew on the front. I loosened the attachment brackets and shifted things until I was satisfied.

I checked the disk drive for compatibility with the 230V mains (incoming power) I am going to use. I did this two ways, by investigating the options listed in the official 1131 parts catalog and by inspecting the motor specification plates. The results from the parts catalog shows that 60Hz machines use 115VAC motors powered through the stepdown transformer if the mains are 208 or 230, while 50HZ systems use 220V motors. The ALDs for the drive just refer to "AC voltages", as do the installation instructions for the drive. Finally, the motor itself had a plate listing 115VAC 60Hz, which is definitive.

Stepdown transformers on right and above out of frame, power sensing relay board at left
The console typewriter (a modified 1053 printer) had its shipping bolts removed and I began inspecting its condition. Since virtually every Selectric or Selectric-based device found today which has sat idle for even a couple of years will have had its grease solidify and its oils gunk up with atmospheric dust, I can be certain that I have to clean and relubricate the mechanism before I power it up and try producing output. My initial visual inspection shows it gummed up, although not as bad as the worst machines I have seen, but still requiring replacement of lubrication before it is operated.

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