Sunday, July 19, 2015

Done with DOS/VS, digging through Pertec problems, and repairing Nixie/Dekatron clock


I finished up my DOS sysgen tasks to my satisfaction. I have the listings of the libraries and other contents of the fully functional DOS/VS 34 system, having done various tasks such as deleting unneeded programs from libraries. Now I can move back to VM/370 on the P390, abandoning the Hercules simulation on Windows and running on a 390 processor chip.

Listing of the disk pack holding my generated DOS/VS system

I discovered that my -20V raw supply had blown its fuse again, which was the reason that the solenoid lock wasn't getting full power. Surprising that the logic seemed fine with this, lighting the safe light and spinning up the system, but in any case this isn't good. I am a bit concerned that I might have a high number of failed components, but will soldier on working problems as I found them. At least, for a while.

There is circuitry to verify that all regulated power supplies are operating at normal levels, which I would expect to be a show-stopper for trying to spin up and load heads. This is going to require some probing and voltage validation before I next try to load heads on the drive.

The -20V supply fuse holder itself is not in good shape, which is contributing to the problems. I have another on order and will swap it out. When I replaced the fuse and powered up, I saw a blip on the -10V regulated line before it went to zero (from a newly blown fuse). I thought I had been back to basics and had a solid power supply situation, but that changed in the last day or two.


I found the high voltage supply section was not working - I pulled the two small and one power transistors and found that while the power transistor survived, the two smaller ones had failed. Replacements are on their way in a few days.

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