Pertec ddrive issue appears to be simply a bad fuseholder

PERTEC D3422 DRIVE RESTORATION

The +5V Timer board, which was undocumented, was one area I needed to investigate during my debugging, so I traced out the circuit, drew a freehand schematic and labeled the board layout. I also made it available to others who may be working on Pertec disk drives with this optional feature.

Mostly hand-drawn schematic of timer board in Pertec drive

Board with components labeled

I removed the defective fuse holder and prepared the power supply for a replacement part. The fuse wasn't blown, it just wouldn't maintain a closed circuit so that the -20V raw supply never made it to the rest of the circuitry. I am feeling better about the condition of the Pertec drive as a result.

DATACENTER SHED CONSTRUCTION

I moved a few items into the datacenter shed to make room in my main workspace. I need to elevate the Pertec drive on a stand where I can put in the intensive time and gain access to all sides easily.