IBM 5406 System/3 Restoration 2021


Dan and Alex went to Arlington and picked up the System/3. Unfortunately in the confusion the sheet metal panels that go on the processor cabinet next to the desk were left behind, and were scrapped. We can make some replacement covers out of painted plywood, and it will look fine.

We received a large stack of the original IBM documentation that came with this machine, a CE disk pack, and a CE cassette for loading disk diagnostics.

The disk is a 5444-1, the low density version. By moving a microswitch in the drive, changing a jumper on the disk controller backplane, and reformatting the fixed disk and any removable disk packs, we could change it to a 5444-2 and double the drive capacity.

We did an initial assessment of the system. It is complete and mostly in good condition. The printer will need a new toothed belt that drives the ribbon shaft, and the rubber pinch roller that drives ribbon. The modern replacement, if we could find one, is made from urethane instead of rubber.

It will take some studying to learn about this machine before we try to power it up. Fortunately there are quite a few enthusiasts around the world that can help.

The flexible drive rack, at the bottom right, is to advance the ink ribbon and is falling apart. I can't find a source for the original IBM parts, so maybe we can make a new rack from a nylon timing belt.

This is the rubber roller that moves the ink ribbon. There is almost nothing left of it. We might be able to find a substitute, or have a new one made.

This is the power connector for the whole system. The connector is made by Russell and Stoll (now part of Thomas and Betts). It is part number 3913 and the mating receptacle is part number 3743. We ordered a New-Old-Stock receptacle from eBay. This connector means that the system is wired for 208/230VAC single-phase and needs a 20A circuit, so we will be able to power it up in the warehouse or the Lab space.


We received the Russell and Stoll receptacle from the eBay seller. Unfortunately they sent us a P/N 3754 instead of the P/N 3743 that we bought. We will try again to find a P/N 3743 so we don't have to modify the power cord.


Connor K. is looking for a bevel gear that connects the knob at the left of the 5213 printer to the tractors for the paper because his broke. It looks like it is item 221 in figure 4B in the parts manual, so it is P/N 2525706. There is a note on the parts list that says that this part is only used on the 2213 printer. We looked through our mid-range systems inventory, and we don't have a new gear.

We made sure that the paper tractors in our 5213-2 printer were free, and gave the paper position adjustment knob a twist. There was crunch, and the knob turns freely without moving the tractor. It looks like our bevel gear broke too. Time to print a new one.