Disconnecting wiring bundles from sequencer box - part 3 - and commencing repairs

REMOVED THE FINAL COMPONENTS AND EXTRACTED THE BUNDLE

I was able to get the frozen screws on the contactor to loosen so that I could remove everything including the bundle. This I could put on the table and begin the repair work. 

Loose at last

As you can see, the sequencer box needs some serious cleaning before I reinstall any components or wiring. You can still see mouse bedding and the corrosion from excretions on the bottom 

INSPECTING THE WIRING TO DETERMINE DAMAGE AND REMEDIATION PLAN

I then cleaned and carefully inspected the wiring bundle looking for damage to the wires. I found a few wires with just a strip of insulation chewed off but the wire inside was intact; these can be repaired with heat shrink insulation. There were quite a few with more serious damage, even outright breaks in the wire. 

Wires chewed apart to improve rodent traffic flow through the hole

Several fuse holder had badly damaged wiring

Ground wire to convenience outlet was exposed

Serious damage on T1 primary wires

DEALING WITH THE T1 TRANSFORMER WIRES

The diagram for the transformer and the configuration chart for 240V power makes clear that some of the damaged wires are not needed for this machine. I chose to trim them and cover the end with heat shrink, as otherwise I would have chosen to find a new transformer as a replacement. This seemed to be an expensive alternative, but can always be done later if deemed worthwhile. 

Even more damage noted

Damage all to wire 1-6 side (primary)

I only need wires 1, 3, 4 and 6 for 230V configuration

REPLACING THE TERMINAL BLOCK (TB7) THAT WAS TOO DAMAGED TO USE

The block TB7 sat on the floor of the sequencer box, which exposed it to the acids of the rodent excretions. It was badly damaged and the screws holding it down were rusted in place. I chose to replace it with a new terminal block that is similar but not identical to the IBM part. My new block is rated for 600V and 15A, far above the requirements of the 24VAC transformer. 

My new block is slightly shorter, thus I had to drill and tap a new hole to screw down the replacement terminal strip. It is in place ready for transformer T1 to be wired to it and later the wiring bundle to connect here. 

REPLACING THE CHEWED FUSE WIRES

I cut and shaped new wire to match the damaged wires from the fuse holders. The old was pulled out of the bundle and the new temporarily alongside the bundle. Most had ring terminals on both end which made it easy to build them. One was soldered at one end onto a relay contact; I cut the damaged wire and left it on for now, with the new wire end routed next to the old. At a later point I will desolder the old and install the new wire. 

Damaged wire cut short and new wire end nearby

I used bright yellow zip ties to hold the new wires and the bundles together as I snipped away only a bit of the lacing. Once I have resolved all the wires that must be replaced, I will relace the bundle and remove these temporary ties. 

Twist ties preserving bundle until ready for relacing

I found a few wires with just a bit of metal exposed as the mice only removed a sliver of insulation. For those, I used heat shrink tubing rather than replace them entirely. I have completed the fuse end of the restoration. The convenience outlet fix will be minor and you already know how I am dealing with the T1 damage. The last big area to work on is the exit hole damage where there are at least six wires completely broken and insulation scraped off a few more. 

Fuses repaired, ready for reinstallation