Installed 2501 controller cards in 1130, beginning debugging

FOUND ONE CARD WITH A BROKEN SOCKET PIN

A 3421 card, which is simply ten inverters, had one of its circuits failing when I tested it with the 1442 reader. I put it aside but need it now that I am adding in the last of the device controller logic groups, the one for the 2501 reader. I put it on the bench to verify the failure part, expecting that the issue would be a component on the card that needed replacement.

What I found instead was that the springy contact material inside the socket of the card had snapped off for one pin - the failing inverter's output. This card had a plastic socket cover that was mangled up, which apparently allowed the pin to be bent and damaged in a prior lifetime when it was inserted into the card compartment. 

These springy contacts are covered by a plastic shroud normally. I removed the shroud to assess and replace the contact. 

REPLACED THE SOCKET CONTACT PIECE

I took one of my junk SLT cards and removed the contact from it. Apparently these are soldered onto a pad on the PCB making up the SLT card, allowing me to neatly remove it and attach it to the 3421 card I am repairing. 

Salvaged contact from a junk SLT card

Contact soldered onto the repaired card

ODD BEHAVIOR WITH THE CONTROLLER CARDS IN PLACE

Bit 10 of the Accumulator (ACC) register and bits 10 and 11 of the Accumulator Extension (EXT) register were permanently on. I tried executing a shift instruction but the bit didn't turn off. I believe something is pulling down the output lines and of course the likely suspect is one of the couple dozen SLT cards inserted for the 2501 controller logic. 

Bits 1 and 3 in the EXT were loaded by an instruction, while the 10 and 11 are spurious output that stays fixed.