Repaired contactor and finished testing out sequencer box and some power supplies

PICTURES OF REPAIRED POWER SWITCH AND PROG LOAD BUTTON

I included pictures of the dummy light positions whose socket I swapped for the broken button. In addition, here are the Prog Load button and Power switch in their repaired state. 

CHECKED ALL CONTACT RESISTANCE FOR CONSOLE BUTTONS AND SWITCHES

While I had the console open to make the repairs above, I took the time to test every button for a good contact in both pushed and released states. The Prog Start, Prog Stop, Load IAR, IMM Stop, Check Reset and Prog Load were all near zero ohms for all contacts. The Console/Keyboard toggle switch was excellent as was the previous cleaned Power toggle switch.

REMOVED, CLEANED AND REINSTALLED THE CONTACTOR

I found clumps of rodent nest material between the contacts, between the parts of the contactor that should touch when activated, and in other parts of the component. I picked the all out and cleaned it up. After reinstallation, it is totally silent other than the actual clunk of activation, no buzzing like before.

JUMPED AT VERY LOUD TIME DELAY RELAY ACTIVATION

When the sequencer activates the contactor, it starts the time delay relay TD1 which provides the initial reset signal to all CPU logic until it kicks in after the delay. It also plays a role in protecting the machine if one of the three main power rails is missing - +6, +3 or -3. 

It is very loud with the sequencer box open, about as loud as the contactor itself. Thus, when I switched on the machine and was checking voltages produced by the raw DC power supply, and heard a loud unexpected clank, I thought something went wrong. Soon I realized what this noise was and was no longer startled by it. 

POWER PROTECTION CIRCUIT WORKING - LOCKOUT IF RAILS NOT GOOD

The sequencer logic card has three reed relays whose contacts are in series, with each relay energized by one of the main power rails. As long as all three come up to voltage and turn on the reed relays before the time delay relay fires, all is good. However, if one or more is not present, the machine shuts off the contactor. 

This situation also turns on another reed relay which stays energized to lock out the system. Flipping the power switch off and on will not reengage the contactor. The machine either has to have the CE switch flipped off or the plug pulled out of the wall to reset that lockout relay. 

Since I don't have the regulators wired up yet and thus have no power rails present, the card is doing its job to shut down and protect the precious circuitry. During the time delay from turning on the power switch until TD1 energizes, I could check all the voltages on the power supplies and fuses. 

TESTING PRESENCE OF 230VAC AT ALL RELEVANT FUSE HOLDERS

Everything is looking good with the power sequencer box and the wiring. I put in fuses to each circuit to check out their operation, except for two that I can't test yet. The convenience outlet fuses won't get power because of the frozen, defective relay R3. The fuse for the SMS connected peripheral AC power requires that transformer T2 be wired in to drop 230V down to 115VAC for the peripherals such as the typewriter motor.  I don't have T2 connected yet because it also will spin the cooling blowers. 

TESTED RAW DC POWER SUPPLY

I put in the fuses for the raw supply and verified it is putting out the raw voltage, around 8V, that will be regulated down to +3V and -3V. These are two different outputs, one per regulator. A third circuit produces around 12V that will be regulated down to 6V for the third rail. The other side of the raw supply produced +48V and +12V, actually slightly higher which is normal. 

TESTED LIGHTING DISPLAY POWER SUPPLY

The many lamps in the display pedestal are powered by 7.25VAC from a beefy lighting supply that has its own fuse on the sequencer box. I validated that the proper voltages were present in the display box. 

FINISHED LACING THE FUSE WIRING AND CLOSED UP THE SEQUENCER BOX

With the fuse holds in place, I manipulated the wires which include a few I had replaced due to rodent damage. When I had them formed in the correct bundle shape, I laced them up to return them to a state similar to how IBM built the machine. 

The box can be closed since all fuses and the circuit breaker are on the outside and don't need access. I will open it again when I do a couple of deferred repair tasks later. I am deferring expenses until we determine that the machine is in reasonable health and likely to be fully restored. 

CLEANED BLOWER AREA IN PREPARATION FOR SPINNING THEM TOMORROW

I hooked up transformer T2, which drops the building 230V supply down to 115VAC for use by the blower motors and various peripherals which use 115VAC motors. Before turning on the machine with the blowers in the circuit, I wanted to make sure I wasn't blasting dirt, nut shells and who knows what else into the logic cards and power supplies. 

When removing the nesting material from the contactor earlier, I found that some of the gnawed strands of wire were mixed into the bedding, making it very capable of shorting out pins and components. This had to be cleared from the machine before first blowing air through the machine. 

COUPLE ITEMS TO ADDRESS LATER IN THE SEQUENCER BOX

I found that relay R1, circuit 1, had a resistance of 93 ohms when the relay activated to connect the common to the normally open contact. This adds relay R2 coil in parallel with TD1's coil. I suspect it will be good enough to fire R2 which is what delivers +12 and +48 to the machine when the power rails are verified to all be present. If not I can go back in earlier and burnish the contact to lower the resistance but since it probably will work okay for now I will wait until I am working on the relays later (see below) to handle this. 

Relay R3, which should be activated whenever the main circuit breaker is turned on and T1 is producing +24VAC, is frozen. It's only purpose is to connect the 230V from the circuit breaker output to a pair of fuses (F3 and F4) and through them to the primary of transformer T3. T3 drops the voltage to 115VAC for the convenience outlets in the 1130 and its larger peripherals. 

The convenience outlet is unnecessary for operation and served as an alternative to wall outlets which don't exist in computer rooms. The museum where it will be exhibited will have wall outlets, thus this is not essential. As long as I can repair R3 or replace it at a modest cost, I will do this just to get the 1130 as close to factory condition as possible.