The team has been generating some reference material which document various aspects of Computer History Museum's IBM 1620. Available are:
Pre-Power Up Tasks
Several quick checks have been done over several portions of the machine, but one complete and careful check should be made.
The correct jumpers have been determined and verified, they just need to be moved. In the process it was found that all of the main core memory thermal switches are bad.
We have a clearly defined procedure for thoroughly testing the power supplies. The -36v supply, the +12v supply, the +30v supply and one of the two -12v supplies are fully tested and are ok. The other -12v supply had a problem which was traced to be two bad transistors. After replacing the bad power transistor (with a vintage 108 that Tim donated) and swapping regulator cards, the supply seems to be ok. The regulator card will be repaired (with a Tim supplied 026 transistor) and then the power supply will be throughly tested. Preliminary testing of the unregulated +48v supply found it producing ~65vdc - more work is needed on it. Some testing of the other unregulated supplies (24v, 3v margin) also needs to be done.
This task is not needed for bringup and is very low priority since we don't have a master 1311 disk drive at this time.
This task is almost completed.
A replacement V-belt has been ordered.
I plan to ask a professional office machine repair person to help with this.
The loaner typewriter has arrived in good condition and with all cables & connectors. It just needs to be plugged in.
No word yet on the air filters.
Tim has explored this and it looks like a lot of work to rejumper the machine for 20,000 digit operation. Since we may be restoring the 1623 Extended Memory Unit, it may not be worth making this change.
As a result of the survey of SMS card in each of the logic gates, 10 previously unknown card types were found - ARW, AYX, DEQ, DES, DEW, DFB, DFC, DFE, DFG and DFP. Their function needs to be determined.
While debugging the thermal chain, we discovered that all three thermal switches and the fan in the core memory are bad. These need to be fixed in order to power up the machine.
Tim has studied the entire power sequencing logic and has created a detailed "bring up" plan.
This is not needed for the main restoration work but to safely preserve one of the 1620 artifacts.
Remember to document everything that is done to the machine.