BUILT NEWEST SLT CARD WITH INTEGRATED SLT CONNECTOR
First I used my hot air rework to remove all the components from the earlier PCB, including the gold spring contacts. Since that card had too narrow a spacing between the two connectors, I had to build another version of the PCB. Too, the spring contacts were so wide that they were hard to line up properly when soldering to avoid shorts. I found and bought some new narrower contacts and redid the PCB.
I soldered all the components onto the new version of the card with its correctly spaced integrated connectors. All the spring contacts are in place on the card so that it can connect to the pins in an SLT card socket, either on my bench tester or more importantly in an IBM 1130 card compartment. The solder pad helped pull the contacts into good positioning on the edge of the card due to the surface tension while the solder was molten.
I installed housings on the card to cover the contact and to guide the card into the SLT card slots. It fit well into the bench testing socket now. I conducted some tests to verify that the signals were delivered reliably.
QUICK BENCH TEST TO VERIFY NO SPURIOUS IL3 TRIGGERING
I leveraged the test setup I had in place from testing the prior card versions. The key here is to see that IL3 is not triggered by a power on reset, only when an XIO Write is issued with at least one of the motion command bits set.
CARD NOT LATCHING INTO SOCKET (SLOT)
IBM SLT cards lock into position in the slot due to some fine features of both the board (backplane) pins and the card contacts. I was hoping that the pressure of the spring contacts alone would give a reasonable anchor for the card but it slides up and out of the slot when released.
The pin on the board has a notch or hook at the end, looking a bit like a crochet hook. The contacts on the SLT card have a bend that will fit into the notch to hold the card in place.
Notice that the IBM contacts are bent at the rear and have their active contact point towards the front of the card where it enters the board socket. Thus the pin with its hook slides over the end of the contact and resists its removal. This produces a nice 'click' as the card is inserted and requires a bit of force to begin the extraction of the card.
The replacement contacts I use don't have the same shape, one that was designed to interface with the hook on the end of the board pins in the socket. My contacts and the pin both deflect a bit as I push the card into the socket but they don't reach a position where they are held down, instead the deflection acts to push the card back out of the slot. It is not a strong force, but even normal vibrations would cause the card to walk out of the socket. I will have to figure out an anchoring method if I am to use these alternative boards and contacts.
FOUND CONNECTOR FOR THE REAR OF THE IBM 1627/CALCOMP 565
I located a Cannon connector that will fit with the back of the plotter. I can manufacture a cable that connects this connector to a smaller 8 pin connector that will plug into the rear of the 1130 gate A with a matching set of connectors I purchased for that purpose. Three pins on the Cannon connector are powered by AC from an SMS power card, the reset are signal lines going to my new 8 pin connectors.
The bill of materials for the replacement 5806223 card is around $85 not counting tax and shipping for the components. The cost for the new cable with its connectors will be around $50. When I solve the anchoring problem, hopefully without having to grab the IBM contacts from donor SLT cards, I can proceed to test this new card in the 1130.
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