Drat - error in my new PCB for 1627 controller card

STOPPED DEBUGGING THE BODGED CARD ON THE BENCH

Mostly the card was working correctly but I would continue to get flakey behavior that after investigation seems to be issues with the bench testing apparatus itself. The only issue that was still occurring was quite odd. 

When the system reset (DC Reset) would stop, the request for interrupt on level 3 (IL3) would immediately go on, but this was not because of any of the six movement commands being activated. If I monitored the DSW Bit 14 (busy) signal using a pullup resistor, the false triggering of the IL3 stopped! 

There is no logical connection between these other than possible shorts or power interactions through chips. It doesn't make sense from the design thus I had to ascribe it to an issue with the particular card I am testing - the bodged up one with jumper wires to the donor SLT card. 

BUILT NEW SLT CARD WITH INTEGRATED SLT CONNECTOR

I soldered all the components onto the new version of the card which has an integrated connector, avoiding the requirement for donor cards or jumpers. 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. 

It was time to install the housings on the end of the cards. I have not completed the new 3D printed housings, but I pulled two off of the donor SLT card I had been using for the earlier instance of the plotter controller card. 

DISCOVERED BAD SPACING BETWEEN THE TWO CONNECTORS

One housing fit but the other will interfere with the first if I try to install it. I compared it to the spacing of a normal double width card and saw that my layout for the PCB was wrong!

You can see in the picture above that the left row of contacts lines up with the openings in the housing but the right row of contacts is over too far to the left. The width of the space between the connectors is too small in my card. I measured the spacing on an IBM double wide card and found that the middle of the contacts on either side should be .375" apart. 

In addition, there are small tabs on the IBM SLT card that lock the housings onto the card, so I should be implementing them as well. 

Back to the drawing board (well, back to KiCAD) and another round of PCB manufacturing.