I assembled Dwight Elvey's KIM-1 debug board (thank you, Gary!) and have now certified two of my KIMs with it, so I'm very confident the harness operates properly.
Unfortunately, the one I *want* to repair, my original KIM-1, won't start up at all after replacing the 2102 RAM I was pretty sure was bad. I checked my soldering and found a couple spots without continuity that should according to the schematic, but fixing those didn't fix it. I also buzzed out the socket and found no obvious shorts, and a second 2102 equivalent from a second manufacturer has the same symptoms. I connected the debug harness and test 0, the initial "dead board" test, does show CPU accesses on the red LED and slowly flashes the green LED, so the CPU at least is alive and can access the test EPROM. However, test 1, the RAM test, should show long flashes of the green LED if RAM is bad. I was prepared to see all long flashes which might implicate the buffers or address decoder, but instead it won't blink the LED at all in that or any of the other tests. The red LED remains lit and appropriately extinguishes when the RS button is down. Again, the board works correctly and fully certifies the other two KIMs. What would cause it to hang (?) in the RAM test on the defective one? -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckai...@floodgap.com -- Roger Waters to moving crew: "Hey! Careful with those racks, Eugene!" ------
