[fasto]

I haven't been here for over a year. I got a bunch of extra jobs given to me last year and more or less stopped using the prototype shop.
Fast forward to now. Last week needed some parts made on the BMC20. Turned it on (it had not been used since December) and the batteries were dead.
I replaced the batteries, reset the settings, and all was well for a few hours. I ran a few jobs then shut down.

The next day I needed to run one more job. In the middle of the job, actually in the middle of helixing a circle, the machine just stopped moving x & y with the spindle turning. The console was totally non-responsive, even motion hold didn't light up when pressed. I e-stopped, turned off the main power, and removed the part. Then I powered up and got the usual "Executing Power Up Diagnostics" followed by a blinking cursor in the bottom left corner & nothing else, not even the console LED's lighting up for a few seconds.

Ah-ha! 1488 & 1489 troubles! Got my new supply of 1488 & 1489 chips and replaced the ones on the console board and the ones on the main CPU board. Powered it up, got the "Executing Power Up Diagnostics", then the LED's on the console lit up. We're cooking with gas now! Uh, not so fast:


Uh-oh, this looks like big trouble. I have to run right now. Later I will run a checksum on the EPROM's to see if any went bad. Beyond that does anyone have any thoughts?
I do have the 7.xx EPROM set left over from the 8.xx upgrade years ago that I can try.

[fasto]

Checksum on all 12 EPROMs matches the label so they're OK.
I thought I was on to something when I found one EPROM wasn't completely seated. No dice. Actually it's worse now. I'm back to one blinking cursor on the text screen and no LED flash on powerup.
With SW8 flipped on the display control I get all the symbols as I should when I press the buttons. Better yet the control shows the "EXECUTING POWERUP DIAGNOSTICS" on the graphics screen, and goes on to display that console communications AND the executive memory have failed.
I pulled all 3 dual-axis cards (remember I have a 4th axis) and the disk card (the floppy doesn't work anyway) with the same results.
When I pulled the memory card it does nothing so the power up diagnostics are on the memory card. I expected this.
I suppose that I'll try to remove the card extender to try the memory & CPU cards in the axis board slots in case the backplane is messed up.
I could probably replace all the 74xxx logic on the memory card & CPU card. I'll have to think about this.