Light Machine Corp. Benchman XTr (retrofit)

Thanks for the advice, Muzzer. Is there a way to definitively test optos on the board, unpowered?

Not really. But if you can power the board up safely and operate the optos you may be able to see if the output circuits seem to behave - easier said than done perhaps, unless you have the right equipment (eg an oscilloscope). I assume that you have homed in on this part of the circuit because of apparent loss of signals thereabouts. I've no idea what the circuit looks like, so couldn't comment.

I would recommend installing a machined contact IC socket in any position where you remove one of the DIP ICs. That way you can always remove it from the circuit in the future for more testing if it turns out that it is not the failed component. As long as J3, J4, J5, & J6 were not plugged in when you did the continuity test, you should be ok, there is nothing else in the LED circuits if they are unplugged.

I always tested them by removing the connectors and shorting the input pins to ground and looking for the outputs to change. For instance, short J3-2 to J3-3 and you should see a transition on U7-15 from +5V to GND when the short is present, and a return to +5V when the short is removed. Be careful not to short J3-3 to J3-4 as that is a direct power short.

Hopefully the replacement of these will go a long way towards making you toolchanger work again.

It looks like I've managed to make things worse. A lot worse. Last week when I was checking some voltages on J8 of the ATC board I slipped and shorted a couple of the power pins and ZAP! Smoked the TD62003 at U26 and since that's the gate driver controlling the air cylinders, those no longer do anything at all. Whereas before this little mishap the air cylinders would actually work at first (at least until the ATC lost track of what position they were actually in) now there was no signal getting to the cylinders. It also actually damaged the COM1 port on the PC that I was connected to. So COM1 on the PC is now dead ( I did a loopback test using hyperterminal and, yeah, it's gone.) So I went ahead and replaced all the ILQ5s, installing the DIP sockets as Don suggested, and while I was at it I replaced the TD62003 on U26 that got fried. But the situation is still the same: no movement with the air cylinders. I checked voltages on the inputs of U26 and get nothing when I try to operate the ATC in the software. So obviously no signal is reaching U26 from the eeprom at U4. If that power short knocked out my COM port (though I'm not sure that's really the case, as it was a little buggy before this happened) it could have fried just about everything else on the board in the process. I'm tempted to replace the EEPROM but I'm not sure what that would entail. Would the replacement have to be flashed somehow, and how would I go about doing that? And what about the microprocessor on U10? Would it be possible to replace that if need be?

What board is that? I think I have two of those. I'm not using them and don't know if either works. I'll check and if I do you are welcome to try them.

Wow! Thank you Steve.

Here's a photo of mine:


Is there some way to PM you here?