On Thursday 02 January 2020 15:59:09 Gene Heskett wrote: Reposted with some spelling corrections, clarifying language, and a thank you I forgot.
> greetings & a happy new year to all; > > I finally figured > I felt good enough to go out to the garage and see if I could resurect > the 6040. When last putzing with it I had left it with the circuit > from machine motion to lights and coolant pump, and the mist pump > disconnected from the 7i76D field output 0 & 1 and was in between > sessions in the cath-lab fixing my ticker. > > One of these two was (I first thought) a dead short on the 12 volt > field supply, and when I traced the wire to the lights & motor coolant > relay, I found that I'd not installed a flywheel diode across that coil > because I was out of a suitable diode. So I ordered a bag of 100 volt > 4 amp diodes. > > While I'm keeping this chair warm, they came in, so I went out and cut > a 40" piece of light zip as that was more suitable wire, crimping a > diode into the hilitchi sleeves, pulled that relay loose and connected > it, throwing the other end of the wire toward the interface box. Moved > the ladder and hooked the other end up. > Cycled it on and off from linuxcnc several times, worked perfectly. > Hooked up the mister motor power again, and it worked as designed > after a couple minutes to reprime the pump as it had a good month to > bleed back. > > By then my legs are telling me they are going to give me hell for > cramps in the night, I've been laying around too long. > But a tum calcium pill in each cheek headed that off. > So thats the background. > Question for Peter: > Could the lack of that diode have triggered a substrate scr in the > 7i76D?, crowbaring the field power in the 7i76D, but which due to the > supply trying to cycle, never got clear to zero volts to reset that > invisible scr. > > Any other failure external to the 7i76D would not have been a short. > It could only be healed with a full powerdown, which is the only > theory I can come up with that makes sense. That same 7i76D output, now > with a flywheel diode seems to be running it flawlessly now. The > supply is rated at 12 volts and 2.1 amps so doesn't (probably) have > enough cajones to burn things up. All relays on, its a tad under an > amp total. I have seen this only 2 other times in my 70+ years of putting electrons to work. Thanks Peter. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
