On Friday 01 December 2017 12:18:35 Jon Elson wrote: > On 11/30/2017 10:20 PM, Gene Heskett wrote: > > I'm thinking its losing high side charging time because > > I've blown a chip. > > It could be a bad FET driver or a bad opto-coupler. It > might not take a lot of reverse voltage to harm the LED, and > then it would slowly weaken over time. Then, it could > become temperature sensitive. if you somehow got 12 V into > the PWM input, it could easily fry the LED in a second.
Very likely the bingo moment. In swapping out the bob, the none stranded wire came out of the connector, and I had to recreate that hookup from scratch. 12 volts into the pwm input has a high probability while I was function testing things, primarily because the new bob is not at all well marked at the terminal strips. The pwm should have been ok as that was the output pin I had to modify by getting rid of the relay, and jumpered the buffered pwm output to one of the relay terminals on the edge of the board. So once I had all the drawings in front of me, that part was easy. But in the process, lots of single strand easily broken wire got replaced by much more flexible stranded stuff, and the colors recorded on the drawings. One of the prices to be paid for the poorer short term memory as the years gang up on me. > > This is the second one I bought, about 3 years ago now. > > The first one, after I'd put a bigger toroid in the fwd > > leg, is still running TLM just fine. But I may have blown > > something in the inputs as I was trying to replace the > > bob, which had a long string of slow opto's with one that > > was all buffers with a 10 MHz bandwidth both ways, and had > > forgotten exactly how I had arrived at the 12 volt enable > > signal. I got that sorted eventually so I know I've got > > good signals to it. That 12 volts is from a wall wart, all > > it powers is this enable signal, and I measured it a > > couple times today while it was miss-behaving, and got > > around 12.9 volts both times, so that s/b ok. Regardless, > > can you repair it, and if so, the turn around time? I can > > paypal you the charges since its at least 99.9% my fault, > > and not exactly a new one now. > > Sure, I can repair it. I only HOPE it shows the same > symptom here so I can know it is solved. First test is the > "thumb" test -- do any of the chips get hot? if so, replace > immediately, then try again. When nothing gets hot, and the > 12 V current draw looks right, then start doing operational > tests. And whats the correct 12 volt draw? Perhaps thats why the warts output voltage went up about a volt, its an unregulated 9 volt supply according to the molded in label, and those are generally a bit over 12 when as lightly loaded as it is. I picked it out of the famous box of warts we all have because it would fit in the remaining space of the power strip I use for a main power switch. Everything else in the box was too big or wrong orientation to fit the space. Anyway, the connections and the signals are now correct on my scope. And the psu if I get on it could be a killer. DC 127 volts, and current enough to trip a 20 amp in the service box if it oscillates the spindle motor, or I forget to stop linuxcnc before I power it up. That power is slow started, tied to the machine enable button to initiate the slow start. 4 seconds later, it crowbars a 50 ohm 200 watt resistor in series with that stack of toroids. Too many microfarads in the supply, and a straight switch trips the 20 amp in the service. Draw is around 3 amps when its actually carving something. Send it to your addy in Kirkwood? > Jon > > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
