Greetings; That SKU-47158 schematic is conspicious by its incompleteness.
The arrows labeled A,B & C are in fact interconnects to the brains of this servo amp, and which are not shown. Note that a bipolar driving waveform presented to C, referenced to that circuits ground which is the center of the +12 and -12 supplies at the bottom of the page, will turn on first one, then on the opposite swing, the other of the opto-isolator stages, in turn driving the gate of the MOSFET actively either to ground for a turnoff, or to nearly +18 volts for a very solid turn on of the MOSFET. Nothing is shown on that schematic to effect that style of drive, so it has to be all part of the A,B & C connected stuff that is on the card, but not shown on the schematic. The .33 ohm resistor would appear to be the fault detector sense resistor via U5a&b but I've not traced that out, and it does work. It would appear, since the MOSFET has a 20 amp rating, that the power limitation this VSR can handle is fixed by the diode bridge as it has only a 4 amp rating. The possibility of replacing it with a 10 amp bridge, and the fuse then with a 3 or 4 amp fuse would appear to give it a bit more headroom for shorter jobs, but the motor would need more active cooling for jobs that ran over half an hour or so. This servo, when it worked, has an extremely tight speed regulation, so tight that I had to put an ammeter into the motor circuit to see how hard it was working as the slowdown from running free at .2 amps at full speed, to 1.5 amps of draw, still at full speed resulted in a speed sag of less than 1%, the ear was hard put to detect that slowdown before it blew a 2A fuse. This is the orignally purchased machine: <http://www.siegind.com/Products/br-x1-lathe.htm> I went to the SEIG site, and tried to leeave a message but got a box full of pictographic chinese with a 500 in the middle of it, so I tried to 'contact' them but the only email agent it wants to use is Evolution, and I use kmail here. Does anyone know where, in FF3b4, or in Fedora 8, the definition of what to do when the link I click on in FireFox3b4 starts with "mailto:";? I had that fixed once to use kmail, but some so-called update must have blown it away. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) No two persons ever read the same book. -- Edmund Wilson ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
