On Saturday 10 October 2009, Hubert Bahr wrote: >Gene > So you have the X-1, I have an X-2 and X-3 also from Habour >Freight. I am guessing the principles are the same but I will need to >check the implementation. Specifically, I am interested in what you >connected to pins 1, 2 and 3 of PMDX-106's J2, the spindle signal >connector. Specifically it states that pin 3 should not exceed 15 volts >or you use either a +5 or +10 volt PMDX supplied reference. It looks >like the G540 has similar capabilities but it is limited to 12 volts >instead of 15.
The PMDX-106 can use the reference from the G540 if its limited to 12 volts, and will source it to the PMDX-106. So that isn't a problem. Or are you saying its maximum input is 12 volts? In that case, I'd use the 10 volt source and turn up the gain in the G540. >I am surprised you say that the voltage across the pot >is ac, how could it be used a speed reference. Not sure, I looked at it with my multimeter set to dc and only got a few hundred millivolts across the pot, but when set for AC, it was quite erratic, reading 2 volts on one sample, an 8 on the next, etc. So I assumed it was a pretty non-symetrical AC feedback and didn't attempt to further analyze it. >I guess if you hooked it >up as figure 7 it wouldn't matter. I don't have figure 7 at my fingertips, those docs are out in the shop and its way past the witching hour now. I'd assume that is using the PMDX-106's 3 terminals as a direct replacement for the pot in the VSD? >I could see it as being AC >referenced to ground but not across the pot. But if necessary I can >hook up my Tectronix purchased new in 1973 and use both channels in >differential mode. I don't think the common mode would accommodate the AC voltage there and still show you the differential. That, and the capacitance from the scopes ground to the powerline with the 3rd pin disabled is considerable. Far more input noise filtration exists in that old Tek than even my Hitachi v1065 would have. With the third pin off, that scope can generate a darned good spark between its case and a grounded item, and if you get between a water pipe and that puppy, you will likely remember it for a while, and you sure don't want to inject that energy into a semiconductor circuit. It would have a 100% tendency to let the smoke out. Then it doesn't work anymore. It might be possible to use one of the new battery powered lcd display scopes for that though. I have been considering obtaining one, but my ability to make it pay for itself at my age and health would make it a certain net loss. I am now 75, and have been diabetic for the last decade. So my warranty has long since expired. :-) >I have also used them on a rubber mat with the 3rd >power wire isolated and scope grounded to the target machine. I have >also been known to blow the internal ground connection of the scope when >I had both the 3rd wire connected and then grounded the scope to the >other device. Experience has a way of providing very graphic examples >of what not to do. Yes, I have found its an excellent teacher myself. But I can beat that, I once slide some big insulating tubing over the probe cable and hung it across the screen supply for a 4cx5000 in a tv transmitter, closed the door on the cable, turned the transmitter on and measured the screen current flowing during the synch pulse. Regardless of how I tuned it, it was drawing over 300 mills during the synch pulse, more than bulletproof evidence that tube was shot. It is a 'shadow grid' tube, and should not have been pulling more than 25 ma at synch tip, 2 ma at normal video powers. I think that supply was sitting at about 1750 volts dc. :) Phillips scopes were truly double insulated via a switch mode supply, and the power cord never had a 3rd pin. > What I need to do is measure the maximum voltage that would exist >between pins 1 and 3 of the PMDX-106 or in my case VFD ground and VFD >+10 lines of the G540. It has two outputs ready to drive relay coils >sinking up to 1 amp from not over a 50 volt source. This should be >sufficient to switch direction and power. The only need I anticipate >for reversing spindle direction is for rigid tapping, I guess I need to >study how that works in EMC2. That will need the encoder on the spindle, but you already knew that so I'll shaddup for now. I started this msg several hours ago, and life got in the way. Sorry. -- 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) The NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> Q: Why is it that Mexico isn't sending anyone to the '84 summer games? A: Anyone in Mexico who can run, swim or jump is already in LA. ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
