On Monday, February 09, 2015 02:59:45 PM Dave Cole wrote: > I had a OEM750 drive sitting on my desk so I opened the case and took a > couple of pictures of the board. > This is a 1997 vintage drive. > > https://www.dropbox.com/s/g90twchelqan52b/2015-02-09%2013.23.13%20%28Me > dium%29.jpg?dl=0 > https://www.dropbox.com/s/5lomvxg2r7liks6/2015-02-09%2013.23.26%20%28M > edium%29.jpg?dl=0 > > You will notice the two big electrolytics. The driver FETs (?) > clipped against the heatsink would be easy to replace.
But because they ARE FET's, they will come, or should, with a fine wire wrapped around the legs to short them out and prevent the static from combing your hair or walking across the floor from blowing them. I have been known to retrieve an FET or 3 from duff computer PSU's, but the first thing I do, even before warming up the iron, is to take a 2" piece of stripped wire wrapping wire and using suture clamps, weave it thru and around its legs to maintain this short while I am wrestling it out of the holes, and it is not removed until such time as it has been translanted to where it goes. Yeah, its a PITA, but neccessary. If you can read transistor specs, old PSU's are a truly marvelous source of repair bugs. When I blew the single one in the HF Micromills controller, I removed it, looked up the specs and came to the conclusion that I was lucky it lasted as long as it did. The first one I checked from a duff supply was 2x the d-s volage rating, and 20x the current rating, at about 3x the gate capacitance. Its been in there, and blown about $50 worth of fuses since in the 6 or 7 years its been there. Gate capacitance in such a situation is important as the bigger rated bugs will have more, and the driver transistors that charge and discharge this capacitance must be big enough, and supplied with large amounts of power supply rail to rail bypassing as close to them as is physically possible because if they are not capable of doing the switch drive transition time in way under a microsecond, then the big bugs are left in a semiconducting state for too long and the heat shock will fail them shorted in a short time. Knowing that, I surveyed the board with the motor running, with an IR thermometer and could not find anything running more than 10F above ambient, so I had hopes of it working until I could get another control. That worry was apparently a waste of time, 6 or 7 years later its still running fine with its heat trapped inside the same box the PMDX-106 controller lives in. I have plans afoot to replace that 200 watt motor with the 400 watter I took out of the lathe, making a nice quiet belt drive out of that nylon geared rattle box that will spin the tool at 4 or 5k revs. If I do it right, the head will actually lose weight because my 1/2" thick alu stock has to be lighter than that huge 12 gauge steel box there now. That oem controller has a very stiff control, I do not hear it slowing a bit as the load builds up to fuse blowing amperage. So I've had an ammeter watching it for several years now. Sure saved a few boxes of fuses too. ;-) > These drives really doesn't throw off much heat when running the big > steppers on my Bridgeport. > > Parker still sells this same drive model. > > Dave > > On 2/9/2015 2:37 PM, Dean Posekany wrote: > > On 2/9/2015 1:46 PM, Kirk Wallace wrote: > >> On 02/09/2015 06:36 AM, Dean Posekany wrote: > >>> Thanks everyone for your insight. Its really been helpful. I > >>> think I'm going to pick up one of the cheap MA860H's, install it > >>> and use the pulled Parker drive for a back-up. That way I can > >>> give it a spin before committing to the other two axes. > >>> > >>> Anyone out there have any proven step and direction timing numbers > >>> or will the Leadshine numbers work fine? I've read some opinions > >>> out there that the cheap Chinese knock-offs are a far cry from the > >>> actual Leadshine drivers. > >>> > >>> Thanks again. > >>> Dean > >> > >> So far I'm using the numbers from the stepper timing data page on > >> the wiki: > >> http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Stepper_Drive_Timing > >> > >> Leadshine USA Analog M860H 80VAC 7.2A 1500 1500 8000 5000 > >> Rising > >> Edge http://leadshineusa.com/UploadFile/Down/MA860Hm.pdf > >> > >> I am also using a parallel port software step generator, and found > >> that playing with these values doesn't do much. I think this is due > >> to the low base frequency available from the parallel port. The > >> step generator reads the entered numbers then uses these to > >> calculate actual numbers to use based on the base frequency, or > >> rather base period. There is usually so little resolution (or the > >> base period is large) that one may select 8000 but the next > >> available value might be 14000. I believe "halcmd show" will show > >> the values used with the relevant pins and parameters. Hardware > >> step generators usually have a much higher base frequency, so > >> choosing 8000 might give an acual value of 8100, so one can tweak > >> the numbers to get a feel for where the limit might be. On my mill, > >> I'm using 1/4 stepping and getting around 80 IPM which is slightly > >> faster that my previous setup so I'm happy. > >> > >> I took the cover off my drive and it looks to be well made. The > >> circuit board is used to clamp the power devices to the heat sink > >> and is fairly bowed, which I don't like much, but that is standard > >> practice these days. The motor power IO connector seems to be prone > >> to burning due a marginal connection between the pins and sockets. > >> A bad connection has resistance, which produces enough heat to burn > >> the connector. > > > > Thanks for all that, Kirk. I'm really looking forward to the > > comparison test between the Parkers and the MA860H. > > > > And I will certainly let everyone here know when the Parkers hit > > Ebay. > > > > Dean > > > > > > --------------------------------------------------------------------- > > --------- Dive into the World of Parallel Programming. The Go > > Parallel Website, sponsored by Intel and developed in partnership > > with Slashdot Media, is your hub for all things parallel software > > development, from weekly thought leadership blogs to news, videos, > > case studies, tutorials and more. Take a look and join the > > conversation now. http://goparallel.sourceforge.net/ > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > --- > This email has been checked for viruses by Avast antivirus software. > http://www.avast.com > > > ----------------------------------------------------------------------- > ------- Dive into the World of Parallel Programming. The Go Parallel > Website, sponsored by Intel and developed in partnership with Slashdot > Media, is your hub for all things parallel software development, from > weekly thought leadership blogs to news, videos, case studies, > tutorials and more. Take a look and join the conversation now. > http://goparallel.sourceforge.net/ > _______________________________________________ > 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> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. 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