On Wednesday 12 December 2007, Emory Smith wrote: >> amplifiers. The scope should have at least 100mhz bandwidth and the >> probes should be precalibrated so that the test square wave on the front >> of the scope is indeed square and flat top and bottom when observed. > >It is & they are. Tek 475 with switchable probes.
Old but very good in its day. How are the input attenuators holding up? I had to trash an otherwise good 465 a few years ago because of attenuators out of spec, by 50% & tek had no parts! Then a 2235 did the same thing, so now it says Hitachi on both of them. Nice, and doesn't need a tech from tek making monthly visits. >> Also, do not use probes without the 10x attenuation enabled as the added >> capacitance of a direct probe may|will also total the amplifiers. > >Ah, glad you reminded me of that. By the time I would have gotten the vert >gain low enough for the trace to be on the screen, <poof!>. Quicker than that! Milliseconds. >> Informational wise for this sort of troubleshooting, scoping the step and >> dir signals *to* the amplifier, and comparing the rise times, steplen >> times and dir setup times to what the amplifiers need will probably be far >> more usefull. A parport that doesn't have adequate drive will be not only >> slow, particularly the pullup times, but may not have the source and sink >> current cajones to satisfy the amplifiers input voltage requirements even >> with arbitrarily long steps. This is not an uncommon problem. > >Excellent! The PC is a mini-desktop. Most of which are a "laptop-in-a-box" >and have wimpy parports. They also run hotter than I'd like. A lot hotter. >I'll put the scope on the inputs of the stepper >controller. For some reason, I expect to see not-so-square pulses. It wouldn't surprise me to see some fairly slow rise & fall times that don't make a solid .4 or less on the down stroke, or more probably, less than 3 volts on the upstroke. I like to see swings of at least 500 mv above or below the so-called TTL levels myself. That's .2 to 3.2 or a hair more. >It also has a PCI parport card being used for switches, LEDs, etc. >It would be easy enough to switch the plugs and transpose parport.0 >and parport.1 throught the hal & ini files. > >I'll replace the PC-controller cable too. It's just a dirty old >generic printer cable. >Probably not even IEEE-1284. Oops. :) Not every wire possibly? >Anyway, I've been playing with parameters in 2.2.1 that weren't available >in 2.0.1 and have made some improvements. Just found the rest of the info on >steplen, stepspace, dirhold & dirsetup that I didn't have. Looks > interesting. I think it will be too when I get around to trying the new stepper setup on mine. > But it's 1045PM, cold and raining so I'll just wait till > tomorrow. I hear that. I overdid it myself this afternoon, single handedly wrestling 3 each very green & wet white ash planks about 2.5"x7" and 6'4" long, making about 12 crossbar clamps out of 5/16 all thread for bolts, and 2x2's across the top and bolting them down against a steel tubing frame I made several years ago to reinforce the sides of a multi-pocket cement block mold I used to make the blocks for a retaining wall with. About 13" wide, three pieces of 1.5" square steel tubing with a ladder of crossbraces of the same size tubing about every 10". And as flat as I could make it at the time. With 1/2" oak padding so the rust doesn't stain the ash, if a bolt breaks it will be a replay of that old off-colored saw about 30 chorus girls killed by flying shrapnel. The ash is pulling the steel, but the steel will never quit pulling back so maybe by mid-may I'll have some nice straight ash to work up come warmer weather. My shop is tiny by woodshop stds so I was working outside. By the time I got it all bolted up, I had about 140 lbs to wrestle back into the shop and walk back to lean it against the back wall. And my 73 year old back is telling me about it and not mincing the descriptive words a bit. Yeah, its a cardinal sin, but I mix sawdust with swarf in my dodderage. But I hope I'm being helpfull Emory. 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) * Knghtbrd notes he has mashed potatoes for brains tonight <Valkyrie> yum, can I have some? <Knghtbrd> um ... * Knghtbrd hides from Valkyrie ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
