Need Help! Embeddedtronics UHUServo, works at 24V but not at 48V?

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Thread: Embeddedtronics UHUServo, works at 24V but not at 48V?

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    Default Embeddedtronics UHUServo, works at 24V but not at 48V?

    All,

    I am nearing the completion of my CNC build and am wiring up the servo motors/drivers. I have three embeddedtronics UHU servo boards and the AutomationTechnoloigesInc KL23-130-60 servo motors.

    All seems well with the boards at 24V using a standard switching supply. When I change to a 48V switcher, there is next to no torque (moving the motor by hand causes an error), the UHU chip seems to become corrupt (polling the setpoints shows silly numbers, large negative values for instance). The error led lights instantly. Confusingly, I can run the motors at very slow speeds (<60rpm). Above this they fault.

    I don't seem to have blown anything because hey will happily run on 24V again with lots of torque and speeds up to ~1500rpm (consistent with that voltage level). Attaching the motors directly to the 48V power supply causes them to run at max speed as expected.

    Not sure what is going on but any help would be much appreciated. I *could* run these at 24V but would rather have the option of a bit more speed to be able to gear them down for a bit more torque.

    Andrew

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    Last edited by munchy; 01-26-2014 at 09:30 PM. Reason: fixed links
    munchy, because I eat a lot.


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    I have just purchased 3 boards and 10 chips. I have not started to assemble them yet but I hope I can still find support for these boards. It is not looking good because of no recent posts??? I am still searching..Are you using Mach3 to control them?? Sorry I could not be of any help..

    Brad



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    Hi Brad,

    It looks as though most of the interest (and therefore) support of these boards waned quite some years ago. I thought this would mean that it was a proven design and all of the bugs had been worked out - that doesn't seem to be the case! Having said that - my three embeddedtronics boards worked at 24V, so you may find that you have no problems. I found it quite annoying that the company didn't have an updated BOM, so I had to make an educated guess at some component values.

    I have actually fabricated one of the original UHU boards (a homemade etched board). I've stuffed it, but am having problems communicating with the UHU chip so need to spend time troubleshooting that. I wanted to see if the original board was any better at 48V. More to come!

    To be honest, with the time and money I've spent in components, the Geckos are looking better and better. But I'm an engineer by trade, so I quite like the problem solving and homemade aspect of this hobby. Plus I hate it when something is not working - I need to figure out why!

    Andrew

    munchy, because I eat a lot.


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    Success! I got an original board working, turns out there are a number of things wrong with the schematic/BOM (the serial port is mirrored/LEDs backwards/wrong opto chip on my part). Fixed them all and now I can run my Y axis at 250 ipm using my current servo motor at 48V. That's plenty fast for me so I'll try and salvage what I can from the Embeddedtronics boards onto another homemade original for my X axis.

    Brad - your mileage may vary. I was very careful in my component selection for my original UHU's. Maybe I got one or two components of the wrong type on my Embeddedtronics boards but I don't have the time to go back and troubleshoot their board. Plus the layout is a pain in the posterior to work on.

    Also, to answer your question, yes I am using Mach3 to control them but they take step/dir so I don't think that matters too much.

    Andrew

    munchy, because I eat a lot.


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    Hello Andrew, Uli maybe working on a parts list for version 3.13 I know that doesnt help you though. I bought his boards and they look great. very professional. I ordered my parts through Reichelt Electronics in Germany. After Bank Transfer fee, shipping and exchange rate add $100. I am going to try to use 90 volt 10 amp motors to drive a Heavy duty Gantry Mill. He has great pics in his PDF so if I follow carefully and they send me the right parts I hope to get lucky. Are you using the recommended line amplifiers for the encoders. I am still trying to figure that one out. If you would like to see PDF on 3.13 let me know and I will send that to ya. Good Luck and stay in touch.. Brad



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    I'm just using the layout found in this zip file: http://www.gertronik.de/cncecke/servo.zip. The components I used are taken from the "layout 24_10_05_English" tab of the file 301 Moved Permanently. I purchased my components from Mouser in the US so had to go line by line selecting the right parts. Not sure what you mean by "recommended line amplifiers" - at the moment my encoders are hooked up single ended directly to the UHU board, through the 7414 Schmitt triggers to the UHUcontroller. Seems to work fine.

    I would very much like to see the pdf - I'll PM you with my email address. Thanks! Andrew

    munchy, because I eat a lot.


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    Default Re: Embeddedtronics UHUServo, works at 24V but not at 48V?

    Well, looks like I spoke too soon!!

    The older style UHU Servo boards seemed to work fine. I finished off the machine to a point where I could start cutting material. I was getting a horrible staircase effect on my cuts, and after a program was finished, the machine would not go back to zero. I have spent 2 days measuring and re-measuring with a dial indicator. It seems that the older style boards are losing steps when operated at 48V. I set up a program to move an axis back and forth many times (ruling out backlash). Every time the dial indicator would return to what the machine thought was zero, it would be 0.005" off, then 0.010", accumulating 5 thou per direction change. I tried various fixes to software and hardware, even swapping the motor/encoder. The only fix was to return to 24V. At the lower voltage level, I can run a long program and the machine will always return to zero, dead nuts, to within ~0.0005".

    The only thing I can think of is back EMF that is somehow corrupting the stepping pulses, 5 thou is way more than a single step, so that ruled out the "active high vs. active low" problem that others have encountered.

    So I'm back to running my 60V motors at 24V, meaning my top speed is reduced to ~60ipm. Very disappointing. At least I can cut, but I really would like to use 48V as it would speed up rapids and fine machine work with small bits. I'll keep plugging away but if anyone has any thoughts on what might be wrong please help!

    Andrew

    munchy, because I eat a lot.


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    Default Re: Embeddedtronics UHUServo, works at 24V but not at 48V?

    If you take some time to read the HP-UHU thread (and the original UHU thread) you will find the answer to those problems you are having. Those problems you are having at > 24Vdc are the reason why the HP-UHU boards were designed a few years ago.
    Note: Don't blame the UHU chips... it is the board's design (schematics and pcb) that is to blame. Maybe they designed the board for 24Vdc use only.

    Regards,

    kreutz



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Embeddedtronics UHUServo, works at 24V but not at 48V?

Embeddedtronics UHUServo, works at 24V but not at 48V?