My first Driver not working

[ghadden]

I am also new at this. I have been all over this site and think it’s great. Most of the information is over my head. I have looked at PlasmaCam and decided to build one like it after I found a book called “CNC Robotics” by Geoff Williams. I have made the three driver boards using the L297 L298 IC chips and one interface board. I hooked them up to two different motors and all I got was heat. The motors were 1)Inland/Nippon PJ80A1-77 and 2)Rapidsyn 34D-9213B. I can’t find any information on either. I got a Delagrange Technology 4XCNC10B board and tried both motors again this time in unipolar but with the same results. The power supply is a computer p/s and I am using the 12v for the motors. The rapidsyn voltage is 1.65vdc. I am using kcam for software.
The table I have planned will be about 6’x7’.
Do I have the wrong motors? I have three of each.
Has anyone had any experience with this book?
Did I waste the last two months by building my own boards?
Anyone else in Anc. building a plasma table?
Any help would be greatly appreciated. I don’t know which way to turn.
Thank you.
Guy Hadden
Anchorage AK.

[H500]

If you are highly motivated, I can help you troubleshoot. I should warn you that the l297 is non-microstepping, so even when all working as it should, you might end up with a resonance problem that is not easily fixable without a new drive.

What is your level of electronic knowledge? Do you have an oscilloscope?

12V seems awfully low for a chopper drive. Are you sure the board can run at that value? Computer supplies and chopper drives often don't like each other. Measure the voltage ( with the drives attached) and make sure you have 12v. I

When you power up, do the motors lock up?

What current is the board set for? What is the rating on your motor's nameplate?

[ghadden]

My knowledge is rusty-amateur at best. I know alot but can't remember much of it. I do have an oscilloscope. I have 11V. The motors are locked up with power but the l298 got hot quick. I don't have any way to set the current on the board that I know of. The rating on the motor is 1.65VDC & Current 6.8A. I can't find any other specs.
Thank you for helping.
Guy

The more I learn, The less I know.

[pminmo]

Your L298 is only a 2A driver, it won't handle that motor. A circuit should supply a reference voltage to limit max current on pin 15 of the l297. The max current is based on the sense resistor (low ohmage resistor(s) off pin 1 and 15 of the L298.

[H500]

It should be possible to drive the motor with 2 amps. The performance will be less than 1/3 of what it could be, so you will need to decide if it's worth troubleshooting. If your machine is low friction and not too heavy, I think the performance will likely be reasonable with a higher voltage power.

First step is to look at the power supp with your scope. Make sure it's not shutting down intermittently.

[ghadden]

I switched to my smaller motors to keep the heat reasonable. I have hooked it up full winding. The only info on the data tag is 1.68 ohm/phase. The power supply is not shutting down.
I would like to get this running but if I need to buy new motors, drivers or power supply I would like some recommendations.
I'm not sure I understand all I know about power supplies. All I read about voltage was they used 24-36 volts. Dose that have anything to do with the data plate rating? It seems the more volts the more amps with a given motor coil. I=E/R
I missing something somewhere.
Thank you
Guy

[pminmo]

You need to know more than the coil resistance. The dataplate should have the coil max current rating on it.

[ghadden]

It only has Type-PJ80A1-77, OHM/PHASE 1.68,LOT NO 88K, 44A501912-001 It's inland/nippon and seems to be NEMA 23 size. I can't find any web site to get any more info.
Thanks
Guy

[pminmo]

Looks like it might be out of a Genicom printer?

[H500]

If the motor is 2" dia X 2.5" long, it's actually quite small and I doubt that it can handle 6.8 amps you quoted in an earlier post. A more reasonable value is 1.5-2 amps.

A chopper drive like the l297 has circuitry to control the current independent of the power supply voltage. You need to set it properly with current sensing resistors, or you could burn out the motors and drive.

As I mentioned earlier, 12 volt is quite low. Your circuit might not have been designed to work that low. Have you checked the design specs?

[ghadden]

Sorry I’m so confusing; I’ve been trying to get some motion somewhere. I have two different motors I have been trying. The smaller motors look like the Applied Motion with about 2.3V, 2.3A. I am trying to use the l297/l298 drivers with these. The large motors are rapidsyn with 1.65VDC and current 6.8A. These are the the ones I hope to use on my machine. The driver I am using with these is a DTLLC 4XCNC10B, but I need to work on a power supply for that. Shouldn’t the motor turn, even with low voltage?
Hope this clears up some of it.
Thanks,
Guy

[H500]

If the voltage is too low, the L297 chip won't work right.