Need Help!- Linistepper troubleshooting

[shadesdude]

So I'm not quite sure what is wrong so I'll list symptoms.
1) Turns fine using the 555 driver however there is no heat at the transistors just the motor.
2) As confusing as it is with just the X axis having power the Y axis locks up and I assume the Z axis would as well if I had it hooked up. (Ground problem?)
3) Connecting it to EMC and jogging, it makes noises that sound exactly like it is ramping up but it's not turning. (I expect this is a problem with my settings but the motor still gets hot.)


My setup
1) For my power supply I have a homemade 35v 2A which is overkill for the motors I am testing on right now but I also tried a 5v 2.5A with the same results. (Motor doesn't get quite as hot but still heats up)
2) My motors are Lin engineering 4218L-04-07 (don't have the data sheet) 1.2 A 6 wire.

I have a scope but no formal training using it. Attached is a pic of my setup so far. Let me know if you need more info.

[James Newton]

A 2 Amp power supply is no where near enough to run even one axis when you are feeding 1.2 amp /per phase/ motors. There are 2 phases, so the motors alone want 2.4 amps. The driver, 5v power supply and so on ALL need power on top of that. To run all three axis, you need a minimum of 3 Amps PER Axis or 9 amps. And that is a bare minimum. Something like 12 Amps would be better.

35 volts is a bit much, I would recommend starting with 12, which is also good because there are quite a few very inexpensive 12 volt power supplies out there. You can get a PC Power supply for $50 or so that will put out 9 Amps on the 12 volt line. See http://www.marcee.org/Articles/PCPowerSupply.htm or like that for information on converting it for standalone use. You can also pick up 2 or 3 old (cheap) low power PC supplies and "stack" the 5 volt rail to get 10 to 15 volts at 20 or more amps. See http://www.antennex.com/preview/archive3/powers.htm or like that.

For my testing, I picked up a 12 volt, 10 Amp power supply designed for running car accessories at home. I got a steal on it and paid $25, but I see them retail for $50 or so. I generally only run 1 Axis at a time, but I have run 2 Axis on it with no apparent heating.

The other nice thing about 12 volt systems is that you can supplement an (unregulated) power supply output with a car battery. If you don't want to buy one, check the back of any Sears for the stack of old batteries and look for one that is at around 12 volts... lots of batteries loose the cranking power needed for a car, but will still hold a charge and put out more amps than you will need. The key there is keeping it in a box that prevents leakage and doesn't accumulate any out-gassing. The power supply keeps the battery charged, between loads and the battery levels out the load when it is more than the power supply can manage.

Hope that helps...

Edit: Err... this should go without saying but: A FUSE between the supply and the wire connecting it on any major power run should ALWAYS be used. Get the right fuse (e.g. 12 volts 10 amps) and make sure you have a few extras so you won't be temped to short it if you blow a fuse while playing. Individual fuses for each axis (e.g. 12 volts, 3 amps each) are also a really good idea. Again, place the fuse as close to the power supply as possible, in this case, at the point where the wires for each axis split out.

[shadesdude]

Thanks for the feedback. I should be able to convert my powersupply to a lower voltage and higher amperage. The power to the boards is separate and each axis has it's own 2.0 amp supply so I thought it would be enough. I'll post back if I need anymore help.

A quick aside is the overkill on the voltage what is causing the heat in the motors?

[wannabeee70]

Are your tip122's insulated from the heat sink?

[shadesdude]

Yup. I'm almost positive there is no shorting but I'll do another once over.

[shadesdude]

Yeah after a few more checks I'm at a complete loss as to why there is heat in my motors. Granted if it's being caused by the fact it's underpowered and not turning that is causing the heat then disregard this.

[James Newton]

Worry about getting the right supply voltage first.