[CoAMarcus]

Angelo,

Everything appears to be correct. The 18,000uF cap will work just fine. It should be fairly simple to assemble once you have all the parts.

Marcus

[sunward]

... The 18,000uF cap will work just fine...

The 20000uF was in stock while others were a long wait delay.

[wes]

The problem that you describe is exactly the problem that I am having with my machine.

I have 960 oz steppers from homeshopcnc that are rated at 7 amps I also have the PMDX 131 breakout board and the PMDX 135 power module and a 800va torroidal transformer.

I am pulling my hair out over this and have been for almost a year now.

Any help at all is needed and appreciated.

[sunward]

...Any help at all is needed and appreciated.

I ended up talking to Wes on the phone for a bit and he is having the same problem I am. It was comforting in a way to know I am not the only person in the world having this problem.

He will be looking into the power supply to make sure it is to spec as per Crevice Reamer's post ( which is very helpful).

As for my unit, I have been busy with other work and designing a new
product so I haven't even looked at it since my last post. I should be taking care of it shortly as I still do need the unit.

If the power supply fix doesn't work, I will just scrap the motors and drivers and go to the local linear motion shop and get parts there.

[Crevice Reamer]

sunward: I just looked at the specs again for your 400 oz motors. They have 1.65 mH phase inductance. The formula for maximum voltage is 32 times the square root of the inductance. The sq root of 1.65 is 1.285. 32 times that is 41 Volts maximum. Your 400 oz. motors should NOT be running at 65 volts.

You could buy Keling's 36V 8.8A power supply for $60 and that should fix you up.

But if you were to wire them as Bipolar Series, (3 Amps and Max voltage of 82 volts.) then your present power supply would be fine. I think either one of these would be a simple solution to your problem.

CR.

[Crevice Reamer]

wes: I don't know what your power supply voltage is, but the 960 Oz motor max voltage is 45 volts. To run two 7 Amp motors you need about 10 amps.

CR.

[wes]

Crevice,

My power supply is a 800va model y236907 from partsexpress.com rated as follows
45+45 VAC
8.89Amps

My 4 steppers are 960 oz rated at 7 amps wired parallel with inductance of 2 +- 20% mH/phase. I am running two on the x axis and that is where I seem to get the majority of my problems.
If I knew how to wire them serially I might try it. Specs serial are: 3.5amps and 8 +- 20% mH/phase.

I read 65.9 VDC coming off of my pmdx 135 power prep module going to the power input on the pmdx 131 break-out-board.

I talked with Angelo from sunward last night and we have the same issues exactly. We don't share the same equipment though. His geckos are 212s mine are 202s. He doesn't have the pmdx stuff that I have.

Another common issue is that the geckos fault when cutting curves. Straight lines seem ok. It almost seems like the sheer number of small moves causes the fault. You can see pictures of my control box at my website. www.doorbot.net

[Crevice Reamer]

Crevice,

My power supply is a 800va model y236907 from partsexpress.com rated as follows
45+45 VAC
8.89Amps

My 4 steppers are 960 oz rated at 7 amps wired parallel with inductance of 2 +- 20% mH/phase. I am running two on the x axis and that is where I seem to get the majority of my problems.
If I knew how to wire them serially I might try it. Specs serial are: 3.5amps and 8 +- 20% mH/phase.

I read 65.9 VDC coming off of my pmdx 135 power prep module going to the power input on the pmdx 131 break-out-board.

I talked with Angelo from sunward last night and we have the same issues exactly. We don't share the same equipment though. His geckos are 212s mine are 202s. He doesn't have the pmdx stuff that I have.

Another common issue is that the geckos fault when cutting curves. Straight lines seem ok. It almost seems like the sheer number of small moves causes the fault. You can see pictures of my control box at my website. www.doorbot.net

So your motors are both over volted AND under Amped? The 8.9 Amps is not enough to run TWO of these steppers let alone four. NO WONDER they fault during curves! To run these properly in Bipolar Parallel, you would need a 45V 19A power supply.

Series wiring would work better for you with that PSU. Your motor supplier should be able to tell you how:

[email protected]

CR.

[sunward]

...You could buy Keling's 36V 8.8A power supply for $60 and that should fix you up...

I looked at those power supplies but they were the regulated ones, so I passed. The unregulated were about the same as what I could build.

...But if you were to wire them as Bipolar Series, (3 Amps and Max voltage of 82 volts.) then your present power supply would be fine. I think either one of these would be a simple solution to your problem.CR.

I looked into changing the wiring on the transformer, but didn't have access to the 4 wires. Only 2 were coming out and I didn't want to go further.

[Crevice Reamer]

I looked at those power supplies but they were the regulated ones, so I passed. The unregulated were about the same as what I could build.

Regulated or not, it would be the easiest fix for your problem and work fine.

I looked into changing the wiring on the transformer, but didn't have access to the 4 wires. Only 2 were coming out and I didn't want to go further.

NO! NO! NO! NOT the POWER SUPPLY wiring--The STEPPER MOTOR wiring.

Change the motor wiring to Bipolar Serial instead of Bipolar Parallel, and your present power supply is PERFECT and needs no alteration. On a lathe, you probably won't notice any change in performance.

http://kelinginc.net/KL34H260-42-8A.pdf

The EASIEST, albeit more expensive, fix would be the $60 36V 8.8A power supply from Keling.

CR.

[wes]

Hello Angelo and Crevice,

Over the course of a year of problems you guys were the ones who helped me find out that my power supply was under-amped. Stan H. is sending me another toroidal transformer that is exactly like the one that I now have. I will add this one to the other one in parallel and will get 17.78 amps and keep the voltage the same.

I talked with Rich at homeshopcnc and he said that my motor will be perfectly fine operating at this voltage. I feel sure that this is the problem since the vast majority of my problems happened on my x axis (2 steppers, 9+ amps together) When I start doing curves, the problem added another 4.6 amps and the geckos saw a stall and faulted.

I will have my additional transformer today and will report the results.

Thanks again.

[Crevice Reamer]

Hello Angelo and Crevice, I will add this one to the other one in parallel and will get 17.78 amps and keep the voltage the same.

I talked with Rich at homeshopcnc and he said that my motor will be perfectly fine operating at this voltage.I will have my additional transformer today and will report the results. Thanks again.

Yes, your motors will run fine with that power supply (WITHOUT any additional transformer) BUT ONLY IF YOU WIRE THE MOTORS IN BIPOLAR SERIES.

With the motors wired Bipolar Parallel, As you say they are, you will be running a 45 Volt max motor at 66 volts. This WILL eventually cook your motors.

If you Don't want to take MY word for it--Call Gecko, with your motor specs, and get a second opinion:

714.832.8874

CR.

[springlakecnc]

wow, a lot of posts about the electrical control system. By chance, did anyone happen to make sure the problem isn't mechanical? lose gibb, no oil on the ways, something's binding? Maybe the accel and decel parameters are set to close to the limit, or rapid traverse is set to high. I liked the idea about the heat sink, i went on many a service call on the old centroid stepper motor controls, the described problem is, it runs fine for about a half hour, then the axis go crazy. The solution was always to fix the burned out fan on the electrical enclosure, EVERY TIME! Good Luck

[wes]

Crevice,

Put the new transformer on today and it made the gecko's fault quicker if anything. The motors that I have are supposed to be fine at the aforementioned voltage but I will try the serial setup since I am getting nowhere with them the way they are now.

I can leave my palm on the steppers while they are running. They never get too hot for me to do that albeit my hands are calloused.

I am also getting a couple of 201s to test with thanks to a very nice person who will remain nameless. Since either one or both of the x axis g202's fault most of the time, I will put them on that axis and air cut a sign that seems to cause the faults. I will find out in about 15 minutes whether or not the problem is the 202's or not.

I did run a 212 alongside my other 3 202's for about 6-8 months without error for what it's worth.

[Crevice Reamer]

So are you saying that the 212 alone ran well for 6-8 months and the others still had problems? If so, it is interesting that a step multiplying drive does well. That makes me wonder what your computer specs are. Maybe you are not getting enough pulses to keep the motors from stalling.

What are your micro step settings?

CR.

[Me2]

Wes,
For what its worth I had a similar problem with the 201's I use, particulary in summer. All three are mounted on a large heat sink and where warm to touch but certainly not hot. One drive would consistantly start to loose torque and then steps. In frustration I had a can of 'cold electrical spray' that I sprayed on the board, the drive came back to life instantly. As it turned out it was the opto chip that was causing the problem. When the drive started playing up one spray on the chip and away it would go. I swaped the chip over onto another drive and the same motor problem would occur, spray again and away it would go. I now have to keep the lid of my box open and a fan blowing over the top. Not good with the dust but it works. I will order a couple of opto's over the net and replace the problem one at some stage.
It's a quick easy test to do and maybe worth it.

Cam

[Crevice Reamer]

Wes: Are you still restricting the drives to only 4 amps?

CR.

[sunward]

...NO! NO! NO! NOT the POWER SUPPLY wiring--The STEPPER MOTOR wiring...

will look into it.

...By chance, did anyone happen to make sure the problem isn't mechanical? ...

It never was mechanical. If I let the system cool down, it would work again. I made sure everything was lubricated where needed. It also failed generally at the same time. Leaving the computer on or letting it cool also had no effect. This happened with 2 computers.

The drives were not at their limits.

... Maybe you are not getting enough pulses to keep the motors from stalling...

According to Gecko drives, the drives stall when there is an overload. The signals are just high and low and would not cause the drives to fail.

.... One drive would consistantly start to loose torque and then steps. ...

This never happened. The drive failed with no loss of steps or holding torque. Just failed.

[wes]

Crevice,

Thanks for taking interest in this topic;

My pc is a Dell 2.4Ghz Celeron with 512 mb of RAM. I am running mach3 and the kernel speed is set at 45000 Hz.

The 212 was in one of the x axis locations (I have two drives for my x). The PMDX 131 board only has places for 4 drives, x,y,z and a so the guy who built the control box called pmdx and asked about daisy chaining the signal over from the x location to the second x. They said it was fine. But, on the chance that it wasn't, I did hook up the 202 in the "a" location and had mach3 recognize it as a slave drive and it still failed.

When I had the 212 on one of the x's my machine quit failing altogether but I never did try anything like a sign during that time period either.

[Crevice Reamer]

Wes: Are you still restricting the drives to only 4 amps?

CR.

What about this?

CR.