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Topic: Blue Smoke escaping - need clarity (Read 196 times) previous topic - next topic

ribbonman

The blue smoke has leaked out of my cheap stepper driver and I'm trying to pinpoint why it has done that.

I was playing with a new stepper motor(425oz 4.2A) to see what kind of speed I could get out of it. I was using a 48V 10A power supply hooked to a DIV268N driver(rated for 48V 5A) and then the stepper and was running along testing different step rates. The driver DIP switches were set at 4.2A and full steps, I was incrementing the steps and had made it to 8000 steps with no problems. I really couldn't tell any difference in the step rates but it was moving and thought I would run it up until it wouldn't turn the motor any more and know where my ceiling was for it. I put the steps to 15000 and was expecting the motor to just vibrate because it doesn't turn that fast(which I've had happen with other motors) but instead the driver had a loud pop and the ensuing blue smoke(glad it was the $20 driver and not the $200 one).

I'm wondering why it popped, the driver was set to 4.2A so it shouldn't have drawn more than that to overload the circuit?

Did the stepper want more amperage to move at the 15000 steps and make the driver pop?

Just trying to learn as I blow things up.


driver specs
stepper spec

Robin2

I wonder if a nominal 5 amp driver is adequate for a 4 amp motor. I would like more headroom - especially with a cheap driver.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MarkT

No way that driver can handle 5A, it looks to be a piece of junk to my eyes.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

ribbonman

@Robin2 & @MarkT,

The driver is junk and that's why I wasn't using it for anything. I wanted to play with motor settings and it was all I had that wasn't being used at the time so I wasn't worried about it breaking.

I was using it for about an hour on and off and it was working fine being set at 4.2A and turning the motor, I was just surprised that it blew up by changing the motor speed in the code, I thought the Amp setting was supposed to keep to much Amperage from running through it.

Robin2

I was just surprised that it blew up by changing the motor speed in the code,
Maybe its time had arrived and it was just coincidence that you changed the motor speed then.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MarkT

@Robin2 & @MarkT,

The driver is junk and that's why I wasn't using it for anything. I wanted to play with motor settings and it was all I had that wasn't being used at the time so I wasn't worried about it breaking.

I was using it for about an hour on and off and it was working fine being set at 4.2A and turning the motor, I was just surprised that it blew up by changing the motor speed in the code, I thought the Amp setting was supposed to keep to much Amperage from running through it.
I strongly suspect its a single chip driver, 2.5A is about the maximum its sensible to expect from even the beefiest such chip.  The problem is on-chip MOSFETs have orders of magnitude more resistance than can
be achieved with a discrete MOSFET design (discrete power MOSFETs are vertical-current-flow, and
are available in sub-milliohm on resistances, where as integrated MOSFETs are horizontal current flow and
200 milliohms or more typically.  At 4A, two driver MOSFETs of 0.2 ohms each have to dissipate over 6W in
total, and its not even clear if the bonding wires for these chips can handle 4A.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

rtek1000

The blue smoke has leaked out of my cheap stepper driver
R.I.P. (blue smoke = soul of IC)

Does your drive have the IC TB6600?

If it is, according to the datasheet, the maximum current is 4.5A, and peak of 5A.

And still, the recommended voltage for the TB6600 is 8Vdc at 42Vdc,

I'm sorry but using 48V is not a good idea.

So it would already be operating at the limit, so it must have burned so soon.

It is recommended to leave a gap, a good practice is to use only 50% to 70% of the capacity, and of course, to promote the correct cooling.

Another problem is the assembly, I bought some equipment in which the ICs were not touching the heatsink, so the chip gets very hot.

Div268n-5a-datasheet

Datasheet: TB6600HG

Please avoid private messages, your question may be someone's answer in the future!

japreja

You are using a driver that is under rated for your motor.  Higher Current motors require a driver with 2 times the current of the motor.  You will have problems with any driver not rated for 20A with your 10A Motor at the voltage you require.  Make sure your driver states "constant current" rating for amps.  Be leary of small module boards as the pcb traces are nowhere near the rated current of the driver IC.  See this calculator to determine the width of the traces you will need so things do not get hot and poof https://www.7pcb.com/trace-width-calculator.php .  If your driver did not have atleast 1/3 inch wide trace with 2oz copper (3/4in. at 1oz.), that may be why you saw the smoke show!

I have 40A motors that require 60A drivers, if I want any type of certification I will need to boost that up to 80A or better.

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