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Stepper motor driver 2.3 - what should I check next?

Posted by MotorAssist 
Stepper motor driver 2.3 - what should I check next?
September 24, 2009 12:12PM
Hi,
I have one working stepper motor driver 2.3 (for the Generation 3 electronics), but I can't get one working.
As some of you who have read my blog will know, I killed the driver chip on the first board. For those of you who didn't know, I connected it back to front!

OK, I know, I know.

Now you've stopped laughing, I need some help! I checked the rest of the board, which looked OK, and replaced the chip. I checked continuity between chip legs, and I get the same on the working board as on this one, ie continuity the same, lack of continuity the same on both chips.
BUT when I plug this one in, the power LED doesn't light (I've taken it off, checked direction, which was OK, replaced it) and there is the lightest burning smell. I switched off quickly. Not good.

Now, I have checked all the resistors (all still as rated) except for the 0.25 ohm ones which are below the capability of my meter (read 0.8 ohm on both boards on 200 ohm setting).
The LEDs which indicate the state of the motors all still light up/don't, as they should, when challenged with the diode setting of my meter.

It is possible something else got damaged when the chip blew. How can I check the voltage regulator? Could that be the problem?
What else should I check? Is there anything obvious to you?
Any suggestions (apart from my partner's "bin it and start again!")?

Hazel.
Re: Stepper motor driver 2.3 - what should I check next?
September 24, 2009 02:08PM
Testing the regulator is easy, just connect 12V and see if 5V appears at pin 2.

Connecting the stepper chip the round way round could have damaged it by feeding 12V into its output. There isn't much else you could have damaged so I wouldn't start again.

To measure small resistors with a cheap 2 wire meter you have to subtract the resistance of the leads. Short them firmly together and note the reading. Then measure the resistor and subtract. E.g. my meter has 0.2 ohm resistance in its leads. I would expect to read 0.4 or 0.5.

Edited 1 time(s). Last edit at 09/24/2009 02:18PM by nophead.


[www.hydraraptor.blogspot.com]
Re: Stepper motor driver 2.3 - what should I check next?
September 24, 2009 03:06PM
Hazel

Sorry I don't know where your blog is...

When you say you connected it the wrong way arouund do you mean:-

A. the power to the board.

B. Put the chip into the board the wrong way around.

C. Something else ??

Cheers

aka47


Necessity hopefully becomes the absentee parent of successfully invented children.
Re: Stepper motor driver 2.3 - what should I check next?
September 24, 2009 03:39PM
Hi,
I placed the first driver chip the wrong way around on the board. It blew straight away.

I got a new chip, cut out and desoldered the remaining legs of the old one, and put the new one in the right way round this time.

I've put my blog address below. Have a laugh!


Hazel

[copycatbot.blogspot.com]
Re: Stepper motor driver 2.3 - what should I check next?
September 24, 2009 04:04PM
I presume you don't just mean reconnect the power supply to its Molex connector on the board to test the V regulator?
Looking up how to do it - now done. I'll blog it.

Yep, one blown regulator. Hoorah, it's the first difference I've found between the two boards!

As ever, thank you.

Hazel.
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