A4983 stepper Motor Driver with Vreg and Motor stepper 1208

I have bought a A4983 Stepper Motor Driver Carrier with Voltage Regulators and a motor stepper (Polulu item : 1208) and I think I have a problem with the card.
I use voltage adapter(220 VAC - 0.35A to 10,6 VDC - 1.32A) as supply for the board and I use a PIC18F4550 to control the step and the direction. I have shunt the 5VDC output and the VDD as you can see in a the attach file.
When I power the board, two components become very hot (see attached file) and the motor don’t move. I have control the VDD voltage of the shunt and there is only around 3V instead of 5V. I don’t know what I can do to understand from where the problem comes.
Thank you for advance to help me to resolve my problem.
Cablage carte.pdf (213 KB)


Since the capacitor is getting hot, I am skeptical about your power supply being adequate. What does your meter show you on the input, and how does that change when you connect the board and disconnect it?

- Jan

I have change my power supply and I now use a Laboratory DC Power Supply (Réf : ISO-TECH IPS-2303).
When the PIC is not connect to the board, I measure the output voltage of the PIC18F4550, I have 5V for the pin that drive DIR and I have 0 or 5V for the pin drives STEP.
When the PIC is connect to the board and the power supply of the board is off, I measure 1.3V for DIR pin and 0 or 2.6V for the STEP pin.
When the PIC is connect to the board and the power supply of the board is on, I measure 2.7V for DIR pin and 0 or 2.6V for the STEP pin.
I have measure the output current of power supply when the PIC is connect to the board and it is 0.33A.
I have verified the resistance of stepper motor coil and I find 19 ohms.

Could you what kind of test can I do ?


It’s not that helpful for you to tell me results of the combination of PIC and motor driver board when I don’t know what your PIC setup is. You should find out if the motor driver is fine first, and only move on to the combination of the two if the individual parts work. If the individual parts work and the combination doesn’t, you’ll have to provide much more information about what the interconnections are.

- Jan

Excuse me but I am french and I hadn’t really understood what you would like I make.

So, when my power supply isn’t connect to the board, there is 10,6V (0A). Then when I connect the power supply to the board (without motor, PIC and shunt), the voltage supply is always 10.6V (0A) and the two component don’t become hot.
After I have just connected the shunt between 5V output and VDD pins, the supply voltage still 10.6V (0.33A) and the components become hot and particularly the one on the right corner of the board.
I hope that will help you to find the problem.

That part is the voltage regulator, and it getting hot (and the current going up) when you connect the 5V line is indicative of something like a short from VDD to ground. Can you confirm that with your meter, and if it’s there, try to locate it?

- Jan

Thank you for your reply.
When I measure the resistance between the GND and the VDD pin there is 100 kohms and I think it isn’t good.
I don’t know how to locate the problem without electrical scheme of board ?
Could you help me please?

100k is quite a bit and would not at all account for the current you’re seeing. The schematic of the board is right on the product page (at the bottom of the main page and also in the pictures list).

- Jan


I have made some measure with ohmmeter to find the problem and this the results in ohms :
VMOT-GND : 200k
DIR-GND : infinite DIR-VDD : infinite
STEP-GND : infinite STEP-VDD : Infinite
RESET-GND : 200k RESET-VDD : 100k
MS3-GND : 110k MS3-VDD : 210k
MS2-GND : 110k MS2-VDD : 210k
MS1-GND : 100k MS1-VDD : 200k
REF-GND : 2.85k REF-VDD : 100k REF-3.3V : 22.5k
3.3V-GND : 23.4k 3.3V-VDD : 125k
5V-GND : infinite 5V-VDD : infinite
VDD-GND : 100k

I think the problem is with the SLEEP pin because of the low resistance with GND.
Could you confirm that ?
From where come from this problem?

Could someone help to solve my problem?
I have look after short circuit between the SLEEP pin and GND but I have found nothing.

Is it a manufacturer problem?

Sorry I didn’t get back to you sooner. It does sound like there is a problem with the chip since the sleep pin should not be grounded. If you don’t see any shorts anywhere (e.g. a blob of solder), I don’t think it’s something that you can fix. You can contact us directly with your order number, and we can at least get you a discount on a replacement.

- Jan

Jan, thank you for your reply.
I don’t know if it is to you I have to take my orber number but it is the web order #73857.
If this number is not for you, could send me the email of the conatct ?

You can use the general email address from our contact page.

- Jan