4988 Black Edition

Hi,

I had bought a Pololu 4988 black edition and its headers were not soldered. I don't have a lot of experience on soldering (and my soldering iron isn't very effective) so I was waiting to gain some experience on other projects before soldering the headers but yesterday I had a stepper problem so I had to go ahead and solder them. Of course, it was difficult for me. Sometimes 2 adjacent pins got soldered together, which I separated with the soldering iron. In the end, all of the pins were in place, there were no visible shorts. When I put the stepper in place, it worked nicely for a few seconds. Then I started to hear a periodic sound from the stepper motors, even when they weren't moving. When I tried to move them, they moved intermittently, pausing every half second. I touched the stepper driver and it was so hot that I couldn't touch it more than half a second. The heatsink was also moving when I touched it and I was surprised to see that a SMD component was attached to the heatsink. I think that the stepper driver got so hot that it desoldered a component. Naturally I had to replace it.

My question is, what did I do wrong? Could this behavior be caused by a short (that I can't see). Is it possible that I've fried a component while I was soldering?

Thanks

You may have caused a short when you soldered it, or the current adjust pot may have been set too high and you just cooked it due to abnormal operation. Those little modules are a poor design that does not provide adequate heatsinking for the driver chips so this is going to be an ongoing problem as long as you use the modules. Get some spares and keep them handy. You'll be cooking a few of them before you get the printer dialed in. Next time, set the pot at about mid rotation before you plug it into the board. Make sure the power is off whenever you plug/unplug the modules or motors.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I used a multimeter to check for the voltage and it was an acceptable value (0,7 I think) so I don't think it was a pot problem. I suppose I shorted something or burned a component while I was trying to solder it.

Possible cold solder? Basically, if the solder is done badly, it will crack and weaken and only work intermittently. You can fix this by reheating the solder on any suspect areas so it flows into the joint. It's highly possible that you fried something though. It doesn't take much heat to start doing damage sometimes. The key is to work quickly and efficiently when soldering I find.

I suggest picking up a cheap DIY kit and practice soldering. I picked up an LED cube from a maplins store (UK), which is great to practice on as too much heat will blow the LED, but they're cheap enough that you don't have to worry about fudging it and you can buy a few cheap replacement LEDs to fix it. Also, you get a cool desk lamp.

ebay DIY kit for an led cube: [www.ebay.co.uk]

Black ones cool, lets hope you get too the bottom of whats wrong with them, how much where they? is it possible the heatsink sorts some of the surface mounted stuff, hopefully the sticky base insulates a little but placing so sides dont touch is tricky,

Best investment I ever made was a good quality soldering station with digital temperature control and interchangeable tips.

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JamesK
Best investment I ever made was a good quality soldering station with digital temperature control and interchangeable tips.

Any particular brands?

I got a GQ Electronics 5200 with hot air rework for about $60 a few years ago. That model seems to have become ridiculously expensive now, but there are similar looking stations at more reasonable prices.

How can that thing cost 1200 Canadian dollars??? The inflation in Canada should be worse than I've thought

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drmaestro
How can that thing cost 1200 Canadian dollars??? The inflation in Canada should be worse than I've thought

Makes no sense to me, I can't imagine they sell any at that price. The 852 seems to be the current equivalent at a more sensible price: [www.ebay.ca]