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TLE5206 cold solder joint?

I finally assembled my Metal Maslow kit, built my wall-mounted frame, and got ready to calibrate today. I tested the motors/encoders on WebControl before beginning the process, and kept getting a failing left motor result:

Testing L motor:
Direction 1 - Pass
Direction 2- Fail
Testing R motor:
Direction 1 - Pass
Direction 2 - Pass

… and after which, the L motor would spin CCW continuously. I sleuthed around the forums and found a mention of failed left motor tests (Left Motor test fails - #43 by Daniel_Papesca), and a possible cold solder of the driver chip. Sure enough, as suggested by @Jatt, pressing the heat sink of the M3 chip randomly got the CCW spinning to stop. Now the question is: how can we identify the cold solder joint? I snapped a pic of the solder work under my TLE5205 board. I’d like to clean up any other cold joints while I’m at it.

Generally a cold solder joint will have a dull look to it or have a visible ring that looks like a crack in the solder. A 60x jeweler’s loupe comes in handy if you’re trying to spot them, or you could just reflow all of the joints on that chip, one by one.

Thanks for the tip. I can typically catch cold solder joints when there’s a pin protruding past the board (e.g., when a component’s pin leg is sticking out). I’m having trouble here figuring out where the pins are for the motor driver chips!

are they surface mount? what does the other side of the board look like?

Oh, duh. I haven’t soldered any surface mount components before. Should the solder at the ends of the chip legs be checked?

Without surface mount liquid/paste flux, you’re going to have a hard time soldering those, because the solder will try to bridge the gap between the legs. You might be able to reflow with a hot air gun, but it’s 50/50. if you haven’t done it before, you generally dont want to learn on something important. It might be worth contacting @Metalmaslow to see if he’s willing to send you another board, as this one is defective.

Thanks for the tip and all your help so far, @Jatt! I’ll reach out to @metalmaslow. In the meantime, I did try to resolder those legs. It’s not the cleanest, but no legs were bridged (checked with an ohmmeter) and the 3 legs closest to each via are respectively connected. I’m dying to set up my maslow, but I want to be safe and avoid any disasters that might happen due to poor soldering. Is there a way to check that?

As long as they don’t have continuity to each other, they should be fine to test. Don’t put too much of a load on the chip without a heatsink on it.

Yeah, those soldered pins from the chip should be all uniformly attached to the board. That looks hand soldered to me. Does that chip have a large ground pad on the back side also? If so, I’d make sure that one is down properly., But a quick touch up of those pins should fix you up. What board version is that shield?

The chip pins were very uniformly soldered before I tried to resolder them by hand. There is a large ground pad on the back side. I’ll touch that up too, just in case.

There is a “v1.4” stamped on the board, so I’d assume that’s the version number.

sorry you are having issues with the board. we can send you a new TLE5206 board. it will look a little different but function the same. we basically switched to through hole components instead of SMD. please send email since I dont know your address based on your forum user name and also dont’ check this forum every day.

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Thank you @metalmaslow! I just emailed you. I really appreciate your support. Can’t wait to get up and running with your kit!

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