Eggtimer Quasar Soldering Issues

[Orion_FJ]

Hey All, I just finished soldering my eggtimer quasar that I'm going to use in my rockets. I looked at all of the connections and the all looked good so I'm surprised I am having issues.
When I plug in the battery in, the battery leads got super hot and started to burn. I luckily was able to pull it apart pretty quickly. I checked all of the joints again and reflowed all of the resistors. When i plugged a different a known good battery in it did the same thing. I was expecting it this time so it didn't get very hot.

I am hoping someone can look at my work and see if you see something I'm missing.

Part B of this, if I'm able to fix it do you think I'll be able to use this one or should i reach out to them and buy another one?

 

[Voyager1]

A quick look over your images doesn’t reveal anything obvious with the soldering. I will look more closely when time permits. However, given your symptoms of overheating, my initial thoughts are that you might have a short circuit somewhere. This might be due to a faulty component or a solder bridge beneath one of the components.

The first thing I would suggest is to test all of your passive components for short circuits due to solder bridges by using a multimeter initially set to the resistance audible test mode. Before you do this, I would recommend cleaning the board with board cleaner or IPA using an old soft toothbrush. Although the flux residue on your board shouldn’t be conductive, it’s still a good idea to start this process with a clean board.

Apply the multimeter probes to either side of each of the resistors and capacitors to see whether there are shorts, particularly with the components that have a lead connected to the ground circuit, or between the power and ground. Two particular non-passive components of interest might be the rectifier and the voltage regulator ICs.

Also, it’s hard to tell from your images whether your three VN5E160S driver chips are oriented correctly. Check that the beveled side of the chip is on the Pin 1 side pads. I think that they might be the wrong way around. The ST logo should be adjacent to Pin 1 on the IC. If they are the wrong way around then you will have a problem!

Check Cris’s instructions again and contact him to discuss your options.

 

[Lotronex]

Do you have a different set of battery leads you can try?

 

[cerving]

Your driver chips are backwards. From others' mistakes, we've learned that this creates a dead-short. Contact us for replacements... however, it's possible that something else may have been damaged too so we can't guarantee that replacing the drivers will fix it. Remove the drivers and see if everything else appears to work. If it does, then you should be OK just installing new drivers.

 

[Orion_FJ]

Thank you @cerving your response is very helpful. I'll send you and email after I pull those tonight and see what happens.

 

[darrenf]

Thank you @cerving your response is very helpful. I'll send you and email after I pull those tonight and see what happens.

So, did you ever get this resolved?

 

[Rocketholic]

So, did you ever get this resolved?

I'm thinking he ended up getting a new kit or new drivers but that is only speculation. Pulling those drivers off is a real bugger and he may have had to cut the legs destroying them in the process.

I was soldering away yesterday morning before work and swear I had the first driver oriented correctly! After soldering the last pad and then reviewing my work I noticed the chip was backwards. Took some doing but I got it off successfully and re-soldered without any trouble. I'm waiting on my battery leads to show up today to fully power up my work.

Looking at Orion's soldering I think he used a bit too much (MHO). I doubt it matters much for these boards and shouldn't be an issue.
Hopefully it all worked out for him.

 

[Orion_FJ]

Hey Guys, completely forgot to respond. I was able to get new drivers from eggtimer and turn them around. They were simply backwards.

After that everything has been great.

I definitely could have used too much solder, this was really my first attempt at using solder paste and it's a bit of a learning experience. I've used it a few times on different projects at work and I've gotten better at judging how much the pads need.

 

[cerving]

Removing those SOIC-8 chips is easy if you have either 1) A hot air rework tool, or 2) The Chip-Quik SMT desoldering kit. The hot air is a lot cleaner, but the Chip-Quik low-temperature solder/flux does a really good job too... you just need to clean up the mess with desoldering wick afterwards.

 

[Orion_FJ]

Luckily I have a hot air rework tool that made it a piece of cake to pull them off.

 

[Orion_FJ]

Also, @cerving thanks for being awesome to deal with.