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Author Topic: Tales from the Workshoppe: Soldering Station Autopsy  (Read 174 times)

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Offline jbkuma

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Tales from the Workshoppe: Soldering Station Autopsy
« on: May 24, 2020, 09:41:01 AM »
I was setting up a live stream to record repairs to my giant pixel matrix board after my dedicated 20A 3.7V supply failed and zapped a few of the pixels when it inexplicably went to 7.4V.  I started warming up the soldering iron and left the room to fetch some tools. I returned to realize the soldering station wasn't on like I thought.  I double checked that it was plugged in, and switched on.  Sure enough, I flipped the switch on and off and.. POP, FIZZ, HISS, GURGLE.. the electrons started leaking everywhere and the magic smoke let loose.

I quickly unplugged everything and took it outside for an autopsy.



Nothing immediately jumped out to me.  There were no burn marks or popped capacitors, the transformer was warm, but looked OK.  I was about to chalk it up to a problem in the windings shorting out when I noticed the cracked and splatted transistor.


It's a TIP122, and it's a fairly common, off the shelf type part. In the before times I might have been able to run out and get a replacement to attempt a repair today, but now I'll have to order it and wait and hope for the best.

It has occurred to me that the power supply that got zapped was plugged into the same outlet.  I have had my laptop, stand mixer, and various other devices plugged in there at different times without issues, but it seems a ghost may be inhabiting that socket.  I'm not sure.  Maybe it hates pixels?

In the meantime, I'm shopping for a replacement.  Even if it's possible to repair the old gal, I need to get some projects done and my backup is not really up to that task.  I have a few orders for PCBs and other goodies that will offset the cost, unfortunately I was hoping to offset my rent with that income since I was laid off just ahead of the shutdown.