Author Topic: EEVblog #1152 - 240V-120V=Magic Smoke  (Read 10330 times)

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Offline floobydust

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Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #75 on: June 03, 2019, 04:55:53 am »
I was a kid, figured it out while soldering a neon lamp in a some old gear.
It flashed every time I toggled the trigger  :o

The solenoid-style transformer has high leakage inductance as well, to make it worse.

I told my mechanic buddy to never use a soldering gun on cars and trucks, it could damage the electronics. It's pretty much the only place you need so much heat to solder.
 
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Offline Dundarave

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Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #76 on: June 03, 2019, 05:15:44 am »
I was a kid, figured it out while soldering a neon lamp in a some old gear.
It flashed every time I toggled the trigger
Thanks.  I can certainly understand how the electromagnetic pulse would flash a nearby neon, and I’m sure I’ve had the same thing happen to me back in the day, but I didn’t understand how a spark could actually be generated at the tip from back EMF, especially when my experience indicated otherwise.

But between the large e-mag pulse, and Ian.M’s explanation, I can see how today’s sensitive chips wouldn’t likely stand a chance.

Not that I was ever likely to use a Weller gun again for my electronics work, lol.
 

Offline mcovington

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Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #77 on: September 21, 2019, 11:00:09 pm »
I discovered that my old Weller EC2000 soldering station likewise had no fuse upstream from the transformer primary, so I opened it up to add one... and found that it had been built with live and neutral interchanged.  The published diagram is correct and what I actually found obviously has them backward.  Neutral was connected to the switch.

So now I have even less confidence in Weller than I did after watching the videos!

(Disclaimer: It is conceivable the swap was done by someone repairing it later.  In any case, I have replaced the power cord.)
 

Offline floobydust

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Re: EEVblog #1152 - 240V-120V=Magic Smoke
« Reply #78 on: September 22, 2019, 03:49:01 am »
your blog adding primary fuse, nice pics  :)

I don't see a primary fuse in the Weller EC2000 manual, only the secondary 2A 24VAC circuit breaker EC212 which is useless. It could only deal with a shorted cable/connector to the handle - but does that even happen? It's there only to meet antique UL (soldering iron) standard UL499.
I'd guess the EC2000 uses the Tyco power transformer that may be UL/CSA Class II rated.
 
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