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First build! + colour changing diode??

aaronnoraa

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Killed a PL520B a couple of months back and it's next to the one in the module as size reference - They're the same package.
How much current was fed to that PL520 that killed it? Pretty much the first time I've heard of one of those actually dying.
 

Immo1282

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How much current was fed to that PL520 that killed it? Pretty much the first time I've heard of one of those actually dying.
What I thought was initially ESD - and then later discovered it to be an intermittently grounded soldering iron tip - I measured 65V AC between the tip and ground with a painful amount of current leaking through.

I've yet to kill a diode from overdriving it - but I've killed one from that dodgy iron, and one other from slipping when pressing it in with an improvised tool and shearing off the pins.
 

paul1598419

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That is a pain lesson to learn. I hate to lose diodes. I've never lost one to ESD or testing, but I did run through a couple of 405nm diodes several years ago. Had to run the current back on those.
 

aaronnoraa

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What I thought was initially ESD - and then later discovered it to be an intermittently grounded soldering iron tip - I measured 65V AC between the tip and ground with a painful amount of current leaking through.
It sounds like one half of the AC wave is shorting to your iron's chassis. Get rid of that iron!
 

Immo1282

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It sounds like one half of the AC wave is shorting to your iron's chassis. Get rid of that iron!
It's a TS100 temperature controlled DC powered soldering iron, with a crappy cheap switch-mode power supply giving it 19.5VDC. There's no grounded tip unless you add a ground wire (which solves the problem when it's not fallen off...) to a screw on the iron's handle.

It's not half of the Mains AC voltage as I live in the UK which has 240V mains. That was my first guess but I reckon now that the switch-mode DC brick I've got for it is really badly designed and the isolation within the power supply is inadequate - hence there being a decent amount of AC leakage current when the extra ground-wire for the tip comes loose. I know it's a power supply issue as when I run the iron from a higher quality power supply or directly from a battery it does not show the AC voltage on the tip.

Ideally I'd get a proper mains soldering station - but I haven't the space as my workbench shares duty with a dining table, so I make do with the TS100. It's a fantastic little gadget for doing soldering in odd places. A 4-cell LiPo battery pack hidden in a pocket makes it portable, and I've even used it to work on wiring in my car, powering it directly from the car's 12V socket.
 




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