Re: Current through the soldering iron tip
Thank you for the heads up. I will test my Weller ( a 51 if memory serves – or fails) tomorrow. If it fails, I will continue to use for general soldering – ie working on turnouts and general wiring, but will have to find a substitute for decoder work.
From: Denny Anspach
Sent: Tuesday, June 11, 2019 11:09 AM
Subject: Re: [w4dccqa] Current through the soldering iron tip
I am the person who alerted Larry to this issue, an issue notably prevalent in non-grounded irons, especially those with ceramic insulation. It becomes a potential lethal problem when soldering fine electronics (read: DCC decoders). An authoritative standard industry text book on electronic soldering strongly warns against using ungrounded irons on such circuitry.
This came to my attention when I sequentially fried the audio circuitry of three new sound decoders, and neither I nor the manufacturer had a clue as to what was happening (although -in frustration- not without some mutual polite finger pointing in the process). A model railroad EE engineer colleague (whose day job is industrial trouble shooting chip problems) -by elimination- discovered the problem: my faithful super-reliable non-grounded red Weller WLC100 soldering station was leaking a measured 28V through the hot iron (the cold iron had no leakage). I banished this iron, and a bunch of other ungrounded irons immediately from all electronic work, switched to a better grounded Weller station specifically qualified for electronic work ("ESD SAFE") and all problems disappeared like the snow in the midday sun.
I have been installing decoders for almost 20 years, so this internal breakdown occurred somewhere along the way, or the decoder circuitry became more vulnerable.
The WLC100 is a very popular work horse model, still very much on the market, and notably has not been sold by Weller as safe for electronics.
Denny S. Anspach MD