Re: Current through the soldering iron tip

Denny Anspach <danspachmd@...>

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
Okoboji, IA

Join to automatically receive all group messages.