Re: Current through the soldering iron tip

Denny Anspach
 

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

 
  

Denny S. Anspach MD
Okoboji, IA



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