BT139-600G Triac Equivalent

Peter Coghlan cctalk at
Sun Dec 17 07:24:54 CST 2017

> I have a suspicion that this component may be faulty on the input side of my
> H7826 PSU. A little tester I have does not recognise it, it is possible that
> the currents it uses are too low for this particular triac, but I am not
> sure.

What is the function of this triac in your power supply?

I have come across a triac which is used to switch between 115V and 230V input
in the PSU of a DEC 3000/300.  My triac went short circuit which caused some
release of magic smoke when the PSU was used on 230V.  I also had difficulty
finding a replacement for it so I ended up leaving it out.  The PSU worked
fine on 230V only without it once I replaced the other damaged components.  

If your triac has a different function, ignore the above.

Peter Coghlan.

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