(ET) 36vdc relays

["Bill Kelly" <billkelly htva net>]

RJ,

Those 36vdc relays from SURPLUS CENTER definitely have a diode across the 
coil.  I purchase two of the relays and decided to bench test them.

Not worried about polarity, I placed 36vdc across the coil and heard a pop 
and observed a puff of smoke coming from the relay.  I removed power and 
performed a continuity check across the coil and found that it was shorted.

I decided to find out what had gone wrong so I removed the plastic cover and 
found a small diode across the coil connections.  I snipped the leads and 
removed the diode (failure mode - short).

I retested the relay and it worked so the blown diode did not ruin the 
relay.

Further inspection of the relay had shown a "plus" sign painted on the 
bottom adjacent to one of the coil terminals.

So, if you leave the diodes in, you must observe polarity with wire 38 (+) 
and wire 13 (-).  I removed the diodes.

Bill Kelly
Owego, NY