Peabody says...
Jeff Liebermann says...

http://www.digikey.com/product-detai...967-ND/1095291

I ordered this one today from Digikey. Came to $5.27 with
shipping. It should be here Saturday or Monday, and I'll do
the switch-out and see what happens.


I guess there's always the possibility that the problem will
turn out to be something else, but the fact that the problem
is intermittent, and that the UPS behaves normally in all
other respects, makes it seem likely that the relay contacts
are responsible. But, you know, it's only $5 either way.

I really appreciate your help with this.

The relay arrived this morning, and I've installed it, and everything
works fine so far. Of course I don't know for sure that the relay was
the problem because it was an intermittent problem to begin with. But
I've gone through about a dozen tests with the new one and it hasn't
failed to work. So I'd say this looks promising.

I have to keep the old relay in case I ever need to send the unit in
under warranty. So I won't be taking it apart. But, it does rattle
when I shake it, which I think is not a good sign.

Anyway, time will tell. Thanks again for your help.

By the way, I assume the lead-free solder they're using now has a
higher melting point than the 60/40 I use - it was a bear to get the
thing unsoldered with my 30W iron. Ended up having to add some of my
solder to the pins, then braid it off, two or three times before it all
wicked up and the holes opened up.

And Digikey is amazing. I ordered late Thursday afternoon, and it
arrived in the mail Saturday morning, all for $2.20 postage. Hard to
beat that.