Update. I replaced the relay socket anyway with a 27E213 from Digi-Key. It fits perfectly. The socket I removed was a 27E129. It would seem that the 27E129 should have a ground strap. The one I removed doesn't. Otherwise, the 27E213 should be identical. The Digi-Key part number is PB806-ND.
Although the bad contact with the socket caused enough heat to discolor the base of the relay, I don't think the relay was harmed. I also did the extra wiring from the service note to add a second set of contacts in parallel for the 5V supply. Hopefully this problem is fixed for the next decade or two. Orin. On Sat, Dec 27, 2014 at 9:06 PM, Orin Eman <orin.e...@gmail.com> wrote: > While evaluating my LTE Lite and testing my buffer board, my 5335A started > acting goofy - random hangs/crashes etc.. > > This morning, the fan came on, but no display. > > To make a long story short, the problem was exactly as described in > Service Note 5335A-26B. I found evidence of overheating on the power > supply relay. The 5V (and 3V) supply was down. During investigating the > fault, I disturbed the power supply relay and reseated it. The instrument > worked again. Further investigation revealed a cold looking solder joint > on the relay socket and spread contacts on the relay socket. About 1V was > dropped across the relay socket and the relay itself. I resoldered the > socket and 'persuaded' the contact with a small screwdriver. All now seems > to be back to normal. > > FWIW, do not believe the part number on the relay. It is really a 6PST NO > beastie for which I have not yet found a replacement. > > The above mentioned service note adds a second pair of contacts for the 5V > supply after replacing the 120V fan with a 24V fan fed from the power > switch. This uses the relay contacts that used to be used to drive the > 120V fan. Ideally, you replace the relay and its socket as well, but good > luck finding the relay. My unit has the 24V fan, but I have yet to do the > rewiring for the second pair of contacts, so I suspect the fix might not > last. Still, it's 22 years since the date on the service note, so I might > have a few years. > > So, if your 5335A fan comes on, but no display, check the 5V supply first > and if it's down, suspect the power supply relay/socket. > > Orin. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.