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.