[time-nuts] If your 5335A is acting goofy or dead...
orin.eman at gmail.com
Mon Jan 5 15:34:09 EST 2015
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.
On Sat, Dec 27, 2014 at 9:06 PM, Orin Eman <orin.eman at 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.
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