[time-nuts] If your 5335A is acting goofy or dead...

Magnus Danielson magnus at rubidium.dyndns.org
Sun Dec 28 11:04:37 EST 2014

We had that issue with the 5335A at work, and replacing the relay did 
the trick.

5335A is still the counter which is easiest to use, even if it doesn't 
have stellar performance, but usually that is not needed.

Where did you find the Service Note?


On 12/28/2014 06:06 AM, Orin Eman 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.
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