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

[Orin Eman]

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.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.
>
> Orin.
>
>