[time-nuts] Temex LPFRS-01 / LPRO rubidium reference repair

Gerd v. Egidy lists at egidy.de
Sun May 26 13:43:30 EDT 2013


I bought a used Temex LPFRS-01 / LPRO from fluke.l on ebay. Unfortunately the 
unit is broken and shows the same defect as was mentioned about a year ago on 
this list: after warm-up it locks for a few seconds, but lock is lost again 
after a few seconds. The lock output pulls low for a few very short intervals 
afterwards, but that's it.

I got a refund (but excl. the VAT I had to pay at customs), so it's just a 
small loss. But of course I want to try to get this thing alive again.

In the post last year it was mentioned that these used units suffered from some 
kind of water damage inside. So I opened up the unit, but it looks clean 
inside. Just very small signs of surface rust on the screws and connector.

Here are some teardown photos I made:

I have connected the serial terminal. When using the "M" command for 
monitoring, the unit returns detailed data. The rb signal level is too low on 
my unit, see the screenshot at the link above.

Was anybody here already able to fix such a unit?

Any ideas what to look for or other insights?

Kind regards,


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