Re:Solution to ARX/AMX preamp problems

Jane Strouse (mjs@argon.chem.ucla.edu)
Fri, 31 Mar 95 09:15:03 PST

>During the last 1.5 years our proton preamp on the AMX-300 has broken
>down at least 10 times, as we remember. This seems to happen between
>experiments, and not during them. In 10-15 % of the cases the signal
>level is down by a factor of 256/16 or so, and in the rest of the cases
>it is completely dead, and one cannot even wobble - RG increments
>up to 4096.
>
>A repaired preamp and a modified transmitter (that would not 'ring')
>were installed this afternoon - worked fine for a few hours, and
>then the same story again ...
>
>The thing is getting annoying, although the instrument is still
>under warranty, and we get a new preamp in a few days ....
>
>Has anyone of the BUM subscribers had any similar experience, or
>knows a possible cure for this problem ??
>
>Peter Stilbs
>

Dear Peter,

I had exactly the same problem on an ARX400 with the new style preamp.
We replaced the proton preamp about 5 or 6 times. The last time we also
replaced the control box on the top of the preamp housing and the problem
has not occurred for more than a year. I have just returned from ENC where
I encountered several people who have been through the same scenario.
Clearly not all instruments suffer from this problem since I had two
virtually identical instruments installed at the same time and the problem
never occurred on the other one. I am sure that someone at Bruker must have
some idea about the source of the problem and a more permanent fix for those
who still have it happening. I am sure that Bruker users would appreciate
very much hearing from a knowledgable person at Bruker about this problem.

Jane Strouse
mjs@argon.chem.ucla.edu