Re[2]: Poor P/Button Switch Contacts ESP-2

[roseb@SMTP-gw.gdls.com (Boyd H Rose)]

Subject: Re: Poor P/Button Switch Contacts ESP-2
Author:  radsafe@romulus.ehs.uiuc.edu at Internet/Unix
Date:    6/21/97 5:57 AM

>I have a couple of questions that I hope someone out their is willing to 
comment on.
     
>1       Has anyone had trouble with push button contacts on an Eberline ESP-2.
     
>         Contact is made across two printed circuit tracks by a ?? conductive
button about 3 mm       diameter connect to a flexible apron. Cleaning the 
tracks and button surfaces did not seem to      make a permanent difference. It 
is time consuming removing the circuit boards to access the     switch
surfaces so I want to get it right at the next attempt.

        I do not have an ESP-2 but I do have four Eberline SRM-200s, similar to 
the ESP-2, which I have had since 1988.  I have had similar problems with the 
"chiclet" type push buttons since 1988 - problems from double contacts to no 
instrument response to the switches at all.  Sometimes cleaning the contacts and
resetting the units worked.  Most of the time, repair vendors stated that the 
problems were the result of bad microprocessors or pc boards in general.  I have
had to have board replacements on all of the units with two units having two 
board replacements.

        The SRM-200s are used lightly at my facility,generally for laboratory 
counting of beta and gamma contamination wipe samples.  In my opinion, base on 
my past experiences with the instruments, the SRM-200 is not sufficiently 
"hardened" for use in areas where EM spikes occur as a result of arc welding 
(causes the instruments to severely malfunction and have to be reset and 
restandardized each time) or in dusty environments (i.e. where significant 
grinding occurs).

        The SRM-200s are very nice multi-configuration instruments when they are
working properly.  In my experience, however, they spend more time 
malfunctioning than operating correctly.

Boyd H. Rose, CM
Radiation Protection Officer
General Dynamics Land Systems Division
roseb@gdls.com


The opinions expresses above are solely my own and do not under any 
circumstance reflect those of my employer.