[volt-nuts] Fluke 845B

[Dick Moore]

On Mar 25, 2010, at 5:00 AM, volt-nuts-request at febo.com wrote:

> Message: 1
> Date: Wed, 24 Mar 2010 21:07:55 -0700 (PDT)
> From: Randy Evans <randallgrayevans at yahoo.com>
> Subject: [volt-nuts] Fluke 845B
> To: volt-nuts at febo.com
> Message-ID: <36415.50427.qm at web37906.mail.mud.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
> 
> I bought a Fluke 845B on e-bay and it seems to work except that it is very noisy on the most sensitive ranges, the drift/noise is up to +/- 10uV and it is very difficult to try and zero it (read impossible).? I would like to repair it but I would appreciate some suggestions on what the problem might be and what I should look for.
> 
> Thanks,
> 
> Randy Evans, AE6YG

Randy, replace ALL the elctrolytics -- a pain but you'll be glad if you really want to use this meter. There could be a problem with insufficent response from the opto-chopper system -- a failing neon bulb or CdS cell could cause erratic action of the chopper. And the first amplifier input stage could be real noisy...

Best,
Dick Moore