[volt-nuts] Looking for Fluke 845AB manual

Dave M dgminala at mediacombb.net
Tue Aug 23 18:27:49 UTC 2011

> Charles:
>    I have a Fluke 845AB original manual P/N 294173 dated November
> 1967.  In comparing the "pdf" file "845A_AB_imeng0000.pdf", which is
> also a scan of P/N 294173, which I downloaded from the Fluke website
> sometime back and I find that this file is missing pages:
> 2-2
> 2-3
> 2-4
> 2-5
> 3-2
> 4-4
> 4-5
> 4-6
> 5-1
> 5-2
>    It also seems to be missing 1/2 of the schematic from the "dark
> blobs", and to the right.
>    However the Fluke file does have a newer "Change/Errata
> Information" sheet than I have.
>    If you still need these pages I can scan them into a "pdf" and
> email them to you.  You will have to do a "cut and paste" on the
> schematic as I can only scan 8 1/2x 11 and the schematic is 8 1/2 x
> 34 inches, or 4 pages across.
>    Let me know.
> Bill

You can purchase a complete high quality PDF of the 845A/AB manual from Dave 
Henderson at http://www.artekmedia.com .  I just purchased a download of the 
manual for $10 US, and can vouch for its quality.   Very clear scans, with 
NO MISSING PAGES.  It's P/N 294173, dated November 1967 copyright 1981.

Along the same thread, as Bill notes, there is a change/errata note in the 
manual on Fluke's website that says:
A major circuit modification has been made to the Fluke Model 845AB. This 
change entails the complete redesign of the Photo Modulator, previously 
based on photo-conductive resistors. The new circuit now employs 
optically-isolated Bilateral Analog FETs, and is fabricated on an additional 
circuit board.
Updates to the relevant sections of this manual are now in process and will 
be available for shipment approximately December 1993. This manual is 
completely accurate with regard to specifications and operating 
instructions. The circuit modifications are totally internal and are 
completely transparent to the user.
If you have any questions regarding repair and/or service of your 845AB 
please contact your nearest Fluke Service Center (see the list attached to 
this change/errata.)

Does anyone have any info on the design changes described in the errata 
note?  The old photo modulator/demodulator design used by Fluke and HP is 
troublesome due to deteriation of the photoresistors and neon bulbs,  I 
surely would like to see a schematic & parts list of the design change. 
I'll bet the new circuit could be used in many of the Fluke differential 
voltmeters, too.

dgminala at mediacombb dot net 

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