[volt-nuts] Fluke 887A replacement Null detector with solidstate chopper

[J. L. Trantham]

Robert,

I have one of these meters that is missing the batteries.  Can you tell me
what batteries it uses?  There it BT1, BT2, and BT3 and they all may be
different.

Thanks,

Joe

-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of Robert Atkinson
Sent: Wednesday, August 01, 2012 1:15 PM
To: Discussionofprecisevoltagemeasurement
Subject: [volt-nuts] Fluke 887A replacement Null detector with solidstate
chopper

Hi All,
I recently picked up a 887A AC/DC differential voltmeter. Unfortunatly it
had been dropped, has leaky batteries and is not in great condition. However
on oprning the top cover I noticed that Q106, 107, 108 and 109 were missing
from their sockets. Therse are the monostable and drivers for the 85Hz
chopper. However thay were not inside the unit and the calibration seals
were intact.......
I then noticed that PCB 3 which has the null detector lood shiney ans green.
It appears that the mechanical null detector has been replaced by a new PCB
with a solid state switch. It's marked 887A-4022 P/N812610 (C) 1987 and is
obviously a genuine Fluke item. It has a TO8 IC marked [BB] HL805. Obviously
a Burr Brown chip, But Ican find no info on the chip or the board.
Has anyone any information on this modification?

Robert G8RPI..
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