Author Topic: -hp- 3478A DMM battery question  (Read 1881 times)

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Offline TimFox

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-hp- 3478A DMM battery question
« on: September 11, 2015, 07:46:37 pm »
I recently obtained an -hp- 3478A digital multimeter and its service manual from separate eBay vendors.  The DMM is in good working order and calibration.
Reading the manual, I found that it uses a 3.0 V battery (BT701) to back up the calibration memory and as part of the turn-on circuitry.  It has an -hp- house number:  1420-0278.  In the schematic, there seems to be no charging circuit for this battery, but the load current should be minimal.  I have not found any information in the manual about the expected lifetime for this battery, or how to replace it.
Does anybody have information or experience on these questions?
 

Offline SkyMaster

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Re: -hp- 3478A DMM battery question
« Reply #1 on: September 11, 2015, 11:09:31 pm »
Does anybody have information or experience on these questions?

Congratulation for your new acquisition.

ModemHead describes in details the steps involve to replace the 3.0V lithium battery, of a HP 3468A, on his website:

http://mrmodemhead.com/blog/hp-3468a-battery-replacement/

 :)
 

Offline radhaz

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Re: -hp- 3478A DMM battery question
« Reply #2 on: September 11, 2015, 11:12:07 pm »
I have performed this battery replacement myself, using a butane soldering iron.
 

Offline bingo600

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