[volt-nuts] Fluke 731B parts xref

Randy D. Hunt randy_hunt960 at yahoo.com
Thu Nov 22 18:26:10 UTC 2012

On 11/22/2012 7:49 AM, Steve Smith wrote:
> Regarding the 731B:
> The E505 is a 1ma current regulator. It is still available at a 
> premium price but can be replaced by a Vishay J505. Slightly different 
> package, TO92 vs TO18, but it does work. The J505 is available from 
> multiple sources for about US$2 including several on the Bay.
> The U1 LM308 opamp can occasionally be destroyed if voltage is 
> back-fed into the 10V output. Don't ask.
> Regarding the 750A batteries:
> I replaced mine with four ER14250/LS14250 1/2AA 3.6V 1200mAh lithium 
> cells. Remove the original mercury battery holder and replace it with 
> a dual AA cell holder. Use the kind that has the batteries 
> side-by-side because you need to connect to the center tap between the 
> cells. Wiring is pretty much identical to the way the mercury battery 
> holder was wired. Install the lithium cells in a series string and you 
> have +/-7.2V which is a bit higher than the +/- 6.75V of the mercury 
> batteries but still works. The lithium cells have slightly more mAh 
> capacity than the mercury cells and a much longer shelf life which 
> works well for the 750A as the protection circuit draws very little 
> current. Don't disable this protection circuit, it's too easy to fry 
> the divider string if you're not paying attention.
> Thanks - Steve
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You can always contact Fluke as they still stock a large selection of 
parts for their equipment.  Prices aren't too bad either.  I had a 6071a 
generator that I needed some special parts for and were able to get them 
from Fluke.

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