[volt-nuts] Fluke 731B battery & charge circuit

Orin Eman orin.eman at gmail.com
Mon Jun 17 02:48:39 EDT 2013

On Sun, Jun 16, 2013 at 11:20 PM, Christopher Brown <cbrown at woods.net>wrote:

> You might want to check/replace the current limiting resistor in the
> batt charge circuit, and the zener.

I'll check the current limiting resistor for sure.  It's a carbon comp, so
it could well have drifted.

> Both of my 731Bs had low zener output.
> Had to replace the zeners in both and that 5ma jfet regulator in one.

The E505 has already been replaced with I presume a J505 as it's in a TO92
case.  Do you remember what your good zener voltage was?  I know they are
spec'd at +/- 5% and the J505 is +/- 20% (don't know about the E505, I
can't find a datasheet) so there could be quite a range.  There is no
indication on the part list that they were selected.  I have some zeners on
order and I'm going to see what I get with 1mA through them.

Thanks for the info.


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