[volt-nuts] Fluke 343A

Dick richiem5683 at gmail.com
Fri Nov 16 00:56:48 UTC 2012

Hi nuts, thanks for your help with the Fluke 343A. Replacing the p-MOSFET and two 5uF/15V caps, C37 and C42, fixed it up just fine. I checked D and ESR on the other caps in the chopper circuit, and they were good. I've cal'd it with my HP 3458A,and it's working very well.

Now I have a second 343A to bring back from the dead. Some previous tech had replaced most of the 7387 lamps with LEDs, and didn't do a very good job. Trouble is, I can't find a schematic for the LED mod to the 343 -- the one I just fixed has them, but I'd like to know some recommended resistor values for current limiting the LEDs. Some are fairly obvious, but I'd like to be able to confirm values. If anyone has a circuit diagram for the later 343s that have LEDs, I'd be happy to pay for copying or whatever.

 Dick Moore

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