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

Hello, I cannot help with the original schematic, but I replaced the lamps of my unit with leds. I didnt know that there are units wiht leds from from the manufacturer, I'd like to know more about this also. What is the problem you found with the conversion of your unit? There can be problems with this conversion? I replaced the lamps with high efficiency orange leds, with 1W 2k7 resistor in series, so to have about 10mA of current, the resistors will dissipate around 230mW. Mechanically they fit nicely with the help of a little heat shrink tubing. Here are 3 pics: http://www.flickr.com/photos/14336723@N08/8190772946/ http://www.flickr.com/photos/14336723@N08/8189690069/ http://www.flickr.com/photos/14336723@N08/8189689929/ Fabio. Dick <richiem5683@gmail.com> ha scritto: > 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 > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.