> Am 13.08.2013 21:38, schrieb Rob Klein: >> Op 13-8-2013 20:16, Joseph Gray schreef: >>> I came across a couple of old Fluke differential voltmeters that >>> need some >>> work. I thought it would be best to use low thermal EMF solder on >>> these. >>> >> I think it would be best *not* to. >> >> As far as I know, Fluke never used any low thermal EMF solder on any >> of its equipment, even >> the very top-of-the-range stuff. I certainly never seen it mentioned >> in any service manual >> for e.g. the 720, 845, 750, 752. >> >> >> Rob. I have encountered only one model of equipment that needed low thermal EMF solder; a Holt model 323 AC Voltage standard. The special Cd/Pb solder was needed for the low level circuitry around the thermocouples. I discovered this in my first encounter with these units. I used regular 63/37 solder for a repair and found wild excursions (tens of millivolts) in the output. A bit of reading in the manual disclosed the necessity of the special solder in the unit. Luckily, there was a small hank of the Cd/Pb solder inside the unit, which fixed the problem. As for HP and Fluke equipment, I have never heard of the need for special solder, even in the most tightly specified standards. I don't know if there would be any adverse effects if the low thermal EMF solder were to be used in those instruments, but unless it's specifically documented to be necessary, I would be reluctant to use it, especially since it's so unobtanium. Cheers, Dave M