[volt-nuts] Sn10Pb90

[Dave M]

> 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