[time-nuts] -hp- 10811 repair (Thermistor)

Dan Rae danrae at verizon.net
Thu Jan 22 17:32:15 EST 2009


The 10811-60111 that came in my 5370B counter turned out to have an open 
circuit Thermistor in it.  This is a "non-replaceable" part in theory.

However, nothing to lose, I have successfully substituted a Digikey Part 
number: 317-1371 100 kOhm 1% Thermistor ( from Cantherm, part number: 
MF51B104F3950 ).

I measured the resistance of it at the target oven temperature, working 
back from the selected value of R20 that was installed in mine, in this 
case 0 Ohms for 84C.  In fact this thermistor must be very similar to 
the one used originally, since I only needed to use a value of 110 Ohms 
for R20 to get bridge balance, instead of the short that was in there 
previously. 

Good enough for me...

Dan







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