[time-nuts] Tbolt Temp Sensor

[brent evers]

Spent the day getting two Tbolts I got off flea-bay up and running.
Fun!  Got to know my way around Lady Heather and learned a few more
things about time/freq sources.

One of these units appears to have an onboard temp sensor that is dead
- the temp just reads -55.0C all the time.  This is the little
Maxim/DallasDS1620 chip, which I can replace, but I had a few
questions first.

1.  I'm presuming that this isn't used for any of the oven temp
control loop, and that its OK to run the unit as is.  I can't imagine
it would be and the DAC control voltage for the OCXO is not in runaway
for a hot oven.

2.  Anyone had this fail on a unit before?  Seems kinda odd, as these
little things are in everything and are ususally pretty robust.

3.  I hooked up a logic analyzer to it, and there's data going back
and forth between it and the microcontroller, which surprised me, as I
thought it would be totally dead (but maybe this is just the
microcontroller polling it to send back data?).  I can't make sense of
the data that I see.  Just for my knowledge - Dallas 3 wire is more or
less SPI right?  I think there are a few differences for this chip - 9
bit word, trailing edge clock, and active high on the reset line.
Anyone else ever looked at the data exchange with this device?
Anything else I should know?  I'm just trying to verify that it is
indeed the DS1620 and not something else.

Brent