[time-nuts] New NTBW50AA
Arthur Dent
golgarfrincham at yahoo.com
Tue Sep 10 23:15:05 EDT 2013
>"I would say the temp sensor is working, but still why those jumps?"
Ah, that new temp plot looks like the 'normal' staircase steps I was
talking about. The previous plot didn't look right with all the little steps
in between. As I mentioned before, and Bob mentioned, any problem with
the thermometer chip would only affect carryover and that is probably
going to be a rare occurence. The T-bolt used a Dallas Semiconductor DS1620
and Dallas made an 'improvement' that caused this problem in the T-bolts.
Apparently either the T-bolt firmware couldn't understand the LSD of the temp
string or the new revision chip didn't display it and would display the temp
steps as several times worse than the older DS1620 chips.
The cure for the T-bolts was to replace the DS1620 Rev E chip with an older
DS1620 Rev D or Rev C and the plot would look normal. There was never any
indication that this caused any problem in operating the T-bolt but replacing
the DS1620 chip sure made the plot look better. I replaced all those in the
T-bolts I sold because most buyers would freak out if they saw the steps
caused by the Rev E chip.
The NTPB15AA I have was apparently made in April 2003 and your
NTBW50AA was made in November 2004. This problem started showing
up in T-bolts made after mid-2004 so I suspect the NTBW50AA has the
same problem for the same reason (although the first plot you showed
does look flakey as well). If you want to replace the chip it isn't that hard
to do and I've bought the DS1620 Rev C chips on Ebay for cheap.
-Arthur
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