[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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