[time-nuts] HP 5372A Fan

Ed Palmer ed_palmer at sasktel.net
Wed Mar 10 05:44:03 UTC 2010


I have a question for owners of the HP 5372A (and probably 5371A) Time 
Interval Analyzer.

Is the fan on the back blowing out or sucking in?

I was looking at mine to see about replacing the fan with a quieter one 
and I was surprised to see that mine is sucking in.  This doesn't make 
sense to me for two reasons:
1.  It blows hot air out the front and bottom straight at the operator.  
Uncomfortable on a hot day.
2.  Just inside the unit at the back on the motherboard there's a 
temperature sensor that controls the fan speed.  Why would you blow cool 
outside air over the temperature sensor?

It would seem to make more sense to have the fan blowing hot air out the 
back and drawing the hot inside air over the temperature sensor.  I 
experimented with this configuration and found that the noise level went 
up because the fan was turning faster - no big surprise there.

I can't find any info in the manual (service or operating) about this.

Ed







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