[time-nuts] HP 5372A Fan

[Pete Rawson]

Ed,

From your description of the fan noise, I have one concern.
If the fan speed seems to increase without a good cleaning 
or change in the supply voltage, then it's likely that the airflow
has been decreased, an obvious speed up is not good news.

Pete Rawson

On Mar 9, 2010, at 10:44 PM, Ed Palmer wrote:

> 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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