Re: IIgs internal fan hookup question...

[Rubywand <rubywand@swbell.net>]

Perry Dueck writes ...
> 
> If one were to install an internal fan in an Apple IIgs, what is the
> proper Amps level that the fan should be rated at, in order to connect it
> to the two pin fan connector at the rear of the IIgs motherboard?
> 
> I pulled a perfectly good working fan out of a non-functioning 386sx power
> supply. This fan I have is an  NMB "FLOW MAX", and it is rated:
> DC +12V   0.14 Amps.  Is this the proper amperage level, or is it too low
> or too high?
> 
> What was Apple's IIgs fan rated at (just for comparison)?
>

     An internal fan is not standard on the IIgs. Most users depend upon 
System Saver GS to handle cooling.

     The fan you rescued from a '386 should run okay in the GS. Whether or 
not it will serve any useful purpose is another matter.

     The GS case is not designed to take advantage of an internal fan. With 
a fan mounted on the power supply, you can, mainly, blow air around inside 
the case. The fan is not much good for drawing in cool air from outside and 
pushing hot air out.

     Perhaps, as Charles Plater seems to suggest, there is some reason for 
an internal fan. Mounted on the power supply (which is the only place a 
mounting point is available), a fan could blow some air into the power 
supply. Supposedly, this could extend power supply life, especially in 
combination with a System Saver GS which would take care of drawing in cool 
air from outside.

     The traditional problem with internal fans in the GS is noise. This, 
along with the fact that

1. in any case, you will want a System Saver GS or some similar means to 
provide genuine GS cooling

2. the DC fan draws power from the power supply 

3. the fan connector uses the +12V pins which are, also, used by a popular 
sound digitizer card

4. the fan may generate electrical noise which degrades quality of sound 
output

5. the fan may prevent plugging long circuit boards into some Slots

6. many users have 11 year-old GS's with original power supplies which 
continue to work fine with no internal fan ...

explains why internal fans have not been popular in the GS.


     If you want to use an internal fan, go for a thin, low-current, 
ball-bearing model. If you do not mind opening the power supply case and 
soldering to the switched side of the AC line, a 117V AC model could be 
installed. This would circumvent a number of problems associated with a 12V 
fan.

     Since you are just going to move some air into the power supply, a 
low-airflow fan is fine. Noise will be much reduced vis-a-vis a high-airflow 
model.   


Rubywand