AC Cooling Fans

[julian macassey]

    In response to the continued discussion on cooling the 3b1, here are my 
AC fan installation notes.

    Yes putting in an AC fan may raise your noise level, but it will shift 
more air and not use 12V from the PSU when doing it.

    I still have some AC fans available if anyone wants one, see an earlier 
posting on unix-pc.general for exciting details or e-mail me.

yours

-----
                    Putting an AC Fan in the 3B1

        You  will need a  three inch  axial fan  (115V) with at least 
four inches of wire coming off it to do this installation:

Tools required:
        o phillips screwdriver (med. sized. No 2)
        o 1 small flat-blade screwdriver
        o a pair of needlenose pliers
        o wire strippers or a jack knife 

             Fig. 1 3B1 - Front View (keyboard and mouse omitted)
             ------
                        __________________________
                        |+----------------------+|\
                        ||@@@@@@@@@@@@@@@@@@@@@@|| \_
                        ||@@@@@@@@@@@@@@@@@@@@@@||   |
                        ||@@@@@@@@@@@@@@@@@@@@@@|| A |
                        ||@@@@@@@@@@@@@@@@@@@@@@||   |
                        ||@@@@@@@@@@@@@@@@@@@@@@||  _|
                        ||@@@@@@@@@@@@@@@@@@@@@@|| /
                    +---||@@@@@@@@@@@@@@@@@@@@@@||/---------+
                   / == +----+--------------+----+ ==A===  /|
                  / =======  |      A       | /  =======  / |
                 /____A______|______________|/___________/B |
                 |###########|_____________________A_____| /
                / #C                                #C  / /
               /___________________B___________________//
               |______________________________________|/

A is Monitor cover. B is base cover, leave on for fan replacement.

Procedure:

0) Do a full backup of your drive.
1) Make sure you have a cleared off table or desk with 4'x4' of space 
   to put the machine on.  
2) Use /etc/shutdown to halt your machine. (Must be root)
3) Boot the diagnostic floppy, and park the hard disk's heads.
4) Turn the machine off, and unplug the keyboard and  power cables.
5) Turn all your peripherals off. 
6) Place your 3B1 on the edge of your cleared-off table, with the rear of
   the machine projecting over the edge.
7) Remove the peripherals (printer, RS-232 etc)
8) Grab the phillips, and use it to remove the 2 vertical screws in the
   back  of  the  monitor  case.  They  are normally  hidden  by  the 
   peripheral plugs.
9) Hang one side over the edge and remove the two vertical screws there;
   repeat for the other side.
10) Carefully lift the monitor up and towards the front of the machine - you
    may need to use the larger flat-blade screwdriver to pop the front part
    the case (next to the floppy drive) off. Be carefull here.
11) Set the monitor on its side.  You may need to cut a cable tie to get
    sufficient slack.
12) Locate  the  fan cable  and disconnect  the leads.  Pop the  end 
    connected to the PSU into the torroid in the PSU.
13) Lift  out the DC fan and  put to one  side. Using  a paintbrush, 
    compressed air etc, take this opportunity to flush the dust bunnies.
14) Using needlenose pliers remove  the Power spade connectors  from 
    the back of the IEC Power connector and switch assembly.      
15) There should be at least a 4 ins pigtail of power lead on the fan. 
    Strip at least 1/2 in from each wire.
16) Each of the spade lugs  has a little hole in the  middle. Put a 
    stripped wire through each hole and bend over.
17) Push the connectors back on the spade lugs. This should leave no 
    uninsulated wire protruding. Adjust if neccessary.
18) The fan should have an arrow indicating direction of airflow. The 
    arrow should point to the back of the machine. 
19) Seat the fan in the cavity  and  take care that the  Hard  Drive 
    power  cables  are not obstructing  the  fan blades. Adjust  cable if 
    needed. Spin blades by hand to be sure.
20) Reassemble machine in reverse order to above and turn on machine.  
21) Final check. Place your hand over the  fan grill. There should be 
    air moving and it should be blowing  outwards. There should be no 
    funny noises.

                           Job Finished

Thanks and apologies to pschmidt at bbn.com (Peter H. Schmidt) for providing 
the inspiration and drawing for this document.


-- 
Julian Macassey, n6are  julian at bongo    ucla-an!denwa!bongo!julian
n6are at wb6ymh (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495