"Fan for Surecom EP-808SX" Modification
I bought myself an 8 port 10/100 full duplex network switch, which i had been using for 11 months, when it started working intermittently. after opening the unit to investigate, i found evidence that the chip had overheated (shown by the brown burn marks on the pdb).
the unit was installed in a warm enviromnent, so i thought if i was to get another, something should be done to prevent this happening again.
instalation of the fan was simple enough, after figuring out where the fan was to be positioned, a hole was cut with a 38mm hole saw, and four screw holes drilled to mount the fan, using 1" by 1/8" nuts and bolts.
a piece of light plastic was cut and folded to be mounted on the inside of the unit, to direct the airflow along the chip, and towards the power end of the PCB, then out holes drilled in the end of the unit.
power for the 12v fan was drawn from the 7.5v power supply (which measures 10v using a voltmeter) using an adaptor made for the job. although this is not the normal supply for the fan, it is enough for it to run, althought it will not run at full speed.
two things that could be done to improve the design, use a 12v power supply, and either rely on the switches internal power regulator to reduce this for use in the switch (assuming the switch does have a power regulator built in), or use a single chip regulator to reduce the voltage before entering the switch.
secondly, a gard could pe installed on top of the fan, to stop fingers (or other objects) hitting the fan blades.