8100 Magnetek PSU - does the fan always run?

[lobust]

I bought a used PSU (Magnetek 3390-20-001) from, I believe, an 8100 to replace the dead and unsalvageable PSU from a project Quadra 800 I have.

It all works fine but the fan didn't run at all during my limited testing.

Is the fan load/thermal operated on this PSU, or is mine faulty?

 

[lobust]

I bought another identical psu and the fan runs all the time, so I guess the first one is faulty somehow. I will open it up at some point and check it out.

 

[dramirez]

it runs the fan whenever the system is turned on, right?

 

[LaPorta]

Yes, the 8100 fan normally runs the entire time the system is on.

 

[Becks79]

The PSU fan of the 8100 also functions as case fan, and exhausts hot air from the peltier cooler for the CPU, so it has to run all the time. So if it doesn't run, then it's clearly faulty.

 

[mitchW]

Just my 2 cents.
Those Magnetek units need to be fully recapped in my experience as I had 2 of them that were completely blown, and majority of small caps were reading extremely high ESR / low capacitance. The always on 5V standby power supply also cooks the PCB and some of the capacitors nearby. They used quite unreliable Daewoo capacitors in those units which can be found in some other Magnetek PSUs.

If the fan doesn't run, check if its getting 12V, and if it is, then it is most likely just a bad fan.