[Kenwood] TS-940SAT fan help

[Garey Barrell]

Joe -

What's probably happening to your fan is that the voltage is supplied 
from the 30V supply through a 820 ohm resistor, and your fan draws too 
much current, dropping the voltage too low to start.  If you give it a 
spin by hand it will probably run.   This is a fairly common failure 
mode of the Kenwood fan, the bearings get gummed up and the  _start_ 
current drops the voltage too low to start it.  

So....  You can either change the resistor on the PS board to a lower 
value, or you can do what I did to a 940 when I couldn't find a 
replacement fan for less than $30+ from Kenwood.  If you put a 22V zener 
diode across the resistor, at least 8 volts is supplied to the fan at 
startup.  Once the fan starts, the current drops enough that the voltage 
across the resistor drops below 20V and the zener no longer conducts. 

Whatever you do, you DON'T want the fan to NOT come on.  The internal 
temperature, especially on the PS board, rises enough to damage several 
components and cause catastrophic damage.

The Kenwood fans show up on E* from time to time as the "ship breakers" 
are tearing up working units to sell for parts, since like cars, they 
bring more money as parts.!

73, Garey - K4OAH
Atlanta

Drake 2-B, 4-B & C-Line Service CDs
<www.k4oah.com>



joe barkley wrote:
> I have a very noisey fan on the power supply heat sink.
> I have looked for it and put a couple ads out and no luck finding one.
> I thought I could ad a 2.5 inch 12v dc fan on the back. I founf one 
> and got it hooked up to find
> when the thermal switch kicks in the is 18.3 Vdc. The 12V I have does 
> not like that and will not operate.
> It does fine on 12V. First, does anybody have a fan froma parted out 
> 940 and second
> how can I get that 18 V down to when this fan will go for it.
> Thanks
> Joe
> KI4TZ
>