[Coco] Re: 512k CoCo 3 with 6309 on ebay (Mike Pepe)

Rogelio Perea os9dude at hotmail.com
Wed Jun 15 18:45:42 EDT 2005

> Dave wrote:
>> Nice machine Mike!
>> Where did you pickup the 5V off the board for the fan and any current
>> limitation?
>> Cheers Dave
> Right off the main power transistor. The power consumption is really
> quite low, though I usually like to run 12v fans off the unregulated DC.
> Only annoying thing about that is the busier the computer is, the more
> that unregulated supply sags, and the fan's speed drops. I guess its
> like an audio cpu load meter.

Ok, so I was not hearing things :-)

I hooked up a small 12 vdc fan also to the unregulated side of the power 
supply to try and avoid as much as possible overloading the already taxed 
regulated side of the CoCo 3 ps. My fan is set with a bead of hot glue as an 
intake over the vents that are located in the bottom shell of the CoCo case, 
the fan pulls air from below the CoCo and blows it into the metal  backplate 
of the keyboard, as this plate is slanted, it actually helps spread around 
the just dragged in cooler air over almost all the chips in the board. 
Depending on what I was doing while using the CoCo the pitch noise of the 
fan would definetively change, and I figured the pitch change was a result 
of a speed change due to a fluctuaing unreg 12Vdc as the load from the CoCo 
electronics shifted.

While my current internal fan does cool off pretty well the CoCo, it is very 
noisy and currently I am in the process of setting up a new fan in there, 
got me a couple of Minebea NMB 1404KL 1" fans that are quieter. One thing I 
am doing is setting up an external power supply for the fan, I don't want to 
hang it off the CoCo's power anylonger.

-=[ Rogelio ]=- 

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