[Coco] Coco 2 64k - heat issue?

[Gene Heskett]

On Sunday 28 June 2015 10:25:47 Robert Hermanek wrote:
> I've always wanted to put a permanent little muffin fan inside the
> case, taking power from somewhere... is there a safe place in a coco3
> to grab a little voltage with clipleads, either 5V or 12V or
> something, and how many mA could the fan be without interfering with
> anything?  Or... so there no easy access, or no surplus power, inside
> a coco?

More years ago than many would think, I did just that, using a fan 
similar to a video cards fan.  I stole the about 9 volts DC off the 
output of the rectifier diode that fed the collector of the 5 volt pass 
transistor. The power transformer seemed able to supply that 50 ma or 
so, and by lowering that collector voltage, it probably cooled that 
transistor by a small amount, 3F maybe.  The fan I rigged as exhaust, in 
the left end of the case, so it sucked most of the hot air off the heat 
sink for the 5 volt pass transistor.  I don't recall the letter of the 
board in that coco2 w/64k (but I still have that coco2 in a box in the 
basement so could check) but I can say that it sat, tucked into a shelf 
that was about 5 rack spaces high, along with a 5" B&W monitor and 2 
disk drives, running 24/7/365.25 (minus power outages of course) for 15 
years.  It also had "The forgotten chip" in it, running os9 level 1 and 
a program I wrote in B09 that imitated a $20,000 EDisk that was much 
easier for the techs to use, and 4x faster.

During which time, total maintenance was 2 failed disk controllers, and 
one drive.  All of which I can in retrospect, lay at the fact that none 
of those 3 items had a 3 pin power cord, so they all were subject to the 
surges of a nearby lightning strike.  Had I switched out the power 
cords, wiring the green wire to chassis and logic grounds, I doubt if 
those failures would have occured.

Thats not too compatible with a 255 foot tower getting its top slowly 
eaten away by lightning, whose grounding was shared with the rest of the 
building and was only 30 feet outside the back door.  That wasn't too 
helpfull for the beacon light on top either, I had probably 8 full sets 
of glassware that pair of 660 watt lamps were surrounded by, blown to 
small bits we could find on the ground during my tenure in that 
title/chair.

I put 3 lightening rods up in the later 80's, with sharp bullet pointed 
tips, around the beacon, and as per FAA regs notified the FAA, but they 
made me take them off as it made it too tall for the distance to the 
airport.  Those rods were up there about 4 months, and the sharp points 
had been burned away, so they were about 3" shorter when they came back 
down.  Those 3 sharp points weren't near enough sharp points to function 
as an LEA Associates static guard.  That takes a roll of barbed wire 
rigged on a framework several feet in diamater around the top of the 
tower, and the points of the barbed wired absorb the static charges in 
the air, making an invisible insulating ball of air that lightning will 
go around, never hitting the tower as it absorbs the charges before they 
can reach ignition voltage.  That was never done because of the wind 
(and potentially ice) loading it would have added to the tower.

Your trivia factoid for the day. ;-)

> On 6/27/2015 11:49 PM, Kandur wrote:
> > Using a DC 5V 2A USB Power Supply Adapter
> > with it, can be had for $2, free shipping.

Cheers, Gene Heskett
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