[Coco] CoCo 3 Voltage Regulator heat sink

[Stephen Adolph]

I'm sure everyone knows this, but the +5 supply in the COCO3 looks to
be a linear regulator..no wonder it is so hot.

I'm thinking about a 512k upgrade, but this power issue is pushing me
towards my "sram version" as opposed to a "dram version".

Also, a good argument for the 63C09 (or B).

I wonder if there is a nice little switchmode supply, like a PC VRM,
that could be dropped in there.  I don't know of any "common" VRMs for
5V (something I could find in my scrap electronics pile for example).

Anyone know of a nice tidy solution, that can work as an upgrade to
the standard COCO3?

..Steve


On Thu, Apr 9, 2009 at 9:14 AM, Gene Heskett <gene.heskett at verizon.net> wrote:
> On Thursday 09 April 2009, Rick Taylor wrote:
>>I had found a heat sink in a box - it's something I pulled out of an old
>>switching power supply, I think, maybe 3.5 inches square aluminum with fins.
>>I have it vertically mounted, seems to be adequate, but barely.
>>Incidentally, while putting the thing vertical, I applied a bit too much
>>torque and crunched the D880. I went to Jameco (with the mobo) and picked up
>>these at their will call counter, with a little help from them figuring out
>>what to use
>>
>><
>>http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&sto
>>reId=10001&catalogId=10001&productId=33048&
>>
>>
>>I'm running it off a 200W AT style power supply. It's getting fairly toasty
>>but it's been running for about an hour and nothing's caught on fire yet
>>
>>:-)
>>
>>You can hold on to it for about three seconds before you go "wow! that's
>>hot!" and let go. I'm not particularly good with electronics. What would be
>>a better replacement that might run cooler?
>>
>
> If you have the schematics, its not too hard to just toss the heat sink &
> transistor, and hook the AT supply up to it directly.  I did that about 15
> years ago for both the mpi and the coco3.  Without that coffee warmer, and
> with a disto 2 meg ram kit + a 63C09 in the cpu socket, the half a watt the
> gime warms up is about the sum total of the heat generated in mine.  With a
> furniture blanket on top of it hiding a darkroom thermometer laying on the
> grill above the memory, it will read 2F above the room after 24H of uptime.
>
> I used one of those auto part stores 4 wire connectors that I just replaced
> yesterday because it was getting noisy.  Now I have a nice clean screen again.
>
> I also have an error 246 when I try to use the /p port since then, so I may
> need to recheck my work.  The wires in the kit I used are heavier than the old
> one had, and I was forced to leave off the ssnapon rf chock I'd used
> originally and re-arrange the connections & maybe didn't get the + & 12 volts
> connected correctly again.  The rest of the coco3 wouldn't care.
>
>
>>On Sat, Apr 4, 2009 at 5:06 PM, Robert Gault
>>
>><robert.gault at worldnet.att.net>wrote:
>>> N8WQ wrote:
>>>> Well I have my new 40 pin pcb connector soldered on the motherboard at a
>>>> 90 degree angle and it is working great in saving me some space in my
>>>> mini tower case. My next project is to put the stupid voltage regulator
>>>> heat sink in the vertical mode. Right now it is in the horizontal "space
>>>> hog" mode. :)
>>>>
>>>> Has anybody on the list ever swapped out the heat sink with another
>>>> version?
>>>>
>>>> Alan Jones
>>>
>>> Not me, but I did add a fan to a Coco3 so that there was significant air
>>> flow through the case.
>>>
>>>
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>
>
> --
> Cheers, Gene
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Yow!  Are we laid back yet?
>
>
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