[Coco] CoCo 3 Voltage Regulator heat sink

[Mike Pepe]

While both of those options may reduce power consumption to some degree, my real world experience suggests the best way to deal with the CoCo 3 heat problem is to stick a 40mm fan near the PSU area. I've had a 512k/6809 CoCo running that way for years and years without issue. (Except maybe a little noise.)

If you're going to mess around with the PSU, I'd just (and have) take the Gene approach and just rip out the PSU entirely and run the thing off an external unit. I recycled an external switcher from an old dead Telebit router and used it for a CoCo 3/Disto 2MB repack.

-----Original Message-----
From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On Behalf Of Stephen Adolph
Sent: Thursday, April 09, 2009 6:35 AM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] CoCo 3 Voltage Regulator heat sink

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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>

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