Commodore 64 Power Supply

[Jim Brain]

Roy J. Tellason wrote:
> On Tuesday 01 July 2008 14:00, Jim Brain wrote:
>   
>> Late in the game, CBM switched (no pun intended) to switchers.  I have a
>> C128 PSU that is a switcher.  They were mounted in the same case, but
>> you can tell by the weight.
>>     
>
> I don't recall ever seeing a 128 PS that wasn't a switcher.  The 128D had it 
> inside the case with the computer,  rather than separate in a "brick",  but 
> it wasn't that different,  just a little more spread out.
>
>   
OK, I stand corrected.  I finally got home tonight, and was smug enough 
to go out and pull the units.

First, the lightweight PSU I have with a C128 is not a C128 PSU at all, 
but a A500 PSU.  I am sure we tested the PSU with a C128 last week (we 
were going through the units prior to the C4 CBM EXPO this past 
weekend), but I'll have to check.  The reason's it is so light is it 
only provides DC on the outputs.  5 and +-12.  It simply chops mains to 
get what it needs, I would guess.

The other C128 PSUs are heavy as a common brick, and Roy looks to be 
right.  They have what looks like a switcher under the huge transformer. 

My apologies for the incorrect information.  I would assume the C64 HD 
PSUs (being the same as the C128 PSU, just a different plug, use the 
same switcher design.  I could swear, though, that the older 
non-serviceable 64 PSUs  are not switchers.

I have somewhere here in the stash a schematic for a MA701 PSU, that 
looks to be a HD linear for the 64.  I have a couple of the units.  Is 
the OP looking to just buy one, or is the design the big thing?

Jim

-- 
Jim Brain, Brain Innovations                                      (X)
brain at jbrain.com 
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! 
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