[G4] G4/400 AGP Power supply. Which one? Good source?

[k]

At 12:04 PM -0400 24/5/03, John Erdman wrote:

>Maybe that's the wrong question... does it make a difference technically?
>If the pinout voltages the same on both units they ought to be
>interchangeable. But I don't have any manuals to refer to for the two
>supplies and the Apple site isn't much help. )

I've found Apple to be deliberately obstructive when seeking any 
information whatsoever on power supplies. Basically what they want is 
for you to return the broken unit to them and pay their (high) price 
for a replacement. They keep closer hands on power supplies than any 
other component, to stop people from recasing Macs.

>	Early AGP's were powered with a 208 watt supply and later ones with
>a 237 watt.  I found a reference at HardcoreMac that suggested that the
>237W supply is used with Rev 2 motherboard and beyond. I inferred from this
>reference that it is important not to get the wrong power supply (for what
>reason?).   However, I seem to have a 237W supply and my motherboard is a
>Revision 1 (I think).. I'm wondering whether this contributed to the early
>death of my machine.

If this were the case, the board would have been damaged by the 
incorrect voltages rather than the PSU flaking out on you. If this 
happens to you a lot, I'd advise getting a UPS that does filtration.

>	Does anybody know of an authoritative source for figuring which one
>I should be using? Or if it matters.

I strongly doubt that it would matter.

>	I'm also having trouble locating a source for the power supply.
>Suggestions would be appreciated.

If these are the 22-pin G4 PSUs you're looking for, if you find a 
source that will sell you one without a broken one to exchange, 
please tell me. Selling PSUs that can run G4s seems to be grounds for 
Apple turning its biggest legal guns on you - it can lose an Apple 
reseller its license, and Core Computers (who make case kits for G4s) 
recently signed some kind of deal with Apple that prevents them from 
selling any individual componentry. It now has to come as a kit which 
is not a lot cheaper than a store-bought Mac.

Another thing that would be very helpful to me personally is a 
diagram of the pinouts on the 22-pin unit. 24-pin MDD units are 
common and cheap on eBay ($20 where the 22-pins are rare and cost as 
much as $200) but the form factor is totally different, so no help to 
you if you just want a relacement. I am doing a fairly radical 
casemod, though, so form factor is not an issue. If I could find the 
pinouts for a 22-pin supply I could probably alter a 24-pin unit to 
suit - I'd guess there would be two redundant lines. ATX and 2-pin G3 
supplies can't be easily altered in this way as they lack the correct 
line out for the FireWire bus power.

Sorry if this is not much help, I guess I'm really just saying this 
is an interesting topic, so please post any developments.

Cheers, k.
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