At 08:59 +1100 12/14/2005, [EMAIL PROTECTED] wrote:
 Date: Mon, 12 Dec 2005 17:47:35 -0600
 From: Jeff Walther <[EMAIL PROTECTED]>
 Subject: Re: [SM] No Chime.

 BTW, if anyone is throwing away a bad PS, I would appreciate the favor of
 snipping off the leads and mailing them to me.  I would, of course, pay
 postage.  With the leads off of bad PSs I can build ATX to S900 adapters
 fairly cheaply.
 Jeff Walther

Jeff, could you run us through the process of how you do the conversion with the leads from an old SuperMac PSU. Thought that might be an easier option myself, but never got round to giving it a try, so tips from a knowledgeable SuperMaccer like yourself would be handy.

Hi Pete,

You can download the instructions here: <http://www.io.com/~trag/Umax_ATX_PS_rev_2.sea.hqx> I think that's a SimpleText files which is a self-extracting Stuff-It file, which is BinHex'ed. So you'll need something to de-BinHex it, such as Stuff-it Expander.

This article is also available on Kennedy's support site.

If you're starting with the leads from a Umax PS, you just need to crimp the pins for the Molex housing onto the wires (remember, one of the Ground pins gets two wires because the Umax PS has one more Ground pin than the ATX PS, and yes it's awkward to crimp two wires on one pin). Then insert the pins in the correct holes in the Molex housing.

The problem is finding that Molex housing (the one that mates with the ATX PS connector, Molex part number 39-01-2201). Unless Digi-Key has picked it up, they're almost impossible to get. The last time I checked the minimum order was for 100 of them. The Model name is Mini-Fit Jr. In the first revision of the article, I wrote that I thought you could use the Mini-Fit BMI housing, but you can't. I misread the specs.

Ah, just checked again. Minimum order is 1000. They're only 45 cents each that way, or another way of looking at it is the first one is $450 and the next 999 are free.

Another option is to buy an ATX extender which are fairly common and generally about $5. Clip the MB end of the extender off and splice those wires to the wires you cut from your Umax PS. That leaves you with one end that plugs into an ATX PS and the other end with the S900 connectors.

The advantage to crimping pins onto the wire and then putting the pins into a new housing is that there are no spliced wires. Spliced wires sometimes lose their tape or wire nut and become subject to shorts, etc. They're less elegant looking and more likely to come loose causing opens.

The advantage to just buying an ATX extender and splicing the wires is that it's fast and easy. The extender is easy to find, and cheap. And there's no finicky pin crimping involved. Just splice the correct wires and you're in business.

For the truly obsessive compulsive, you can buy the ATX extender and try to remove the pins from the housing and then use the housing. There's a little tool that's supposed to make it easier. I think Radio Shack sells it for about $13.

For a really dirty conversion, skip the ATX plug all together. Just cut the ATX connector off of an ATX power supply and splice the Umax wires directly to the ATX power supply wires. This has the advantages of cheapest and fastest, but if you later need to replace the ATX PS, you'll have to do the splice job again.

Needing a second ATX PS sounds unlikely, but I'm on my second one. The first one I got had dodgy disk drive connectors. My drives would lose power in teh middle of operation with the results you'd expect. However, I didn't realize the PS connectors were the problem at first and sent three drives back for warranty replacment, before I figured out that they were spinning up and down because of bad power, not dieing drives. It's mildly irritationg, because the first two were SCSI drives adn WD didn't ahve replacements any more and so was giving cash or larger capacity IDE drives, and I'd really rather still have those SCSI drives. I should have tested them on a different machine.

The details about which wire goes where and all that good stuff is in the above referenced article.

Jeff Walther

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