Obsolete Power supply circuit diagram

Question

Obsolete Power supply circuit diagram

Hello everyone

I have 2 G4 gigabit ethernet (1 DP 450 and 1 SP 400 that I use as spare parts for the first one) and both power supplies have failed. Since these are obsolete, it gets harder to find parts for them, so I'm trying to repair the power supplies myself. I found some resistors that heated a lot, and a broken capacitor. I manage to replace them although I'm not sure of the resistor values and brought one psu back to life, but the other refuses to do anything. It would be easier to troubleshoot if I had the circuit diagram of the psu. Does anyone know where I might get it? The manufacturer (AcBel) sent me to Apple, but they don't seem to have support for this kind of request... The model number is : API-9841-291. Both have rev. B hardware.

Thanks in advance

Mac Pro 8 core Xeon, Mac OS X (10.6.4), 6 gb ram, Radeon HD4870

Posted on Sep 7, 2010 6:10 PM

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Answer 1

Best reply

BDAqua

Level 10

239,105 points

Sep 7, 2010 6:40 PM in response to Castor Bricoleur

Hi Castor, are you aware you can convert an ATX PSU to the Gig or other G4s?

http://www.atxg4.com/gige-da.html

Apple's Pinout anyway...

http://docs.info.apple.com/article.html?artnum=95064

These people likely have a diagram, that you'll not likely get...

http://www.acsindustrial.com/repair-catalog/item-17366.html

A working one for $40...

http://cheapmaccomputers.com/power_supplies.htm

But none of what you really want, sorry.

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Answer 2

Sep 8, 2010 5:49 PM in response to BDAqua

Hi BDAqua,

Thanks for the help, I think it will be hard to find the circuit diagram... The problem is that buying a used psu means it could fail at any time and refurb one are not cheap...

Seeing the ATX conversion got me thinking. Although the diode trick is a good idea, the forward voltage drop of the diodes means the mb gets 4V in sleep and 11V when On, explaining the problems with deep sleep and firewire. Then I found this for 35$ on Digikey :

http://us.tdk-lambda.com/lp/ftp/Specs/zpsa40-60.pdf

I will use this psu to provide always on 28Vdc and an ATX psu salvaged from a defective PC at work to provide the other voltages. The best part is that the holes on that board will likely align with the holes on the empty HD rack on the left! A couple of screw and extenders should do the trick.

However, this 28V psu can only output 2.14A, so powering an ADC monitor is excluded, but should be enough to use the firewire ports.

I'll keep you posted on how it turns out.

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Answer 3

BDAqua

Level 10

239,105 points

Sep 8, 2010 7:24 PM in response to Castor Bricoleur

OK, looking forward to hearing the outcome. 🙂

My BBS has a few HW people on it, it's the remnants of the old xlr8yourmac BBS...

http://x704.net/bbs/

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Answer 4

Sep 14, 2010 7:08 PM in response to BDAqua

Good news, my plan B worked as expected! I rewired the ATX power supply so the pinout will match the G4's and used my little 28Vdc power supply to provide the required voltage. The mounting holes of the 28Vdc power supply did fit on the HD rack, so no rework was required. I ran the AC line from the ATX psu, so there is still only one power cord required.

Now, for the tests. I've ran it a couples of days now and it's still running fine. No problems with deep sleep and my external firewire DVD-RW worked fine. I didn't try an ADC monitor since I know that the 28Vdc is not powerfull enough to power it...

If you want more information on how I did it you may contact me. I also took a couple of picture of my work.

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Answer 5

BDAqua

Level 10

239,105 points

Sep 14, 2010 7:12 PM in response to Castor Bricoleur

Good news, thanks for the report, good work too! 🙂

If you want more information on how I did it you may contact me. I also took a couple of picture of my work.

No way to do it, your eMail is hidden in your Profile.

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Answer 6

Sep 14, 2010 7:19 PM in response to BDAqua

Oups, my bad :P

It's ok now 😉

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