At 01:43 -0400 8/19/05, Powermac wrote: >So what are the basics for PS repair (is there a PDF or book on the >subject)?
The technology of switching power supplies is one of the fastest growing areas. Chips and operating frequency improve daily. The best starting point is a schematic for the supply but, especially from Apple, it will probably not be available. If you can read the part number from the controller chip you can get suggested circuits from the manufacturer of the chip. It's often on the web as PDF's. Be careful buying a book to be sure it covers the correct decade. But hear this: A REQUIRED piece of equipment is an isolation transformer capable of supplying ungrounded AC power to the supply being repaired. That will allow you to examine the input side circuitry of the power supply with grounded equipment like an oscilloscope. Most supplies start with a voltage doubler that produces about 350 VDC on the power transistor and it's negative side does not correspond to earth ground. Probing around with such a supply plugged directly into the wall is a good way to burn out a meter or get a nasty shock. Also: Switching power supplies usually require a load at least on the 5 volt output to operate correctly. You'll need to draw a couple of amps with a, say , 3 ohm power resistor which will get hot.. -- --> From the U S of A, the only socialist country that refuses to admit it. <-- -- Vintage Macs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> Vintage Macs list info: <http://lowendmac.com/lists/vintagemacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[email protected]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/vintage.macs%40mail.maclaunch.com/> iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com
