"Upgrading and Repairing Your Mac" writes "The Astec power supply used in the Mac IIcx, IIci, and Quadra 700 often fails. One of the symptoms is the inability to start up and the only way to "fix' it is to temporarily unplug the Mac for a while, them plug it back in later. This is due to the failure of a .0033uf/100vw capacitor at board reference C34, which in turn is caused by the capacitor's proximity to a 5-watt resistor that gets hot and stays hot, even when the Mac is powered down. To fix these power supplies, you need to replace the capacitor and reposition it farther away from the resistor. "The .0033uf capacitor may generate a high-pitched (12.5KHz) squeal that some people find excessively annoying. You can substitute a .0022uf/100vw capacitor, which will still work, and will raise the switching frequency of the standby circuit above the range of human hearing." ...............and will keep those Giant Rats of Sumatra at bay.... '-) Hope this is of some assistance in troubleshooting your problem. Jane P.S. If you need help on soldering information, Martin over on the powerbooks mailing list just wrote an *excellent* primer on soldering on Tuesday. Catch it on the archive list at http://mail.maclaunch.com/lists/
[EMAIL PROTECTED] wrote: > "Rich S" wrote: > > >Quarter turn neither prevented the shutdown nor restarted the computer. > >Now, unsuccessful at powering up at all. > > > >Any other possibilities? -- 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> The FAQ: <http://macfaq.binhost.com/> 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/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
