Doug McNutt wrote: > At 06:37 -0800 12/1/08, DavidV wrote: >> Thanks for the reply Dwight >> >>> Check the pram battery, it may be bad and that can cause all types of >>> problems. >> Yes, the pram is dead (not too surprising as the Mac hadn't been >> turned on in years). But that isn't the main problem as I unplugged >> the power supply from the motherboard to measure its output (and got >> the obviously incorrect voltages mentioned in my original post). If I >> can get the power supply up and running or replaced then I can deal >> with the pram later on. > > Some Macs - The MacII and the IIFX for sure - require the PRAM > battery to provide a 5 volt pulse that starts up the power supply. > One of those colored wires may be expecting +5 volts as an input to > start it up. The MACII supply used a white wire for that. It > wouldn't hurt to try momentarily applying +5 to any pin.
The LCs do not have soft power. They are turned on by a rocker switch on the back of the case. A dead PRAM battery won't prevent them from starting up but it will prevent them from displaying video and booting. There is a simple bypass to a dead PRAM battery on most Macs so afflicted. Turn it on, give it a couple of seconds, then quickly flick the power switch off and on again. Another method is to turn it on then give it the three fingered salute, Command-Control-Power on the power supply. As to the original poster, many switching power supplies can be damaged (as in totally broken) by powering them up with no load. I don't know if the LC series is that way. I lost a power supply in Q660AV when I replaced it and forgot to plug in the DC power cable. -- Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/vintage-macs?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
