platnicat wrote: > Today I recieved a Macintosh Classic and an SE. The SE is marvelous > and in excellent condition with two 800K floppies AND an aftermarket > HDD with bracket. However, the HDD isn't being recognized in any disk > format utility I tried. The Classic, however, has an annoying problem > where whenever the HDD or floppy is used, the screen becomes jumpy. I > think it's the flyback transformer, but I hope not. HELP!
I had a similar problem on a Mac Plus where in the boot process when it got to using the floppy drive it would restart then repeat the process. The +5V supply was at the ragged edge and the extra load of the floppy motors dipped the +5V line to a point where the protection circuitry triggered a reset. On the plus there is a trim pot on the power supply that adjusts the +5V supply. I connected a voltmeter to a 5V line on the logic board and adjusted the pot so the meter read 5.00V. After that it booted fine. I don't know if the Classic's 5V can be adjusted but you can at least check to see if it's within spec (4.75-5.25V probably). -- 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 a member of 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] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/ -~----------~----~----~----~------~----~------~--~---
