hunt@firqb.dec.com (Phil Hunt) (10/13/87)
>> Within the past 24 hours, my MacPlus, configured with 1Mb of >>DRAM, an external 800K floppy and an external separately powered 40Mb >>SCSI hard disk, has started resetting itself. Most frequently at power-up >>but also after running for periods up to an hour. When it starts, it will >> ....dribble,,,dribble,,, ad infinitum.... I saw the same behaviour when the +5 voltage line goes too low, like below 4.82 volts or so. Pop open you mac, check the +5 voltage line, then tweak the pot until it gets above 4.85. 4.91 is ideal, I have been told. I do not remember the exact pins to check voltage on though, so maybe someone else can recollect. Phil Hunt
gnome@oliveb.UUCP (Gary) (10/15/87)
> >>> Within the past 24 hours, my MacPlus, configured with 1Mb of >>>DRAM, an external 800K floppy and an external separately powered 40Mb >>>SCSI hard disk, has started resetting itself. Most frequently at power-up >>>but also after running for periods up to an hour. When it starts, it will >>> ....dribble,,,dribble,,, ad infinitum.... > > I saw the same behaviour when the +5 voltage line goes too low, like below > 4.82 volts or so. Pop open you mac, check the +5 voltage line, then tweak the > pot until it gets above 4.85. 4.91 is ideal, I have been told. I do not > remember the exact pins to check voltage on though, so maybe someone else > can recollect. > > Phil Hunt Before changing the power supply's voltage adjust setting, be sure to re-seat the connectors that carry the power from the analog board to the logic board. The connector contacts get oxidized after a while and they become (relatively) high-resistance contacts. Pulling the connectors of and plugging them back in should help. Be sure to do the both ends of the cable assembly! If the voltage is still too low (it should be from 4.9 to 5.1 on the logic board) then re-adjust the power supply. You'll need to find someone with one of those long-necked Torx drivers. Gary (Not an employee of Apple Computers -- yet.)