straka@cbnewsc.att.com (richard.j.straka) (12/13/90)
Well it's that time again to discuss Mac Plus analog repair strategies. My 1984 Mac analog board has finally started acting up. When no floppy is in the drive, I get a faint clicking noise at 1 click every 1/2 seconds (yes, I know that the Mac is looking for a floppy at that interval). When a floppy is being accessed, I get a buzzing noise reminiscent of high voltage noise breakdown. I took the case apart, and the noise SEEMS to be coming from the switching transformer (NOT the flyback) made by Astec at the bottom of the board. The noise is NOT coming from the disk drive itself. I suspect that the higher current load is causing a strain on a now marginal transformer. Note that by their vary nature, transformers WANT to buzz; manufactureres have to take care to ensure that they don't. Any suggestions? (yes, I know about SoftSolutions and MicroMat; I haven't called them yet, as I thought I'd get some net wisdom first!) PS: The machine is running 4MB + SCSI, NOT 128K. -- Richard Straka AT&T Bell Laboratories, IH-6K311 --------------------------------------------------------------------------- UUCP: att!ihlpf!straka MSDOS: All the wonderfully arcane INTERNET: straka@att.ATT.COM syntax of UNIX(R), but without the power.