They can be tested in-circuit with an ESR meter. The sound you describe is a typical failure mode of any switch-mode power supply. I have never run into a bad flyback that prevented the power supply from running, though I'm sure it's possible. All the bad flybacks I ever had caused focus/stability problems, acrid smell, etc.
On Mon, May 24, 2010 at 08:23:36PM -0700, Elliott Price wrote: > Ah, that could well be the case. How can you tell which one(s) are bad? Is > there a way to tell for sure if it is the flyback, or the capacitors? Thanks, > > > -Elliott Price > > Quoit - Macintosh Computer Services > hobbittech.com/quoit > > On May 24, 2010, at 4:44 PM, Ryan C. Underwood wrote: > > > > > If the clicking is rhythmic, and nothing else happens, it is more likely > > that you have dried up capacitors on the analog board that are > > preventing the power supply from coming up. > > > > On Mon, May 24, 2010 at 03:10:36PM -0700, Elliott Price wrote: > >> I have a Mac Plus that I'm pretty sure has a bad flyback transformer. When > >> you flip the switch, it makes a sort of rhythmic clicking, and nothing > >> else happens. I opened it up, and the flyback has white and brown residue > >> on it in certain areas. > >> Can you get new transformers? If so, where could I get one? Or is it > >> better to just get a new analog board? How hard is it to replace the > >> transformer? It looks easy enough to de-dsolder and then drop in a new > >> one. Are there any precautions to take to make sure it's fully discharged? > >> Thanks, > >> > >> > >> -Elliott Price > >> > >> Quoit - Macintosh Computer Services > >> hobbittech.com/quoit > >> > >> -- > >> ----- > >> 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] > >> To leave 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/ > >> > > > > -- > > Ryan C. Underwood > > runderwo(at)mail.win.org > > > > -- > > ----- > > 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] > > To leave 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/ > > -- > ----- > 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] > To leave 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/ > -- Ryan C. Underwood runderwo(at)mail.win.org -- ----- 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] To leave 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/
