on 19/9/03 11:05 PM, Steve Bell at [EMAIL PROTECTED] wrote: > On 19/9/03 8:31 pm, "Simon Rowlands" <[EMAIL PROTECTED]> wrote: > >> on 19/9/03 12:24 AM, Graeme Finlayson at [EMAIL PROTECTED] wrote: >> >>> Hi folks, >>> >>> I recently bought a Classic II to add to my collection of compact mac's >>> and the seller indicated that it made a noise like an old fashioned >>> kettle boiling on a gas stove - and true to his word it did when I took >>> it out the box. My first suspicion was that the hard drive bearings >>> were shot so I decided to replace the hard disk which has lessened the >>> problem considerably, but it still makes a whistling noise when running >>> - even when the hard drive isn't being accessed. Anybody got any >>> ideas? I'm not sure if I could be looking at a problem with the >>> motherboard or not as the drive I installed was a known good, silent >>> runner on a Mac SE just before I put it in. >>> >>> Any advice or ideas appreciated! >>> >>> Cheers, >>> Graeme >>> >> >> You don't say wether or not you have a normal sceen(full width and height) >> if you have it is possible for the whistle to be what is otherwise described >> as "ringing" this may vary slightly as the unit warns up and can be caused >> by nothing more sinister than slighly loose windings of wire on chokes or >> transformers around the " line output stage ". >> >> If all this sounds like jibberish take it along to any tv repair shop and >> get them to have a listen. >> >> A cure can sometimes be effected by coating offending winding (if the wire >> is exposed to the air) in an epoxy resin making it sort of encaspulated. >> >> hope yhis may be some help. >> > > This is the most likely cause based upon whistling from some iMacs and older > monitors I've been involved with. I've had CRT yokes causing this on > Multiple Scan 20's, and flyback transformers on the M1212 monitor, and power > supply transformers in iMacs. In almost all cases either epoxy or gel type > superglue used with the spray can stuff to set it instantly cured the > problem if applied between the joins in the ferrite core. Sometimes prodding > the suspect part with a piece of wood will reduce the whistling proving it > to be the cause. Other possibilities can be defective electrolytic > capacitors in power supplies, these can cause spurious oscillations causing > the transformer to whistle. > > Steve Bell >
I delberately did not get too specific about prodding about to try and isolate this fault because of the safety issues. There are some VERY high voltages about and if you don't know which bits to avoid BEWARE. Simon Rowlands -- Mac UK is sponsored by <http://lowendmac.com/> and... 123Inkjets.com <http://lowendmac.com/ad/123inkjets.html> Support Low End Mac <http://lowendmac.com/lists/support.html> Mac UK list info: <http://lowendmac.com/lists/mac-uk.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/mac-uk%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
