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Macintosh plus

PostPosted: Sun Sep 12, 2010 9:42 am
by imagineer
I just got a Mac plus, which, when plugged in, went click click bang.
It blew it's C33 capacitor. The web is still pretty rich with information on the old plus and it appears that a comprehensive program of capacitor renewal is required. Is there a sort of acknowledged outlet in NZ for this sort of electronica?

Thanks! John

Re: Macintosh plus

PostPosted: Sun Sep 12, 2010 9:27 pm
by tezza
I find Jaycar a good source of most common caps. For more exotic (which is could be what you might need) I've also used Farnell (http://nz.farnell.com/).

Most caps that cause trouble are electrolytic caps. Replacements don't need to be EXACT. About 20% or so either way is ok and provided the voltage tolerance is no less than the original specified.

I find the hardest caps to replace are those very big ones in old power supplies.

Re: Macintosh plus

PostPosted: Sun Sep 12, 2010 11:14 pm
by imagineer
Thanks tezza. Isn't the net great for stuff like this? I'll be off to Jaycars with my list this week.
I'm really amazed how much substantial information there still on these old puppies on the net.
Yeah, I've read that too about the electrolytic caps, they all need to be replaced on the old plusses. They'll be on the list.
I've read tantalums are a better replacement for a number of the capacitors.
I'm hunkered down for a fight to get this little bitzer going again.
Any idea what might have caused the clicking? ie. what caused the C33 to pop,(it's one of the first caps in the power circuit).
I have some ideas but thought this might be a common problem. You worked on any plusses?

Thanks!!

Re: Macintosh plus

PostPosted: Mon Sep 13, 2010 6:37 am
by tezza
Capacitors simply age. Apparently they contain a paste which hardens over a long period of non-use. When they suddenly get a jolt of current after 20 odd years of dormancy it's just too much and they go poof (usually in a spectacular fashion). The good thing is the faulty component is then very easy to identify and then replace. :)

No, I haven't dabbled with Mac Plus machines but I have played around with later Macs. In some models bad capacitors are a known issue, not from exploding but from leaking. (see http://www.classic-computers.org.nz/blo ... er-fix.htm)

Re: Macintosh plus

PostPosted: Mon Sep 13, 2010 8:12 am
by imagineer
Thankz Tez, will let you know how I get on.

Re: Macintosh plus

PostPosted: Tue Sep 28, 2010 6:19 pm
by gavo
imagineer wrote:I just got a Mac plus, which, when plugged in, went click click bang.
It blew it's C33 capacitor. The web is still pretty rich with information on the old plus and it appears that a comprehensive program of capacitor renewal is required. Is there a sort of acknowledged outlet in NZ for this sort of electronica?


As Tez mentioned Jaycar is normally pretty good, and for those hard to find caps, I've used RS Online - the only problem with RS is that they normally have minimum purchase quantities of 5 - but otherwise seem quite good.

Also, heres a link to a really good repair guide for Mac 128/512/Plus computers - http://68kmla.org/files/classicmac2.pdf

Cheers,