Repairing an old Mac Amp

[diyman]

I am trying to salvage an old Mcintosh MC2100 Amp that has been hit by a power search. Can anyone ppls let mw know the commercial numbers of the Mc parts Nos. 132-038 and 132-039? If these are discontinued, any new replacements?

 

[Nelson Pass]

If you are referring to the output devices, I
previously have had some luck using the Motorola
MJ15022 and 24 for the NPN and the 23 and 25 for
the PNP.

 

[djk]

The outputs in a MC2100 are all NPN and are closest to an
MJ15003.All the smaller transistors are available from McIntosh at reasonable prices.Before you do anything though, make sure the power transformer is OK.The 6.3V winding that drives the pilot light is not fused.If the light shorts out when it goes (a common occurance) the 6.3V winding will overheat and short out the entire transformer. The transformer is no longer available from McIntosh.

 

[diyman]

Thanks guys for the tip. I've earlier changed the o/p device of one channel to MJ15003s and it works fine but the devices that I mention are N and P channel transistors driving the output devices of the other channel. The originals are TO5 packings that comes together with a heatsink and I believe the devices could be RCA 40409 and 40410. These devices come attached with exactly the same heatsink as those in the Mac. The voltage specs seem to be quite suitable. I've checked with Macintosh and was informed the original parts were discontinued and offered a modification kit which is somewhat expensive. Anybody know of any commercial equivalents that I can install without having to modify the curcuit? Could do with some help here.

 

[djk]

PNP
RCA 40409 .7(Ic)/90(V) TO-39
Driver Transistor w/heat sink
RCA 40410 .7(Ic)/90(V) TO-39
Send us an email to dealers@magicparts.com and include your zip code in your subject line. We will promptly reply with the dealers in your area.

Expensive but still available.An alternative is to use the 2SA1306/2SC3298 pair with TO-220 heatsinks.Watch the pin-out if you do this.About 1/10th the price.


[Edited by djk on 12-05-2001 at 04:57 AM]