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McIntosh (MC601) amplifier overheating problem

Hello everyone - A buddy of mine has MC601s that have recently started overheating.  Each amp went into protection mode after emitting a burning smell, and both had to have an output transistor replaced (at different times).  

My internet digging has revealed that ThermalTrak transistors are not very reliable, or at least the early batches were not.  Ayre has also reported overheated MX-R amps with the same problem.  They apparently can fail after years of use, which is not good news for owners!

I'm trying to get a feel for how widespread this problem may be (at this point in time)?  Each transistor replacement is $400, and there's an awful lot of output transistors in MC601s...!!  I convinced my brother to also get MC601s so I'm starting to get really worried his will fail too in the near future.

So far, McIntosh's response to my inquiry has been vague and reticent, unlike Ayre who apparently went to great lengths to remedy this issue for their owners.  Has anyone out there had this problem with McIntosh or Ayre?  

aball
minorl
1,016 posts
 
If $400 is the total price and not per transistor, then that is not unreasonable.  $400 per transistor is stupid.  

However, if the tech tested the unit, took it apart and found only one failed output transistor, understand that he/she had to test each one on the side (right or left) that failed, replace it, put the unit back together, test it, package it then yes, $400 isn’t unreasonable. 

Say you you have a stereo amp with push/pull outputs and one side failed.  Most new amps have protection circuitry so the entire amp shuts off and I don’t know which side had the problem.  So I have to disconnect each side separately from the power supply to see which works and which doesn’t.  Now that I know which failed.  There are a few ways to test transistors in circuit.  Non are as accurate as removing each one, testing it and replace the bad ones.  I also have to test the pre drivers because an output driver failing sometimes fails pre drivers. 

My point is that is a lot of work and testing.  If the end result is only one transistor failed (unlikely), it still was a lot of work. Say 2-3 hours labor and if the amp was constructed like a mark Levinson 23.5, then it’s more. Very hard to take apart and remove transistors.  $400 not unreasonable 
minorl
1,016 posts
 
I started by saying it was unreasonable and then thought it through.
aball OP
2,016 posts
 
That's right.
miketuason
337 posts
 
What’s the latest on this aball?
aball OP
2,016 posts
 
McIntosh has gone silent in my attempts to get them to help!  

Ayre took back their amps, and even sent out an RMA for shipping them back (Charlie posted in another forum about it), whether they were under warranty or not.  But McIntosh apparently doesn't care about their customers anymore.  It's so unfortunate.  It seems my friend will be on the hook for having all the output transistors replaced on his dime, despite the fact McIntosh sold defective amplifiers.  I'm guessing it'll cost him $1500, maybe $2000, plus shipping.  It's a big job.  My brother and I also have ThermalTrak amps...I hope they will be ok.
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