McIntosh MA6100 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th May 2010, 10:25 PM   #1
diyAudio Member
 
antiquekid3's Avatar
 
Join Date: Feb 2010
Location: Alabama
Default McIntosh MA6100

Hey guys,

I might have a chance to buy one of these power amps. However, one channel is blown. It seems to have been well taken care of over the years, though.

What would one of these be worth restored? How hard would something like this be to diagnose and repair? I've been working with electronics for at least 10 years and know a fair amount of tube and solid state stuff (though I still have a lot to learn!)

Thanks in advance!

Kyle
  Reply With Quote
Old 27th May 2010, 01:00 PM   #2
Orit is offline Orit  Italy
diyAudio Member
 
Join Date: Feb 2007
Location: Milano
Worth repairing ? Definitely yes, as its value in working condition can be in the 500 Euros region, even if this is the most sold classic McIntosh and even if its sound is not, in my opinion, one of the best.

My father bought it in 1974, and it's still working fine without any service other than de-oxit. Very easy to service thanks to plug-in boards, the service manual is easily downloaded from the web, and it's curious to find European components inside (Philips capacitor, Austrian electros, etc).

But be very careful about the front panel: it's glass and spares are VERY costly !
  Reply With Quote
Old 2nd June 2010, 01:35 AM   #3
diyAudio Member
 
antiquekid3's Avatar
 
Join Date: Feb 2010
Location: Alabama
I got it! With some Klipsch Heresy speakers...all for $350! Unfortunately, the McIntosh faceplate is broken...and it definitely has some electrical problems, according to the owner. Oh, well! One Klipsch needs a new tweeter diaphragm and the other a new woofer. But I think I did pretty well for $350!

Anyone have a manual? Where could I get a new faceplate?

Thanks!

Kyle
  Reply With Quote
Old 2nd June 2010, 05:51 AM   #4
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
http://www.berners.ch/McIntosh/Downloads/MA6100_ser.zip

For glass try Audio Clasics, NY, or direct from McIntosh.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 2nd June 2010, 08:54 PM   #5
diyAudio Member
 
antiquekid3's Avatar
 
Join Date: Feb 2010
Location: Alabama
Alright, I have located a front panel. They are so darn expensive!

I'm in the process of cleaning up and figuring out what is wrong. I've found that two of the 5A fuses are blown. I also found that both lower transistors (Q415 and Q416) are dead. The two upper transistors are just fine. I also noticed that the two left transistors have been replaced at some point because the part numbers and date codes don't match.

What do I need to replace the transistors with? Where can I find them?

Before I go powering this unit up, I'd like to know what fried the transistors to begin with. Since the two transistors that blew were attached to the positive rail voltage, I'm wondering if something happened there. But I'm not sure...

Kyle
  Reply With Quote
Old 2nd June 2010, 11:15 PM   #6
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
30 year old amplifier, you expect the parts to last forever?

Check the drivers and the bias circuit too.

Use MJ15003 for outputs, replace them all.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 3rd June 2010, 12:13 AM   #7
diyAudio Member
 
antiquekid3's Avatar
 
Join Date: Feb 2010
Location: Alabama
No, of course I don't expect parts to last forever!! However, now that I know some of the history behind the amplifier, it does seem as though it's had a rough past. The guy who had it after his dad gave it to him used it to play (c)rap through at college. It's not a wonder some of the fuses and outputs are blown!

Can I check the driver and bias circuits without the outputs installed? Will the voltages be pretty close?

I did check the power supply by removing all of the fuses. It's right on 46V, which is pretty close to the 42.5V as indicated on the schematic. Is that appropriate?

Kyle
  Reply With Quote
Old 3rd June 2010, 12:19 AM   #8
diyAudio Member
 
antiquekid3's Avatar
 
Join Date: Feb 2010
Location: Alabama
Digi-Key - MJ15003GOS-ND (Manufacturer - MJ15003G)

Are these as good as anything?

Kyle
  Reply With Quote
Old 3rd June 2010, 01:21 AM   #9
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
Those are the ones, and a safe place to buy from.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
McIntosh tweeter - what to do with it? plenk Multi-Way 0 18th August 2008 07:47 PM
McIntosh MA6100 Hornboy Solid State 6 9th November 2005 07:42 AM
Repairing an old McIntosh namui Solid State 3 4th May 2005 12:35 PM
Marantz MA6100 monoblocks griff Solid State 2 15th February 2002 07:52 AM


New To Site? Need Help?

All times are GMT. The time now is 09:10 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2