McIntosh C28 With Bad Transformer - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 20th November 2012, 05:51 PM   #1
diyAudio Member
 
Join Date: May 2012
Default McIntosh C28 With Bad Transformer

I have owned my C28 for about 4 years now but recently had to take it in to my audio tech for repairs. He has diagnosed a bad transformer and states that it needs to either be replaced or re-wound. He told me that to have it rewound, it would cost about $800 and otherwise doesn't know where to find an original transformer to replace it with (None available through McIntosh). This unit is in excellent condition with a perfect faceplate...near museum quality so I would really like to have it repaired but $800 to have the transformer re-wound is more than what the unit is worth. Anyone with any ideas on how to proceed?

Thanks in Advance
  Reply With Quote
Old 20th November 2012, 05:57 PM   #2
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Moved to analog line level section.
  Reply With Quote
Old 29th November 2012, 05:55 PM   #3
diyAudio Member
 
Join Date: Apr 2010
Location: Coffs Harbour
The options for keeping it original have already be covered by your repairer. Short of someone having a unit with a working transformer that they are prepared to sell as a donor preamp, rewinding is all that's possible, though $800 seems err..inflated.

If you are prepared to fit other parts, the necessary voltages could be supplied by standard transformers that fit in the available space. Only 12-0-12V AC and 5V AC windings are needed from that but a low current, 150V or even a 75V winding transformer (which is likely the blown winding) would be necessary whether the original transformer remains in place or not. That should still be obtainable from any transformer manufacturer in a low enough current rating to keep it small. Alternatively, a complete substitute transformer could be made for less money.
__________________
regards
  Reply With Quote
Old 29th November 2012, 06:13 PM   #4
diyAudio Member
 
Join Date: May 2012
Default Economical Transformer Rewinding Service

After not receiving any replies here for several days to my query, I contacted several reputable McIntosh restorers with my problem. Received a very useful referral from Terry DeWick who told me he had a C-28's transformer re-wound by this company last year and that they do quality work. I'll be sending mine to them. $155 to rewind the C-28s transformer. Here is the link :

McIntosh
  Reply With Quote
Old 30th November 2012, 07:46 PM   #5
diyAudio Member
 
Join Date: Sep 2011
Location: Texas
Are you sure that the transformer is the only thing that is bad? It is very unusual for a transformer to die. I have a bunch from decades ago that have been through a ton of stress that are still chugging along happily.

If your transformer is really bad, I would double check everything else in your amplifier because other things are probably broken too. Imagine what would have to happen to damage a solid rod wound with copper... very unusual.
__________________
2X Com-tech 400, Improved Headphone Amplifier
  Reply With Quote
Old 1st December 2012, 06:30 PM   #6
diyAudio Member
 
Join Date: May 2012
Thanks Techbiker,

I'll keep that in mind and make sure that the whole thing is looked at carefully before powering it up with the newly re-wound transformer.

Bill
  Reply With Quote
Old 1st March 2013, 09:11 AM   #7
diyAudio Member
 
Join Date: Nov 2012
I understand the booster transformer is used in auto mode to match the load. If your speakers are 8 ohms or more, then the transformer is probably not necessary. In an extreme case, to increase the load capacity can try to upgrade and install additional output transistors.
  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 C28 and MC2105 dukep Solid State 9 5th November 2012 02:41 AM
Mcintosh C28 Karrry Solid State 1 28th April 2009 03:06 PM
McIntosh transformer turns ratio SpreadSpectrum Tubes / Valves 8 27th December 2008 09:50 PM
Volume control on McIntosh c28 Preamp howches Everything Else 2 12th June 2007 07:08 PM


New To Site? Need Help?

All times are GMT. The time now is 01:11 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