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MX110 Transformer: source for rebuild

K

kmatch

Member
I’ve run into a McIntosh MX110 with a failed secondary on the transformer. One half of the high voltage secondary measures 40 Ohms and the other half is open circuit (high voltage secondary is the red taps).

Audible symptom is that the unit has a hum. I observe a 60Hz ripple on the high voltage cap (C114) rather than the expected 120Hz ripple.

I’ve read some suggestions that the secondary winding on these transformers were wired with insufficient gauge causing the transformer to fail before the primary side fuse blows. I suspect one or more of the selenium diodes failed but I didn’t pull them and confirm yet.

Anyway, I tried tracking down all the usual suspects to get this transformer rebuilt (McIntosh, Audio Classics, Heyboer, etc). Other listed sources for individuals doing vintage audio transformer rebuilds seem to have retired or moved on.

It’s a shame that this beauty of a unit can’t find the right copper coils, insulation and magnetic core to give it another 50 years of life. Is there something I may have missed as a transformer
rebuild source?
 
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Good luck with your search. I had the same problem a few years ago, but the fellow in Maine was still working and took care of my problem.
Have you tried Gery at Transcendar?
 
Reach out to Patrice @clinic-audio

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Terry Dewitt recommended this re-winder service several years ago for my MX110. He did an excellent job but I dont know if he's still around.
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Heyboer has done several for me that have been great. They have done three Mcintosh transformers for me with zero issues. Had one that he rewound the wrong HV secondary on an MPI4 due to miscomunication (vague drawing) on my end and he rewound for cost to fix it. It is a pretty long turn around, but Arwin is the contact person I have and he does a great job.

I will say I have never had to have an audio output transformer rewound from them, just power.

Hope that helps,
Madd0c
 
FYI/FWIW, I think it's Arlyn (contact for Heyboer). Dunno about MX110 but I've ordered a few custom PTs from Heyboer and been pleased with results.
 
kmatch said:
I’ve run into a McIntosh MX110 with a failed secondary on the transformer. One half of the high voltage secondary measures 40 Ohms and the other half is open circuit (high voltage secondary is the red taps).

Audible symptom is that the unit has a hum. I observe a 60Hz ripple on the high voltage cap (C114) rather than the expected 120Hz ripple.

I’ve read some suggestions that the secondary winding on these transformers were wired with insufficient gauge causing the transformer to fail before the primary side fuse blows. I suspect one or more of the selenium diodes failed but I didn’t pull them and confirm yet.

Anyway, I tried tracking down all the usual suspects to get this transformer rebuilt (McIntosh, Audio Classics, Heyboer, etc). Other listed sources for individuals doing vintage audio transformer rebuilds seem to have retired or moved on.

It’s a shame that this beauty of a unit can’t find the right copper coils, insulation and magnetic core to give it another 50 years of life. Is there something I may have missed as a transformer
rebuild source?
Click to expand...

Hello

I didnot come very often these last months but I am very busy working for my customers
Your MX110 is (M) , (X) , (Z) ?
Send me a PM

PATRICE
 
clinic-audio said:
Hello

I didnot come very often these last months but I am very busy working for my customers
Your MX110 is (M) , (X) , (Z) ?
Send me a PM

PATRICE
Click to expand...
Hello Patrice, I have a failed MX110Z transformer in need of your service. Are you still available to assist? It’s not a rush job. Michael
 
kmatch said:
I’ve run into a McIntosh MX110 with a failed secondary on the transformer. One half of the high voltage secondary measures 40 Ohms and the other half is open circuit (high voltage secondary is the red taps).

Audible symptom is that the unit has a hum. I observe a 60Hz ripple on the high voltage cap (C114) rather than the expected 120Hz ripple.

I’ve read some suggestions that the secondary winding on these transformers were wired with insufficient gauge causing the transformer to fail before the primary side fuse blows. I suspect one or more of the selenium diodes failed but I didn’t pull them and confirm yet.

Anyway, I tried tracking down all the usual suspects to get this transformer rebuilt (McIntosh, Audio Classics, Heyboer, etc). Other listed sources for individuals doing vintage audio transformer rebuilds seem to have retired or moved on.

It’s a shame that this beauty of a unit can’t find the right copper coils, insulation and magnetic core to give it another 50 years of life. Is there something I may have missed as a transformer
rebuild source?
Click to expand...
Hello kmatch

You said :
I’ve read some suggestions that the secondary winding on these transformers were wired with insufficient gauge causing the transformer to fail before the primary side fuse blows

no, MCINTOSH LABS never produced bad quality transformers (power, autoformer, output transformers) The problem in MX110 Z is the selenium diodes getting shorted and decrease the life time of the power transformer secondary winding .Many tech and users replace this poor quality diode bridge by a silicon diode bridge with a resistor after replaced the dead power transformer .
In fact the real problem is the design of this secondary winding of this power transformer : this is not fused !! if you get a short with the time (many decade) the winding of this power transformer is working in short circuit (selenium diodes going bad) and can be detroyed after a certain lap of time .If your power transformer is getting hot this is the first sign that there is somethnig wrong in there

PATRICE
 
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