New to me C32 and an MC2105. Hooray!

[Searing75]

I am in the game folks! Loving the sound. Too much hiss though. Changing all the electrolytics as we speak in the 2105. The C32 will have to wait. It looks good inside though. The ribbon cables are fine. Elna, nichicon, and some Panasonic going in the 2105. Soooo heavy!!! My poor surgically repaired back is angry! Pics to follow.

And, there goes the O ring in my downstairs toilet. Ugh. Gotta' fix that first today, then back to my new toys!

 

[wajobu]

I've had both. The MC2105 is a great sounding amp--as you note, a HEAVY beast...I've moved a couple around. I had mixed results with a C32, but an extremely versatile machine, including the top mounted monitor amp, which IIRC, has an output of 10 WPC alone, so, the C32 can be used a a stand-alone amp in certain situations.

Have fun!

 

[CohibaJoe]

I've had both. The MC2105 is a great sounding amp--as you note, a HEAVY beast...I've moved a couple around. I had mixed results with a C32, but an extremely versatile machine, including the top mounted monitor amp, which IIRC, has an output of 10 WPC alone, so, the C32 can be used a a stand-alone amp in certain situations.

Have fun!

For C-32...I did a Complete Recap and Op-Amp replacement...:http://audiokarma.org/forums/index.php?threads/mcintosh-c32-recap.702569/

It will need NEW cables. Volume control is also an issue and the HeadPhone Monitor Relay had Cold Solder joints. Make sure you go thru each Joint.

 

[Searing75]

The C32 sounds great. The cables are dry, but fine. The record switch is loose/wobbly. It's mounted to a circuit board, and the whole assembly moves inside. As of now, I am not using it, but will fix it eventually. I will recap the preamp as well.

I just recapped the 2105. Well, most of it. Still need caps for the drivers and the multi can. Probably just do separate caps in place of the can? Unless there is a source for that can? I used deoxit on all controls. The hiss is gone, and the amp sounds wonderful. Someone had replaced a resistor on one of the driver boards with two resistors in parallel that were both the wrong value. I replaced them with one of the correct value. So much fun!

 

[Searing75]

IMG_0673

• Searing75
• Feb 26, 2017

My C32 and MC2105.

 

[Searing75]

The barrier strips were cracked between the terminals, and shorting was probable. So, I unsoldered the 4 and 16 ohm taps from th inside. Capped off the wires with twist caps, and stuffed them down inside. Now, there is no chance of shorting the speaker wires onto other taps.

Also, anyone know how to get the multi cap can off it's Mount?

 

[Searing75]

One of the transistors is a Sylvania ECG 181. I assume that's an okay substitute for the Motorola's?

 

[c_dk]

If memory serves me correctly, the Sylvania and Philips generic replacement semiconductor business was absorbed into ECG twenty years ago, and went out of business over ten years ago. The replacement of a single output device was not a recommended procedure by Mac warranty service centers, even if using a sub that passed Mac engineerings scrutiny and was therefore sold by Mac parts.

When the Mac blessed devices became the Motorola MJ15003 it was a absolute to replace all the outputs when one failed. This still holds for the now used Onsemi MJ1500G device today.

The Sylvania has been in your amp for decades I understand.......I however would replace all the outputs with the new Onsemi device and make sure the wirewound emitter resistors are the correct inductive units. While it is open it might as well be done right.

This and driver board updates has been covered in prior MC2105/2100 posts that can be found with a search and a service manual is available in the Akdatabase.

 

[Searing75]

Thanks C dk. I went ahead and ordered the 12 MJ15003's, and all of the amps 5w resistors. What about the semiconductors on the driver boards? They all look original to me. I would assume they are fine for now.

 

[c_dk]

You need to search for and read the past threads.....I would not replace the original Rockwood or Cober resistors unless I absolutely had to. Modern WWs have too little inductance than the originals and their haphazard replacement can cause circuit instability and oscillation.

The past threads also highlight the driver board upgrades for the whole family of amps that use the same boards, that is the MC2300 and the MC2105/2100.