McIntosh C20 - can and should I bring it back from the dead?

Discussion in 'McIntosh Audio' started by neevo, Aug 7, 2018.

  1. neevo

    neevo Super Member

    Messages:
    1,524
    Location:
    Sydney, Australia
    I never thought I’d own a McIntosh, so I’m very excited to be posting here! I was overseas on holiday when I saw a post online for some old stereo equipment being sold. One item that caught my attention in the list was a McIntosh. Looking at the photos I didn’t see anything I recognised but 1 item did catch my eye. A bit of googling and it appeared he was selling a C20 Preamp.

    I messaged him but didn’t think I would be able to get in before anyone else as I still had another 2 weeks away and it would likely sell for more than I could afford, despite the condition it was in.

    Well as it turns out we were able to sort a price via messaging and today I went to pick it up.

    I’m here for some advice as I have no idea what I’m getting myself in to and whether my plan to bring it back to life is possible.

    I’m prepared to take my time to fix it up as this will be a passion project. My aim here is to be a quality repair/refurbish and return the amp to as close to original looking as possible. I’m not precious about internals, as long as the quality of sound is preserved, the outside is like as beautiful as practical and my budget affords.

    The good:
    1. It’s a McIntosh C20
    2. Most of the amp looks unmolested

    The bad:
    1. The condition is terrible. Broken faceplate (glass) and also the PO painted the chassis :(
    2. The filter caps have been played with. The metal covers have been removed and not cleanly replaced. The wiring is a little untidy where the work has been done
    3. Rust. Everywhere. Not sure how is best to manage the corrosion. It’s on the chassis, parts of the internals and lots of the bolts, screws and rivets
    4. Ceramic rca’s don’t appear to connect to anything
    5. No tubes
    6. No bottom cover
    7. No case
    8. The silkscreening from the front left panel is gone
    9. The low freq trim plastic pots on the rear are pretty solid
    10. The end of the 4x tag strip near the filter caps has broken
    11. It’s 110v, so I’ll need a step up transformer at some stage

    So I have my work cut out!!!!

    Pics:

    9C4A6759-62E9-4C74-B269-59A6A008945B.jpeg
    821B3DFB-D0E6-4FAE-ACB7-E3E2B42E9EB8.jpeg

    Replaced filter caps:
    86653718-7F4D-4E0D-B6AB-2954485FE9DA.jpeg
    A7E958E6-7277-40C9-9D0E-9C4008F1FDA6.jpeg
    4DB738C7-2107-407A-9A0D-48B61B5DDFFC.jpeg

    The broken tag strip and replaced cap:
    106F732B-8C35-446B-9DE1-4D3F4C26FF55.jpeg
    8B5081CB-46A4-4FFA-8189-85232BDCE865.jpeg
    B97B1268-2DAE-48F8-B465-596513760245.jpeg
    40A69907-1925-48EC-92BB-6C27DB135465.jpeg

    The damaged rca. The final rca doesn’t appear to be connected to anything. Plus the resistors inside are not attached to anything elther
    325A3987-635C-4C43-A677-6D12C9BA7F76.jpeg
     

     

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  2. neevo

    neevo Super Member

    Messages:
    1,524
    Location:
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    The serial number is 3L475

    1C33F729-E43F-4949-9D63-B8DA4BE79C63.jpeg

    There is also another number on the frame 1061:
    F4FC5C2D-E9B3-4310-8A70-643DCBCD34A3.jpeg

    My questions are whether it’s possible to return this amp to a proper working condition? Are parts available? I’ve seen replacement front panels but not sure if they fit the year of this preamp.

    Also is it possible to strip the amp down in parts so I can fix the chassis? It’s not a major need but I’d prefer the amp to be as attractive as I can make it.
     
  3. clinic-audio

    clinic-audio all on YAMAHA untill 1990

    Messages:
    2,312
    Location:
    France
    Hello Neevo

    Everything is possible it is just a question of time and money .
    I do this time to time but don't forget that critical parts (switches and potentiometers ) are in the same shape than your chassis .......
    I don't see anything possible under 3000/3500 $ + many many hours of hard job
    Front glass is not a problem
    Power transformer, electrolytic cap are available , tubes too , and even some potentiometer . I have produced a brand new volume control pot for C20 and it works very well .

    Here is a picture of a C11 (I do not have one of C20 yet)


    C11-inside-view.JPG

    your number 1 061 is a chassis number not a serial number . Your serial number is the one you show in your picture ( 3L475 )
     
  4. One911Guy

    One911Guy Active Member

    Messages:
    113
    Location:
    Saturn
    You are a better man than I am. Gool luck with the project.
     
  5. neevo

    neevo Super Member

    Messages:
    1,524
    Location:
    Sydney, Australia
    Well it sounds like I have a long term project I my hands then. I’ll have to take my time to be able to afford $3k in replacement parts.

    Time and work isn’t a problem as I’ll do most of that myself.

    The amp was reported working when it was stored. Any advice on where to start?

    I’m not sure buying glass and bits are the best investment yet. I was thinking more about replacing the high risk parts and fixing up the replaced parts?

    I also assume the transformer won’t have a 240v tap?
     
  6. John James

    John James "Bob's your uncle" (Stolen) Subscriber

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    Best of luck to you.
     

     

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  7. neevo

    neevo Super Member

    Messages:
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    Looks like I might be on my own on this one...

    @clinic-audio I’ll probably need one of those volume pots as the one I have is clearly not original:

    76BA93FB-9691-477D-B31D-381EF647BE40.jpeg

    I’m committed to getting this thing singing again and in my system one day. I’ve stared the strip and bagging process:

    7BF9F479-7838-4930-8096-0D197CB68B66.jpeg
     
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  8. techguy0192

    techguy0192 Keep McIntosh amps carbon fiber free! Subscriber

    Messages:
    1,100
    Honestly, I'd part that unit out. At lease it would allow some other C20's to live.
     
  9. jkaley

    jkaley AK Subscriber Subscriber

    Messages:
    91
    Excellent project, Sir. If you're doing all the labor yourself, it will only cost about $500 or less in electronic parts including new production tubes. I don't know what the front glass goes for.

    I have a pristine all original c20 from 1961 if you need detailed photos of anything.
     
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  10. darkblue94

    darkblue94 It wasn't me. Subscriber

    Messages:
    9,054
    Location:
    The Pacific Northwest
    I think the best course of action would be to fully restore the electronic functioning using the best quality parts you can gather, replace the front facade & volume pot. After that you should hide that hideous chassis inside a nice proper McIntosh slant leg cabinet. :)
     
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  11. neevo

    neevo Super Member

    Messages:
    1,524
    Location:
    Sydney, Australia
    Thanks all for the comments. I’ve decided that this unit is destined to be brought back from the dead. I’ll never get the chance to own a pristine C20, so the only option is to make one.

    This only owes me $200 so far and I have many hours and years to put in to it to get it to where I want it.

    Thanks in advance to those that help me along this journey, your support is appreciated and I’ll need your knowledge too.

    @darkblue94 i totally agree. Getting it functional is the key priority before the pretty stuff, so I’ll be grabbing replacement caps for the filter supply and seeing where I can get a schematic to work out what’s going on with the RCA jacks too.

    Anyone have any knowledge of the kits on the auction site?

    https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com.au/ulk/itm/382234500939

    This would get me all the caps plus a couple of diodes.

    @jkaley would you be able to take a photo of the filter caps section and the RCA jacks at the end? That would be really helpful for me to know what it should look like :)

    Also looks like a new replacement volume pot is available for these too, so that will get replaced at some stage:

    https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com.au/ulk/itm/152937170257

    I’d also prefer to have this unit on 240v, so I’ll explore the option of replacing the transformer too.
     

     

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  12. Pio1980

    Pio1980 AK Member Subscriber

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    If the fit and function of the level pot assy is satisfactory, I wouldn't worry too much at this time about replacing it.
     
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  13. Champco

    Champco AK Subscriber Subscriber

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    Does it talk? Must be a good story..:thumbsup:
     
  14. neevo

    neevo Super Member

    Messages:
    1,524
    Location:
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    Ain’t that the truth! What boggles my mind is how someone can let a 60’s McIntosh get into such a bad state. Obviously not everyone sees their value (audio or monetary)!
     
  15. neevo

    neevo Super Member

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  16. slow_jazz

    slow_jazz AK Subscriber Subscriber

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    Best of luck to you.

    More than I would ever try to fix.
     
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  17. neevo

    neevo Super Member

    Messages:
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    A bit more investigation has me thinking there’s a bit missing from this amp. So a heavy going through with the schematic is going to be required and a probable Mouser order.

    The bottom doesn’t look to messed with other than the filter caps:

    EDE9E2E6-2CE9-4D19-AEE0-F3458D631CC5.jpeg

    3BFB5622-470E-4B02-9F1D-DF252425A933.jpeg

    509D8C12-F6CC-4DE0-B440-0B3E08587080.jpeg

    The top however I have a few suspicions. But nothing a night with a schematic won’t fix:

    D5BE9FC9-D828-4281-BDF1-831E14DB3D9D.jpeg

    EB602116-FFAB-4AF7-A935-8E0C9D6290D5.jpeg

    Does anyone have any idea of must replace parts in these amps that I can note as I’m making a mousse order?

    Also the more I look at the amp the more I feel I can fix it up. I have found Alu solid rivets which will allow me to completely strip the chassis at some point and I have a plan to save the rear panel with all the lettering and serial number. The rest will be sent away to be stripped and power coated.
     
  18. Bill Ferris

    Bill Ferris Super Member

    Messages:
    2,011
    Location:
    NE. FL.
    neevo, you keep referring that Mac C20 as a amp !
    Are you aware that it is, or what`s left of it, was once a "PREAMP" & not a amplifier ?

    There is a "bit of a difference", I`m just curious if you`re unaware..

    Good luck on this project Sir.

    Kind regards, OKB
     
  19. neevo

    neevo Super Member

    Messages:
    1,524
    Location:
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    Yeah I know it’s a preamp... just can’t be arsed to write preamp each time. Might go with Pre instead :)

    Interesting question from that though. I assume you don’t have to connect something to a preamp when you’re firing it up like you would with a tube amp?
     
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  20. s-petersen

    s-petersen Scott Subscriber

    Messages:
    4,780
    Location:
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    Good luck with your project, yours will be easier than mine was. When I got mine it was missing the entire faceplate, flag pointers and top cover, it took over a year to make the missing parts, or buy them.
    Radio daze has the faceplate possibly.
    Here is mine now, I used the knobs that came with it.
    The top is the resurrected one, the bottom is the one I bought to copy the parts from.
    The parts I made were the flag pointers, side plates to hold the faceplate on, the rear top cover and bottom cover, end caps, and pilot lights.The faceplate and volume plate came from Audio Classics,
    IMG_20160515_155224021.jpg
     
    Last edited: Aug 8, 2018
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