McIntosh - Hints and Kinks

Discussion in 'McIntosh Audio' started by dewickt, Jul 1, 2004.

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  1. Paul K

    Paul K Active Member

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    113
    Would anybody be able to set me straight on exactly what resistors should be used as replacements in an MC240, should one wish to replace them all while retaining the tone of the amp?
    I kind of need a parts list if anybody has this handy...
    Cap purchase has been taken care of via Jim McShane and I shall be using partsconnexionn as the vendor...
    Thanx in advance!
     

     

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  2. MX117.MC7150

    MX117.MC7150 Listener Subscriber

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    Do you have the service manual? Parts list will give you specifics. Most will be carbon-comp. Any that are not will be listed with particulars.
     
  3. Paul K

    Paul K Active Member

    Messages:
    113
    I do have the service manual!
    Ok does it state exactly what the differences are in resistors for me to order the parts then?
     
  4. DanMid

    DanMid New Member

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    6
    Resistors

    I use metal film or carbon film. Metal film are usually 2% tolerance.
    Both types will last longer than the originals and are quieter. Quieter may mean a different sound??. These amps are so quiet maybe there is no audible difference.
    Replace them all if you value the output tubes. I have two MC30s I just replaced all the resistors and all the caps on. All the caps were leaky and all the resistors were out of tolerance. Dan
     
  5. Paul K

    Paul K Active Member

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    113
    That's what I intend to do...just bought all the parts (now including all resistors) from Jim McShane!
    I will be in soldiering heaven/hell after the holidays!
     
  6. MX117.MC7150

    MX117.MC7150 Listener Subscriber

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    Take lots of 'before' pictures to refer to while working. Can save a lot of angst as you go along.
     

     

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  7. wingzam

    wingzam VIntage audio??

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    Hey Paul,I'll be rebuilding my MC240.Does Jim sell a complete rebuild kit and how can I contact him?
     
  8. Paul K

    Paul K Active Member

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    He does!
    Just google his name and his page will be the first thing that comes up.
    He has both the resistor and cap kits. (He likes K40's)
    Should be about $170 for all parts matched and labeled.
    There are a lot of them!
     
  9. wingzam

    wingzam VIntage audio??

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    Excellent:thmbsp:
     
  10. Paul K

    Paul K Active Member

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    You have to email him though....
    Once he knows what you are looking for he will put it together...quickly!
     
  11. ron-c

    ron-c AK Subscriber Subscriber

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    That C34v is still running perfectly so I guess it is happy!

    Thanks,
    Ron-C
     

     

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  12. brichter

    brichter Well-Known Member

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    MR74: better than MR78?

    Comments/opinions?

    I have heard that the MR78 is the first of the Modafferi tuners, and was the best tuner produced by McIntosh when it was released, this would seem to contradict that.
     
  13. MX117.MC7150

    MX117.MC7150 Listener Subscriber

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    Believe the MR77 was RM's first tuner design for McIntosh. Have read that RM has stated that the MR77 is better for sonics than is the MR78, which is better for reception. There are those who have posted on the FM Tuner yahoo group over the years that think a recapped and aligned (all McIntosh vintage tuners are old enough to need a recap and alignment to sound their best) MR74 is the best McIntosh tuner from a sonic stand-point.
     
  14. brichter

    brichter Well-Known Member

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    Location:
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    Hmm, I guess I'm spending too much time on AC... LOL
     
  15. Rich Andrews

    Rich Andrews Well-Known Member

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    Location:
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    MR73 front end update

    After being frustrated with the low sensitivity on my MR73 I decided to tackle it head on. In the end I succeeded.

    I replaced Q1 and Q2 with a 2N5486 JFETs.

    I also pulled the two crystal filters and removed the plastic cover and then the metal cover under that and tuned the IF coils inside for a 7.8MHZ peak. A quick front end alignment and then the sensitivity exceeded spec. Sounds good too. One of the crystal filters had drifted off to about 7.0 Mhz.
     
  16. dusty-rhodes

    dusty-rhodes AK Subscriber Subscriber

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  17. Rich Andrews

    Rich Andrews Well-Known Member

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    What he did was to electrically break out the receiver into it's basic parts and provided connections on the back panel for each function. While it sounds easy, the devil is in the details.
     
  18. dusty-rhodes

    dusty-rhodes AK Subscriber Subscriber

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    MAC 1700 mod

    Thanks for the info, Rich. It sounds like this isn't something I should attempt.

    Sam
     
  19. Rich Andrews

    Rich Andrews Well-Known Member

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    Location:
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    That task isn't something that the average man-in-the-street could handle. It is one of things that if you have to ask how to do it, you should not attempt it..
     
  20. Martini

    Martini New Member

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    1
    Mc250 power transformer Hum

    Just powered up a mc250 I got a few months ago and the power transformer hums and you can feel it when touched. The amp is quite when no music is playing. Sounds good but I'm worried about the hum. I checked the 2 multi caps and they seem up to spec but I did check the 2 9300uf with my hvac cap meter from work and it only registered around 500uf. The tester goes up to 10,000. I dont know if the tester is reading this big of cap correclty. Any ideas on my situtation. I'm use to working on my tube amps and this is my first solid state I'm working on

    Thanks John
     
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