Marantz 250M Power Amp Service Bulletins

Discussion in 'Marantz Audio' started by Pete B, Nov 6, 2018.

  1. Pete B

    Pete B AK Member Subscriber

    Messages:
    2,001
    Location:
    CT, USA
    I found Service Bulletins (SB) 2-5 for the 250M not the 250 in the digital database Marantz (page 10)
    section of AK, they are free for download: http://akdatabase.com/AKview/index.php
    M-250-2 Mar 26, 1975 New part numbers for specific transistors and rules for beta selection
    M-250-3 Aug 16, 1976 Increased reliability by replacing pre, driver, and output transistors.
    Add flyback diodes, bias and test unit.
    M-250-4 Sept 24, 1976 Correction to bias setting in M-250-3, sets current to 1/2 of previous.
    M-250-5 Nov 15, 1977 New part number for power transformer and how to replace a failed one.

    The 250 manuals can also be found there but much earlier in the database.

    Anyone have SB M-250-1 ?
     
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  2. angusdog

    angusdog AK Subscriber Subscriber

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    Hey Pete.I see you are here also.
     
  3. rickl

    rickl Active Member

    Messages:
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    Location:
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    Pete, I have form No. 199-1074. Not sure if this is what you are looking for or this is something listed above.
     

    Attached Files:

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  4. wlhd1610

    wlhd1610 Penny and her new friend Sponsor Subscriber

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    M-250-1 is just about a meter p/n change....
    [​IMG]





    BTW , there are 2 addendums for the 250 amp (which also apply to the 240) are are useful for the 1200 and 250M amps.

    [​IMG]


    Bob
     
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  5. Pete B

    Pete B AK Member Subscriber

    Messages:
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    Location:
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    Thanks everyone for the tips and info!

    Where do I know you from?
     
  6. rickl

    rickl Active Member

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    Location:
    Twin Cities
    SWTP tiger discussions on diyaudio?
     
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  7. angusdog

    angusdog AK Subscriber Subscriber

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    Pete,I am the a newer member of classic speakers pages.I was the guy asking all those recapping questions about AR's,From Montana.
     

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