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Marantz 1090 - Need help identifying replacement resistors on Main Amp

Discussion in 'Marantz Audio' started by Hartin, Nov 1, 2018.

  1. Hartin

    Hartin New Member

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    1cKfM2g4j6mJ8F37as40kVhJKWjCl2bBm4hqtERsOwwpX92IB.jpg Hi Marantz Junkies. I could use your help with a 1090. I've got a pdf of a service manual that doesnt seem to match up with what I'm seeing. I'm looking to ID some resistors on the Main Amp PCB. The PCB and Service manual both have them marked as R762 and R774. R762 is the green and R764 looks teal in the pic

    R764 (teal, on the right) looks to me to be a 100 ohm resistor with a 5% tolerance. The copy of the manual I have lists R764 as .47 ohm 2W with a 10% tolerance. I do not know if this is an original component. I can tell that other components have been changed previously.

    R762 (green on the left) has me stumped. I'm having trouble identifying it by its bands. The manual has it as 100 ohm 1/2W with a 5% tolerance.

    The attached pic is from the right channel, the left channel was smoked so I cant use those as a reference.

    Can you guys help me ID these? Also, can you help suggest a replacement composition? I'm guessing they're metal film but I dont know how to tell the difference.
     

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    Last edited: Nov 1, 2018

     

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  2. MBuras

    MBuras Restoration is an Addiction Subscriber

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    R762 and R764 are both 100 ohm. Listed as 1/2 watt but look a little big so maybe 1 watt to be safe. Metal film or carbon film - your choice. And tolerance 5% or better.

    I posted some pics a while back and you can see the teal resistors you’re referring to in the amp board image.
    http://audiokarma.org/forums/index.php?threads/marantz-1090-notes.794718/

    You also started by saying R764 and then switched to R774. R774 is one of the 4 wirewound cement emitter resistors surrounding the area you’re talking about. They look like big white rectangles.

    Hope that helps.

    Mike
     
  3. Hartin

    Hartin New Member

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    Good catch Mike, Thanks! yes I haven't moved on to the cements yet. Its no wonder I'm mixed up... the manual I have has them backwards. or at least marked differently from the PCB
    upload_2018-11-1_15-38-11.png
     
  4. MBuras

    MBuras Restoration is an Addiction Subscriber

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    Location:
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    Aha! You got me. Manual is correct. 761/762/773/774 are 100 ohm (the teal resistors). 763/764/765/766 are 0.47 ohm (the cement resistors).

    Mixed me up something good. Brain needs a rest. :rolleyes:
     
  5. Hartin

    Hartin New Member

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    11
    This is the part of the manual that is getting me messed up. This table has been copied from the Service Manual Parts List for the Main Amp Board. It lists the board as a P700 but it doesnt look like the other pictures of P700's online.
    The descriptions of the highlighted resistors don't match up with the actual bands I'm seeing on the resistors. I think I'm going to chalk this one up to an incorrect parts list unless someone can shed some light on these inconsistencies.
    upload_2018-11-2_10-5-26.png
     
  6. MBuras

    MBuras Restoration is an Addiction Subscriber

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    The manuals are notorious for errors and I definitely think you’ve found a few. The 1090 also underwent revisions not mentioned in the manual. Mine had a few different parts than another member.
     

     

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  7. Mike Sweeney

    Mike Sweeney AK Subscriber Subscriber

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  8. Hartin

    Hartin New Member

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    Can you guys give advice on suitable replacements for the cement resistors on the emitter side of the output transistors? The parts list has them at 470 mOhm 10% 2W.
    Cant say I know much about emitter resistors at all.
     
  9. petehall347

    petehall347 the brandy coffee man Subscriber

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    i doubt the value very much . be more like 0.47 ohms at a guess
     
  10. ChrisMarantz

    ChrisMarantz AK Subscriber Subscriber

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    I like something like these Vishay resistors - Chris
     
  11. petehall347

    petehall347 the brandy coffee man Subscriber

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    sorry not used to milliohm
     

     

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  12. Hartin

    Hartin New Member

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    almost done with my list of repair parts. On to capacitors, or capacitor rather. This guy got fried by the neighboring resistor that flamed out. I've also attached a pic of an original that isnt fried.
    How does this look for a replacement? https://www.mouser.com/ProductDetail/?qs=zcDUcsVsD8HTo7bn7i0hFQ==
    Better options?
    20181108_210541.jpg
     

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  13. Leestereo

    Leestereo Super Member

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  14. Hartin

    Hartin New Member

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  15. Hartin

    Hartin New Member

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    Lastly for repair part ID's: these transistors. From my reading these are pretty rare but can be found on www.littlediode.com
    If I've tested these correctly they're shorting between the emitter and collector and need to be replaced.
    Blue is a NEC B618 and Black is a NEC D588
     

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