Marantz 2270 works for 5 mins then click off

Discussion in 'Marantz Audio' started by Marc1234, Jun 9, 2018.

  1. Marc1234

    Marc1234 New Member

    Messages:
    33
    so not new to electronics but new to audio gear. I recently replaced all caps as a few were bloated on the p-800 board I also replaced all suggested caps mentioned with exception of the 2 MAIN 55v 9000uf caps in another one of your forums on here which by the way are extremely helpful..! So I figured it wouldn’t hurt all the way down to the p-400 board marantz 2270 unit is serial # 32xxx after about 5 to 10 mins with no speakers attached voltage “bias” creeps up enough to kill speaker relay this unit did not work when purchased knowing I was going to rebuild it. After replacing caps the unit works sounds ok then relay shuts off measured voltage on j-802 45vdc creeps very slowly upwards j-801 20vdc creeps up slowly eventually killing the relay both are too high I understand that’s why I am probing your guys expertise I have r809 turned all the down..! I have also checked diodes with 1 leg out of circuit for push all seem good. I have checked from j-803 to chassis “0” and with unit on “0” I do not have access to a scope any help would be fantastic thanks.
     
    Last edited: Jul 7, 2018

     

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  2. willyrover

    willyrover Super Member

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    Not an expert here but I'll start things off.

    From what I understand your 35V on J802 starts at 45V and drifts up and your 13.5V on J801 starts at 20V and drifts up. R809 is set as low as it will go.

    Is the unit set to the correct mains voltage?

    All caps have been replaced on the power supply board and have been installed correctly.

    I would start by verifying other voltages shown on the schematic, working back towards the transformer until you find the point where things start going wonky.

    What voltage are you getting at J807?

    Screen Shot 2018-06-09 at 7.24.54 PM.png
    Screen Shot 2018-06-09 at 7.17.28 PM.png
     
  3. willyrover

    willyrover Super Member

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  4. Marc1234

    Marc1234 New Member

    Messages:
    33
    J-807 79.7vdc j-806 59.9vdc creeps upward relay no longer engages at all :(
     
  5. Marc1234

    Marc1234 New Member

    Messages:
    33
    You also mentioned correct mains voltage not sure what that is referring to. I am pretty confident that all caps were installed correctly I marked each one and replaced one by one I did have a trace that was arched pretty bad on one of the bloated caps I just soldered to next component on same trace that should be no problem or am I wrong I included a picture. That’s the positive side of C-804 lead that is jumpered over to r-806 I believe
     

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  6. eiraved

    eiraved AK Subscriber Subscriber

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    Are you using a dim bulb tester (DBT)? Have you turned down the bias to minimum to see if the same thing occurs with bias at minimum? EDIT: Is R809 the bias?

    Welcome to AK!
     
    Last edited: Jun 9, 2018

     

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  7. Marc1234

    Marc1234 New Member

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    Thanks.! Yes r-809 on p-800 max counter clockwise. I can adj r-762 on both left and right channels on p-750 to “0” at speaker terminals not sure if that helps or complicates the matter any
     
  8. Marc1234

    Marc1234 New Member

    Messages:
    33
    No bulb tester but have a good dvm if need be I can make one are there any good links on here to follow to build one. From what I read yes to adj for 35vdc r-809
     
    Last edited: Jun 9, 2018
  9. willyrover

    willyrover Super Member

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    Mains voltage is the power coming from the wall socket. Are you sure the Marantz is set up for the correct wall voltage?

    We are not talking about bias. We are talking about the 35VDC regulated supply.

    59.9VDC at J807 is almost double what should be there (32.6VDC) and J807 is fed directly from a transformer secondary, through a pair of diodes and C801 filter cap.

    The 35VDC regulated section of the board that is adjusted using R809 is also fed from the same transformer secondary.

    Please verify that the your unit is set up for the correct wall voltage.

    Screen Shot 2018-06-09 at 8.38.15 PM.png
     
    Last edited: Jun 9, 2018
  10. eiraved

    eiraved AK Subscriber Subscriber

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  11. eiraved

    eiraved AK Subscriber Subscriber

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    Please post your location, are you in the US?
     

     

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  12. Marc1234

    Marc1234 New Member

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    U.S.A California To be exact where should I be checking for main in voltage is that in the transformer itself.?
     
  13. willyrover

    willyrover Super Member

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    6FC975E2-E0E7-481B-8A40-1F74EE8D1FF4.jpeg

    Terminal Block should be on back wall behind large filter caps. Jumpers should be set as follows.

    F96E9D93-AE60-44EC-9DAC-46E68FDE61A2.jpeg
     
    Last edited: Jun 9, 2018
  14. Marc1234

    Marc1234 New Member

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    Yea mine looks very different I see what you are referring to behind the the rear largest main 9000uf cap here’s some pics sorry it’s so dirty wanted to get it working first this is why I was asking if the main voltage change was to be made inside the transformer itself
     

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  15. eiraved

    eiraved AK Subscriber Subscriber

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    Seems like Willy has much knowledge on this amp so i'll defer to him on troubleshooting.
     
  16. willyrover

    willyrover Super Member

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    Not really. I'm about out of ideas. I don't know what would cause the OPs voltages to be so high straight off the rectifier. Hope the transformer itself isn’t bad.
     

     

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  17. willyrover

    willyrover Super Member

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    39EE8DF6-2690-4CAF-823F-7680E15483B6.jpeg
    So yours doesn’t have an input voltage selector. Hmmm...

    What is your AC voltage between J804 and J805?
     
  18. Marc1234

    Marc1234 New Member

    Messages:
    33
    Between j-804 and j-805 I get 95vac then meter climbs slowly turned off after 2 mins got to 103vac no relay click anymore either
     
  19. Marc1234

    Marc1234 New Member

    Messages:
    33
    I have taken more readings directly out of the transformer and the wires come out of the transformer to a relay or rectifier.? I included a picture the orange wires both show 62.3vac white at 0 and red at 185.5 also what is or does this green box do anyways
     

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  20. sregor

    sregor AK Subscriber Subscriber

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    IF I see it right, green box is diode bridge. HD05 - right next to transformer secondary in schematic.
    High voltages - you might take a second and test your meter - Get a fresh alkaline battery and see if it reads 1.6 volts. Many meters, with low batteries read all voltages too high. My 2 cents
     
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