Marantz 2325 Loud noise in both speakers HELP!

Discussion in 'Marantz Audio' started by johndoe10, Jan 17, 2018.

  1. johndoe10

    johndoe10 Active Member

    Messages:
    176
    Hi All -- I have a Marantz 2325 stereo receiver that I am trying to repair. There is a intermittent loud popping sound that emits from the speakers while in operation, but it doesn't happen in both speakers at the same time.

    All of the To-92 transistors have been replaced, along with the differential pairs in both channels on the driver boards, but the intermittent loud noise is still present. I also disconnected the RCA plug that connects the preamp section to the main amp, which should eliminate all components in the preamp as the culprit.

    Has any of you run into this same issue? If so, how was it remedied? Any help or advice in this matter would be greatly appreciated!

    Thanks -- John
     

     

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  2. wurlyman

    wurlyman Active Member

    Messages:
    254
    Location:
    Sacramento, CA
    What else have you done John? Have you re-capped any capacitors, Deoxit the switches and controls? How about the relay on the P800 power board. Can you hear the click within 5 seconds or so after you power on? Are any of the capacitors leaking or bulging? Give us more info please.
     
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  3. quaddriver

    quaddriver 120 What's per channel Subscriber

    dont have the scm in front of me, but find my thread about a cantankerous 2230 - different baby sister amp to be sure, but had the same problem and it was post differentials....it was either bias or VAS that had a bad to39, 139? something weird like that with a corroded leg - both sides!, replaced with some to126/to220 (I forget) modern stuff and it hushed right up
     
  4. johndoe10

    johndoe10 Active Member

    Messages:
    176
    Yes the relay clicks and all is well, then after a few minutes pass or sooner, the noise begins, then goes away. Sometimes it triggers the relay and sometimes it doesn't. The unit has never been recapped, but usually they are not the suspects in this situation.
    I'll will check for corroded leads on components like Quaddriver had mentioned first, then go from there.

    Thanks -- John
     
  5. johndoe10

    johndoe10 Active Member

    Messages:
    176
    Thanks for the tip. I will make a closer inspection of the component leads and see if I missed something. I'll keep you guys posted.

    Thanks -- John
     
  6. rBuckner

    rBuckner Luv 2 Restore Subscriber

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    On 2325's there is a buffer board on the bottom, the "H" board that I've had issues with in the past. I automatically replace all of those transistors when I rebuild these. There are also 4 double diodes that I don't trust and replace with two 1N4148 diodes in series. It would be great if you had an oscilloscope to monitor the inputs and outputs of this board, but I'm betting that's not the case.
     

     

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  7. johndoe10

    johndoe10 Active Member

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    Actually I do have one, it's a B&K dual trace. I'll try that next, and keep you posted as well.

    Thanks -- John
     
  8. johndoe10

    johndoe10 Active Member

    Messages:
    176
    Hi Guys -- Correct me if I am wrong here, but with the RCA plugs from the main amp boards and the jumpers from the back panel that connect the preamp to the main amp removed, this should narrow the problem down to the main amp boards only, right?

    Thanks -- John
     
  9. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    N. Richland Hills, TX
    The 2325 has internal jumpers, so to separate the Pre from Main, you would need to plug RCA’s into the Pre out and not plug the other end into the Main In. Then you could plug another Pre into the main in to see if it still had the problem.
     
  10. johndoe10

    johndoe10 Active Member

    Messages:
    176
    The 2325 also has RCA plugs that plug right into the main amp boards themselves on the bottom, I have those disconnected as well. That should narrow the problem down to the main amp boards only, right?

    Thanks -- John
     
  11. Robisme

    Robisme Sansui Enthusiast Subscriber

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    If in both channels I would look at the power supply. Perhaps monitor the power with a meter or scope and see how it looks when you get the pop.

    Rob
     

     

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  12. wurlyman

    wurlyman Active Member

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    The RCA's that plug into the amp boards come directly from the MAIN IN's on the back of the unit. If you plug RCA's into the PRE OUTs you've broken the signal from the internal jumpers AND the RCA's on the amp boards. To pull the board RCA's is redundant.
     
  13. johndoe10

    johndoe10 Active Member

    Messages:
    176
    The pop is happening in both channels, but not at the same time.
     
  14. johndoe10

    johndoe10 Active Member

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    176
    I don't have RCA's plugged into the Pre Outs. At the time it was just easier to unplug them from the amp boards.
     
  15. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    Location:
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    I think what Wurlyman is saying is that the simplest way to separate Pre from Main is plug an RCA into the Pre Out. But if you have it open and have access to the internal RCA, that should also separate the two. There just isn’t any advantage to doing it the way with the most difficult access from what I can see.
     
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  16. Leestereo

    Leestereo Super Member

    Messages:
    2,060
    Location:
    Ottawa, ON
    I suspect that the tantalum capacitor at C703 (33µF/6.3V) is failing; it can be replaced with a bipolar type (e.g., 33µF/25V Nichicon ES).
     

     

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  17. johndoe10

    johndoe10 Active Member

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    Am I able to replace it with a 33uf non-polar capacitor?

    Thanks -- John
     
  18. johndoe10

    johndoe10 Active Member

    Messages:
    176
    I left them unplugged after replacing the differential pairs and rest of the TO-92 transistors on the main amp boards. There was no reason to plug the RCA's back in since the problem exists within those boards.

    Thanks -- John
     
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  19. catrafter

    catrafter Marantz Specialist Subscriber

    Messages:
    6,126
    Location:
    Montana
    The input 'ground' and the output 'ground' on this (and many other) Marantz power amp modules are separate. If you don't have a 'ground' on the shield side of the input connector on the amp module the the power amp output will float or oscillate.

    Tom
     
  20. catrafter

    catrafter Marantz Specialist Subscriber

    Messages:
    6,126
    Location:
    Montana
    I don't know if this is your problem, but the large green resistors on the power amps (R719 and R720) can get so hot that after a long time their solder joints can crack.
    Sometimes this can even take out the 20V Zener diodes (H716 and H717).

    I always replace these resistors with 3W Metal Oxide types and make sure that I solder them properly.

    Tom
     

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