left channel distortion

Discussion in 'Marantz Audio' started by Markojb, Aug 27, 2017.

  1. Markojb

    Markojb New Member

    Messages:
    11
    Yes, that where I always start :)
     

     

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  2. willyrover

    willyrover Super Member

    Messages:
    2,984
    Location:
    Hamilton
    2240: The main in/pre out jacks have internal contacts that uncouple the amp and preamp when an RCA plug is inserted. Try installing some RCA cables between the MAIN IN and PRE OUT jacks.


    (No idea why PRE OUT is labelled REMOTE on the schematic.)

    Screen Shot 2017-09-08 at 11.33.44 PM.png
     
    Last edited: Sep 8, 2017
  3. Markojb

    Markojb New Member

    Messages:
    11
    Hey Willy, tried that and get no soumd. In fact I am not getting any sound now where as a few weeks ago i was gettimg distorted sound. Plugging the ipod back into the main ins and all is well. I have no tried to replace the speaker relay in this unit.....should I as to rule this out?
     
  4. willyrover

    willyrover Super Member

    Messages:
    2,984
    Location:
    Hamilton
    If all is well with the iPod plugged in to the MAIN IN, then the relay is fine. The relay is AFTER the amplifier in the signal chain.

    We need to "divide and conquer". Between the AUX IN - there is either a switching problem or a TONE AMP board problem.

    JE01 and JE02 (one is left and one is right) on the tone board are fed off the volume control wiper. (JE03 is signal ground)

    We need to confirm that signal is getting from the AUX jack all the way through to JE01 and JE02. Easy with a scope. Without a scope, if you play a steady tone such as a 60hZ sine wave into the AUX input, and measure the AC voltage at this input - let's say it's 1 volt or so. You should be able to measure that same 1 volt at JE01 and JE02 with the volume all the way up.

    You should also see that 1 volt decrease as you lower the volume control.

    Do this with the unit powered OFF.
     
    Last edited: Sep 12, 2017
  5. Markojb

    Markojb New Member

    Messages:
    11
    Well I finally got around to working on this unit after a long break. I rebuilt the tone board putting in all new capacitors and transistors. All went well HOWEVER when doing the work on the tone board I inadvertently pulled off 2 wires that connect the board to the volume pot. I did not take a picture ( i usually do ) of this area as to where they go back as I i wasn't intending on removing so I took a fairly educated guess but when i went to hook back up I got no sound on the unit. Even with the volume cranked full I could even hear a hum or a hiss. Now, the problem could be that I put the wires back in the wrong spot OR the work i did did not repair what was wrong. To confirm, upon plugging my phone back in the main in she plays great and sound evens potentially better then it did.
    If any one has a picture of their 2240 upside down with the bottom cover off and I could zoom in on the volume pot that would help me. I stink at reading schematics as a quick look at the manual didn't help me much. Thanks again for your help guys!
    Mark
     
  6. rBuckner

    rBuckner Luv 2 Restore Subscriber

    Messages:
    9,553
    Location:
    Prescott, Arizona
    I may be getting a 2240 in for refurb very soon. PM me if you don't get this resolved in about a week or so.
     

     

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  7. Markojb

    Markojb New Member

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    11
    I appreciate that. Thanks
     

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