Marantz 22xx knob "alignment"

Discussion in 'Marantz Audio' started by Rococo, Aug 20, 2017.

  1. Rococo

    Rococo New Member

    Messages:
    39
    Evening all,

    Please excuse this rambling question as I'm trying to suss out how to word what it is in trying to ask...

    I have a 2238b which works great in all ways, no issues with sound or function.

    When i received and completed the initial cleaning of this unit i noticed that the bass, mid, and treble knobs were not "centered" properly. By this i mean that if you are looking at my basd knob as a clock and the 12 is supposed to be neutral, in actuality its more like 3. If i were to try and then the bass knob from 12 to 4 or 5 it will only go to 3. ( is this making sense)

    The same is seen with the other knobs except for selector and volume but to varying degrees.

    Anyone else seen this and is there an easy fix? Last time i had the faceplate of it did not seem to be an easy way to change the "balance" to reflect the true reading but I've probably overlooked something obvious.

    I've included a picture of my treble turned up all the way. If i try and turn it all the way down it will come back around the dial counter clockwise to the 5.
     

    Attached Files:

    Last edited: Aug 20, 2017
  2. Steven Tate

    Steven Tate AK Subscriber Subscriber

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    If I'm understanding the problem, looks like you just need to reposition the knobs. They pull straight off and can be turned and repositioned before pushing them back on. For example, remove the bass knob, turn pot to what seems like center, and replace knob with pointer at 12 o'clock. These are dual pots, so there will be an inner and outer knob for each control.
     
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  3. Rococo

    Rococo New Member

    Messages:
    39
    Thanks, i understand what you mean. i guess a better way to explain as well would be that the pot itself is also exhibiting the same behavior. If i left the knob off and just turned the pot it would also turn far more in one direction than another. I did check what you are recommending when originally cleaning but am going to do so again.
     
  4. bluestime

    bluestime AK Subscriber Subscriber

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    Skagit Valley, Wa.
    Do the shafts have a flat side or are they splined? If they have flat sides, they may be the wrong knobs.
     
  5. wurlyman

    wurlyman Active Member

    Messages:
    121
    Location:
    Sacramento, CA
    You're right Steven but I found it easier to first turn the knob fully counter clockwise then remove the knobs and push them back on lining the marker up with the first dot on the left on the face plate. You get that one correct and the others will all line up.
     
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  6. jd3rdcoast

    jd3rdcoast New Member

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    Location:
    Houston Area
    Might also pull knobs and check to see if the pots are secured to faceplate with a keep nut. If the post are not soldered to a board it could be possible they rotated on the faceplate. In that case the movement of pot would be further counterclockwise than the normal 7:00 stopping point. (check that first). You would then need to loosen the nut and rotate the pot back to it's normal position and retighten. Then check knob alignment and adjust as indicated.
     
  7. runningdog

    runningdog AK Subscriber Subscriber

    Messages:
    299
    Location:
    Sonoma, CA
    The 'fluted' finish knobs were made with the shaft flat in 2 different locations relative to the marker on the knob. They are about 90 degrees off from each other. The wrong set will produce the results you are seeing. Have you (or someone else) replaced the bass/mid/treble knobs?

    fluted knobs different flats.jpg
     
  8. SaturationPt

    SaturationPt AK Subscriber Subscriber

    Messages:
    586
    Location:
    N.E. Indiana
    My Marantz 2285 & 2325 receivers' knobs are an aluminum shell glued to a plastic inner, if the glue has come loose the aluminum will slip on the plastic inside.
     
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  9. Rococo

    Rococo New Member

    Messages:
    39
    This is it! I was convinced that the actual pots were turning too far in one direction or another but ive found that its just one.

    One is already a little loose. I just need to find a way to loosen the inner plastic again to allow them to be turned to the proper angle with breaking them.

    Thank you.
     
  10. SaturationPt

    SaturationPt AK Subscriber Subscriber

    Messages:
    586
    Location:
    N.E. Indiana
    Pull them off, the aluminum will slide off of the plastic if it's already loose (and sometimes if it isn't, time has a way of releasing that bond). It's step one of cleaning the faceplate anyway, remove knobs and remove faceplate ...
     
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  11. catrafter

    catrafter Marantz Specialist Subscriber

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    Location:
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    You can break the glue bond between the aluminum sleeve and the inner plastic part of Marantz knobs by running them through an ultrasonic cleaner several times.

    Tom
     
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  12. jjerm80

    jjerm80 New Member

    Messages:
    16
    Location:
    Philadelphia
    Not to hijack this thread, but on a similar issue...how can I confirm the balance knob on my 2245 is truly centered? It seems the knob can slide off and on the post at any point it wants. How I can assure I've got it dead centered? Thanks!
     
  13. wurlyman

    wurlyman Active Member

    Messages:
    121
    Location:
    Sacramento, CA
    Doesn't the knob grip the post tightly? If it does, you can check for center by turning fully to the left and checking to see that the indicator line lines up with the dot on the faceplate. If it doesn't, remove the knob with two teaspoons and replace it so that it does. If it doesn't fit tightly, remove the knob and VERY CAREFULLY use a flat blade screwdriver to spread the slot in the end of the shaft a little. Then put the knob back on as I described before. Hope that helps.
     
  14. catrafter

    catrafter Marantz Specialist Subscriber

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    Location:
    Montana
    You can use your ears, providing you don't have any major hearing issues..
    Press the mono button, sit between the two speakers and adjust the balance until the volume level sounds the same.

    There are other more sophisticated methods.

    Tom
     
  15. jjerm80

    jjerm80 New Member

    Messages:
    16
    Location:
    Philadelphia
    Thanks, Tom. This is the method I went for, and I think I'm in a pretty good place. That said, when you say more "sophisticated" methods, how sophisticated are talking?
     
  16. catrafter

    catrafter Marantz Specialist Subscriber

    Messages:
    5,791
    Location:
    Montana
    By sophisticated I mean things like audio signal generators and calibrated AC voltmeters.
    You can feed a signal, say 1kHz, into both aux inputs while you monitor the pre-amp outs and/or the speaker outputs (properly loaded, of course). The levels should be with in about 1dB of each other when the balance control is in the center of it's travel for just about any position of the volume control above fully CCW.

    Tom
     
  17. jjerm80

    jjerm80 New Member

    Messages:
    16
    Location:
    Philadelphia
    Thank you, Tom. All of that is just above my pay grade, but I appreciate you taking the time to explain the process.
     
  18. restorer-john

    restorer-john Super Member

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    3,826
    Location:
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    The easiest and most extremely accurate no-equipment-required way to balance, is to hit the mono button and lift the two negative speaker wires at the amp/receiver. Connect them together, leaving the positives in place.

    Play some music at the level you normally have the volume control and adjust the balance to completely null out the sound. The balance is then perfect. What you are essentially doing is nulling out the difference in level between the two channels.

    note: only to be used on common ground, non-BTL amps
     
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  19. jjerm80

    jjerm80 New Member

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    16
    Location:
    Philadelphia
    this sounds like an interesting approach. so, to be clear, I would unplug the negative speaker wires from the back of the amp and twist the two wires together (but not plug them back into the amp). everything else would stay untouched?
     
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  20. restorer-john

    restorer-john Super Member

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    3,826
    Location:
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    Yes, that is correct. Float the twisted negatives in space.

    Press the mono button. This is important. Otherwise you will merely hear all the difference information in the stereo recording. That, in itself can be interesting and is the basis of the 'rear presence' speakers often used in the 1970s on receivers and systems to simulate a 'surround' effect.

    The null is a very useful way to determine volume tracking and any phase differences between amplifier channels. Ideally, dead silence is your goal at all volume settings, but volume pots simply don't track well enough for that. Pick your normal listening level position on the volume pot and balance it at that point perfectly. I always use this method in my own system.

    Again, only to be used on common ground, not BTL (bridged, tied load) amps.
     
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