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MX 110: replacing magic eye tube

Discussion in 'McIntosh Audio' started by monkboughtlunch, Jan 26, 2018.

  1. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,796
    Has anyone here replaced the magic eye tube on an MX110?

    I was able to replace the FM stereo lamp (despite the cramped area).

    Now I want to replace the magic eye tuning tube (mine is original and faded). It looks like replacing this tube will be a greater challenge given it's size and that it is in extremely cramped quarters.

    Does anyone have any recommendations on the best approach to replace the magic eye tube?
     

     

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  2. rollcentre

    rollcentre Boom-tizzz

    Messages:
    526
    Location:
    DFW,TX, United States
    I replaced mine a week or so back. I removed the top panel, to do that you take the side caps off that have the red trimpots behind it, there are 2 small screws on each side to remove there, and the two visible screws on the sides of the top panel. Once you have that off you can see the tube. I pulled the socket off the tube a moved it aside and removed the old tube and slid in the new one and hooked back up the socket. There is plenty of room to do it without disturbing the dial cord. Power on the unit and check the alignment of the tube. You'll probably need to vacuum out the unit after you do this because the piece of foam that surrounds the tube turns into dust if you touch it, and that's pretty much impossible not to do.


    The new tube is beautiful and bright. Mine was Philco branded, but has a diamond on the bottom, I'm thinking it's actually Telefunken because of that.



    IMG_20180106_212903.jpg
     
    Last edited: Jan 26, 2018
  3. dshoaf

    dshoaf That high voltage buzz

    Messages:
    10,107
    Location:
    Santa Cruz, CA
    I've got a couple of spares but have not found any reason to change one out yet. The biggest problem will be getting to it and then _gently_ removing the base connection off of the pins.

    Cheers,

    David
     
  4. 62caddy

    62caddy Trust but verify Subscriber

    Messages:
    9,135
    Location:
    NEPA
    Ryan just replaced mine last week when it finally gave up. The new tube is much brighter.
     
  5. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,796
    Here are some pics of my MX110 magic eye tube change out for posterity. I couldn't find any info online about this process, so maybe this "how to" pictorial will be helpful to folks tackling this in the future.

    The foam had disintegrated and was everywhere. I vacuumed it out and installed weather stripping before installing the new tube. It's a good idea to get this rotting foam out of there as it could wreak havoc if it gets into pots and switches.

    Tip: After examining the cramped space, I realized if I removed the tube bracket with the tube still inside of it, then the tube removal/replacement, clean up of rotted foam and installation of weather stripping would be a lot easier. To remove the tube bracket, you have to unscrew the left metal clamp holding the dial glass in place. Behind that clamp you will find a screw to untether the tube bracket. Simply remove the bracket with the tube still nestled inside it.

    Steps:

    Turn unit off. Remove inspection cover, faceplate and dial glass.

    Below: I noted with a red arrow below the screw behind the dial glass clamp to release the tube bracket.

    IMG_7289.jpg

    Below: Original EM87 eye tube and rotted, crumbling foam. There is no more foam cushioning left to keep a gap between the clamp and metal backsplash. The original tube was marked "Made in Germany."

    foamrot2.jpg

    Wiggle the socket off the tube. With the aforementioned faceplate screw removed -- pull out the tube bracket with the tube still clamped inside the bracket.

    Below: This image shows the removed bracket with new tube installed. It's much easier to pull out the old tube and insert the new one with the bracket removed due to the extremely tight space in the MX110.

    IMG_7298.jpg

    Below: Old tube on left. New tube on right. You can find new old stock made in Germany EM87 tubes for cheap. This one was branded Zenith but was made in Germany. Note the silvered discolorations on old tube. 1960s era German EM87 tubes are high quality.

    IMG_7286.jpg

    Below: Wipe grime and foam off the back of the steel blue tube gel filter using a damp microfiber cloth.

    IMG_7296.jpg

    Below:
    After vacuuming rotted foam out and scraping old foam adhesive away, apply weather stripping. Again, having the tube bracket removed makes the application of the weatherstripping a snap.

    IMG_7302.jpg

    Below: Reinstall tube bracket with new tube inside and reattach the socket. Power unit back up to test.

    IMG_7305.jpg

    Below: Make sure tube is centered. You will need to center the tube via trial and error. Remember to power unit off before moving the tube by hand. When satisfied tube is centered, button unit back up.

    IMG_7347.jpg
     
    Last edited: Feb 17, 2018
    txturbo, 62caddy and AlTinkster92 like this.
  6. mnmmt

    mnmmt AK Subscriber Subscriber

    Messages:
    133
    Location:
    Minnesota
    Nice! Thanks for the photos!
     

     

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  7. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

    Messages:
    3,196
    Location:
    NC
    Great thread and many thanks! AL
     

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