1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

"Loose" McIntosh black rocker switches: can these be tightened or retensioned?

Discussion in 'McIntosh Audio' started by monkboughtlunch, May 6, 2017.

  1. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    How does the replacement foam material feel? Do all the switches feel smooth and fluid now? If you happen to take off your faceplate to change dial lighting for LEDs, would you be happy to post some images of your replacement foam behind the rockers? I'm curious if it is single sided or double-sided mylar and if one piece was inserted from top to bottom -- or if there are two separate pieces (i.e. one pushed up from bottom and one pushed down from top).
     

     

    Please register to disable this ad.

  2. TR6man98

    TR6man98 Well-Known Member

    Messages:
    739
    Location:
    Seattle, WA
    Have you tried to call Audio classic and order new switches? You could also ask for advice.
    Looking at your pic. 1 (post #53) I see no way switch would be riveted to chassis.
    More like silver base of each switch tabs into the slots in the face plate.
    Pic 2 shows some bent end tabs holding the board with wire connections
    Hard to see but could that be what holds switch to the chassis?
    Good luck
     
    monkboughtlunch likes this.
  3. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    Thanks. After studying this issue, I think there are three unique solutions to the foam rot issue:

    a) Pull mylar out with tweezers and shop vac the foam dust out. Live with the loose, wobbly rocker switches
    b) Try and stuff new foam in the top and bottom of rocker opening (without removing the rocker cover)
    c) Cut the crimped ends off the rivet bars holding the rockers in place. Pull out the rivet bars. Remove the rocker covers. Then clean back of rocker covers and front of slider switches. Apply new foam to back of rocker. Then replace rockers and install new replacement rivet bars.

    Option "C" is the most involved, but should restore the unit to original "like new" switch performance. The challenge is that option "C" requires sourcing a suitable cutting instrument as well replacement rivet bars and adhesive foam with mylar protective sheaths sandwiching the foam.
     
    Last edited: Jan 30, 2018
  4. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    Do you think this material might work?

    https://www.tmhardware.com/Weatherstripping-Tape-Mylar-Backed-Self-Adhesive-Vinyl-Camper-Tape.html

    Weatherstripping Tape, Mylar Backed Self-Adhesive Sponge Vinyl Camper Tape, 30 Ft. Roll

    This Self-Adhesive Weatherstripping / Camper Tape is made of high quality Mylar Backed Closed Cell Sponge Vinyl. It is specifically designed to be applied as a seal between a camper and truck bed. Can also be used as a general Mylar backed weatherstrip where Mylar backing is desired, such as for door jamb and header sealing.

    Dimensions: Tape measures 1-1/4" Wide x 3/16" Thick and comes in rolls of 30' Length.

    Installation: Self-Adhesive Backing ensures simple, hassle free installation.
    • Closed Cell Sponge Vinyl Material
    • Mylar Backing
    • Self-Adhesive Backing for Easy Application
    • Designed to Seal Camper and Truck Bed
    • Sold in Rolls of 30'
    480.jpg

    RollTape_Wide_(LR).jpg
     
    Last edited: Feb 1, 2018
  5. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    The hinge rods that allow the rocker covers to rotate appear to be hollow end rivets. It appears as though McIntosh cut the tail end of the rivet with a dremel half way. This allows for easy crimping to lock it in place.

    I'm thinking the crimped ends could be cut off with a dremel and a new hollow end rivet could be used to replace the original.

    rocker.jpg
     
    Last edited: Feb 1, 2018
  6. Steve O

    Steve O Super Member

    Messages:
    1,167
    Location:
    SE MI
    It might. However............from dimensions noted, if you try to use this stuff you’re going to be doing a lot of trimming.
     
    monkboughtlunch likes this.

     

    Please register to disable this ad.

  7. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    I measured the hollow rivets with a caliper (per below photo) and they appear to be 3/32" in diameter. It appears the length McIntosh used is approximately 1" for the two rivets holding two rockers and 1/2" for the two rivets holding one rocker. (There are six total rockers on the MX110).

    However, I'm not seeing any hollow 3/32" diameter hollow rivets in in either 1" or 1/2" lengths when I search online.

    I wonder If there could be a better a approach. Instead of using four rivets, is there a solution in which there are only two fastener rods, each holding three rockers? If so, each of the two rods would need to be at least 1.5" long. Since there is empty space on either side of each three-rocker array on the MX110, the fastener rod could be longer than 1.5" long (no obstructions).

    Thoughts on any fasteners that are this long or slightly longer? And is there a fastener that would not need to be crimped? Perhaps one end could plug in or screw in to lock in place and allow it to be reused if foam goes bad again in the future?

    IMG_7618.jpg
     
    Last edited: Feb 15, 2018
  8. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    Progress update. Nearly complete. If you have a C22, MX110, C11, MA230 or MA5100 with loose and/or scarred rocker covers, this solution may interest you.

    I originally planned to make this repair given the loose, sloppy feel of the rocker buttons and rotted foam. I took the opportunity to install new rocker covers as the old ones were scarred with scratches and fingernail indentions. You could just as easily keep your original rocker covers if you are happy with them.

    Tools used:
    • Oscillating multi-tool with metal cutting blade (e.g. Dremel MM40-05 Multi-Max).
    • Scissors or exacto knife
    • Shop vac
    Parts:
    • K&S Precision Metals #9820 2mm brass tube
    • New McIntosh C22 reissue rocker covers #07159700
    • Pemko Camper Tape PEM-P480 (mylar backed closed cell vinyl sponge tape, waterproof)
    • 99% isopropyl alcohol
    • Cotton swabs
    • Rubber Cement
    Steps:
    • Use an oscillating multi-tool to drill through the solid rivets, which have hollow crimped ends.
    • Vacuum metal debris
    • Use 99% isopropyl alcohol to remove glue and foam from the slider switches (and old rocker covers if you reuse them)
    • Cut foam to size and adhere with rubber cement (or a superior adhesive) to back of rocker covers
    • Cut 2mm brass tube to size. You will need to cut four pieces total because the potentiometers make it impossible to thread two long pieces of tubing. Instead you need one medium and one short length of tubing per side -- totaling four pieces.
    • Install new rocker covers and insert 2mm brass tubing
    • Crimp ends of brass tubes
    Below: multi-tool cutting rivets to extract the old rocker covers

    IMG_7870.jpg

    Below: The elusive slider switches finally revealed.

    IMG_7872.jpg

    Below: Vacuuming debris

    IMG_7880.jpg

    Below: The old tired, scarred rocker covers

    IMG_7878.jpg

    Below: New C22 rocker cover sitting on top of extracted 1960s MX110 rocker cover for comparison. New cover appears to be virtually identical to vintage.

    IMG_7898.jpg

    Below: testing the fit of K&S 2mm brass tube through the pivot hole of brand new rocker cover.

    IMG_7768.jpg

    Below: Experimenting with the Pemko P480 camper tape using an old rocker cover in order to match the old glue marks for sizing. This tape has an adhesive side which faces the back of the rocker cover. In addition, the tape has a mylar protective coating which faces the slider switch. I discovered that adhesive on the Pemko facing the rocker cover will need to be supplemented. I'm thinking rubber cement may work but I haven't yet tested it. You can tell from the yellow gunk on the old rocker covers that McIntosh also had to use some type of extra glue material to lock down the foam.

    IMG_7907.jpg

    Below: clean debris off of the slider switches.

    IMG_7893.jpg

    Below: Confirming the brand new C22 rocker cover will fit with the 2mm K&S brass tube. The new rocker cover is fresh and unscarred by decades of fingernail indentions!

    newcover.jpg

    Next steps: I need to find a suitable adhesive to bind foam and plastic. Would rubber cement be best?

    After I have the new foam firmly secured, I will install the new covers, crimp the tubing and button it back up.
     
    Last edited: Mar 13, 2018
    KentTeffeteller and psychoaudio like this.
  9. Snappahead

    Snappahead AK Subscriber Subscriber

    Messages:
    244
    It looks like there's enough "meat" on the end of the rivet where you could crimp it back enough to slide the rivet out. Then crimp it back when you're done. Tedious but not impossible.
     
  10. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    I looked closely and it was virtually impossible to round the crimped ends and reuse. Much easier to get a new 2mm brass tube. See post #68.
     
  11. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,813
    One thing I noticed after the rockers were removed is that each of the six slider switches has a different level of resistance. I'm assuming that is not normal. I'm guessing they should all slide with similar resistance when brand new. Do I need to hit those sliders with a spray of faderlube (accessing from under the chassis) to add some lube and deox?
     

     

    Please register to disable this ad.

Share This Page