"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:
    1,810
    Thanks for the guidance. I found these hollow end rivets on the McMaster-Carr website. Perhaps one of these may do the job. The HTML page uses a frame set so the link I provided won't take one directly to the page for hollow end rivets. (For folks searching for the rivets, click the link above and then click "rivets" and then look for "hollow-end rivets.")

    Here's a screen capture of their hollow-end rivet offerings. It looks like 3 diameters (9/64" 3/16" and 1/4") are offered. Hopefully, one of these fits the diameter McIntosh used.

    rivet2.jpg
     

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    Last edited: Jan 27, 2018

     

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  2. monkboughtlunch

    monkboughtlunch Super Member

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    1,810
    My tools are packed up at the moment. Would a basic pair of cutting pliers likely generate enough force to cut off the crimped end? Or would another tool be better suited for the task? I want to prevent damage to the plastic structure holding the rocker and rivet. See pic below.

    rocker1.jpg
     
  3. rollcentre

    rollcentre Boom-tizzz

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    Sure seems like a lot of trouble you're going thru. I think the only person that can answer that is you, Are your tools that hard to get to? A beefy pair that is "deflection resistant" when you are putting the "stank" on them may do the job, but remember, most cutters have the cutting edge offset a bit with an angle, it won't cut flush. And a beefy pair of cutters won't fit in a place where dinky ones will. I would find a better option. What's in your toolbox?
     
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  4. monkboughtlunch

    monkboughtlunch Super Member

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    1,810
    Due to moving, I don't have access to all my tools. Do you think a small dremel would be the best bet given the tight quarters?

    I agree it is a bit of trouble, but if there was already a "sticky" or "how to thread," it would be easy!

    The challenge is there is basically no publicly shared solution knowledge base -- so it comes down to trial and error and trying to find a suitable rivet and replacement foam.

    Without correcting the issue, the buttons feel either loose and wiggly or stuck. And foam dust is accumulating and sliding around behind the faceplate where it can eventually end up in in other places throughout the unit. Given the high quality of these vintage MAC pieces, I think it's worth it to try and find a solution to return the buttons to "like new" fluid performance.
     
    Last edited: Jan 27, 2018
  5. jlovda

    jlovda Things I loved from the 60's and 70's Subscriber

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    I just joined this forum. Hobby Lobby sells 8x10 dense foam sheets that about 2 mm thick. Easy to cut with scissors. You can get them plain or with a peel off adhesive backing. JoAnnes or Michaels may also have them too. They're cheap. This may solve your damping foam problem behind the rocker.
     
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  6. marantzfan

    marantzfan ... Subscriber

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    I wonder if these rods could simply be replaced with a small bolt and nut?

    There is a store that sells nothing but fasteners close to me... if I knew a size that works I could go take a look.
     
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  7. monkboughtlunch

    monkboughtlunch Super Member

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    1,810
    Another idea - does anyone here own either a 1990s C22 Frank H. McIntosh Commemorative Edition reissue or the newer 2009 60th Anniversary or 2015 C22 reissues (which are basically a reskinned C2300)?

    If so, please take off your faceplate and report back. I wonder if McIntosh still uses or at least still stocks the "rods" for more recent or new production C22 rocker switches.

    If that's the case, perhaps we could source new "rods" from the McIntosh parts dept that would fit the old 1960s rocker switches. In other words, do the reissue C22s use the same "rod" part and part size as the 1960s switches?

    Below: C22 reissues

    5543245208_ea2aba42b5_b.jpg

    1872820.jpg

    mcintoshc22angle.jpg
     
    Last edited: Jan 28, 2018
  8. rollcentre

    rollcentre Boom-tizzz

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    All I've been doing on mine is as soon as I remove the faceplate, I hook up a small attachment with a bristle end on to my shop vac and vacuum around those switches. It sucks up the foam dust and leaves the bare backing behind. I do this before I spray the switches and everything is dry, personally, I've never had a problem, but I've only had 4 or 5 of these types of units on my bench.

    As for the Dremel, I think that would work better. If you have the small cutoff wheel attachment, but you have to worry about the metal dust and abrasive grit from the wheel going everywhere, and id say that's worse than the foam dust.
     
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  9. rollcentre

    rollcentre Boom-tizzz

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    Location:
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    Fwiw also, MC used that foam in various places including faceplates and other places around the faceplate for blocking illumination from scattering behind dials etc. Whenever I see it I just immediately shop vac it off till it's gone, sometimes I have no choice to leave the adhesive backing (if stuck to a painted face plate) I use adhesive backed felt to replace it, and it works fantastic for me. If handled too much, It can sometimes a shed a stray strand of fiber, but nothing a bic lighter can't fix. I buy that stuff in sheets and trim pieces off of it, it amazing how much I've been through after servicing a few units.
     
  10. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,810
    I think I may have figured out the solution.

    I hunted around online for pictures of the rocker cover and mount so I can better understand how they are assembled. I finally found some pics of the plastic switch parts in an old auction.

    I made some notations on the parts photos with my observations (see pics below)

    Observation 1: The switch mount appears to simply plug in to the faceplate (see arrows I added pointing to the two plastic prongs). If that's the case, the rocker, switch mount and "rod" may simply unplug in one piece -- leaving the slider switch still in place and thus allowing access to both the slider and back of rocker for cleaning!

    Observation 2: I added a red line to the back of the rocker where I think the adhesive of new replacement foam needs to adhere. Since the back of the rocker is curved to "grip" the slider switch, simply stuffing in a new piece of foam without removing the rocker cover won't work since the adhesive needs to grip the back of the rocker's steeply sloping lines.

    Based on this, I think a potential solution for the infamous McIntosh foam rot issue may be:

    a) Pull out / unplug the rocker switch mounts (and the rod and rocker cover would come out with it in one piece)
    b) Clean back of rockers
    c) Clean front of slider switches left in place in the MX110
    d) Add new adhesive foam to back of removed rocker (see pic below)
    e) Plug switch mounts back in place (which contain the rod and rocker and new foam)

    If this is the solution, it means the rod (rivets) can stay in place (don't need to be cut out), and this may be a relatively easy procedure that virtually anyone can do at home and not have to risk shipping off to some technician to fix.

    If this is the "secret" to fix the rotted foam switches, it's odd that not a single McIntosh technician will share the solution publicly.

    Thoughts?

    Below: pics of switch mount and rocker cover with my notations.

    switchmount.jpg

    rockeradhesive.jpg
     
    Last edited: Jan 28, 2018
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  11. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,810
    In terms of finding the most suitable and durable replacement foam product, I reviewed the Frost King web site.

    I narrowed it down to these two products. Would one of these be suitable or is there a better product to use? If you visit the links below, scroll down on the product page to see the multiple sizes offered for each type of weatherstripping. I'm looking for a material that is resistant to rotting in the future.

    Rubber foam: https://www.frostking.com/products/weatherstripping/rubber-foam-weatherseal-5-year-guarantee

    077578012230.jpg

    Vinyl foam: https://www.frostking.com/products/weatherstripping/vinyl-foam-weatherseal-3-year-guarantee

    91GwQJfm9XL._SL1500_.jpg
     

     

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  12. Steve O

    Steve O Super Member

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    I think you’re going to encounter problems with both materials. Why? One side needs to have an adhesive film to adhere to the portion of the rocker you outlined in red in a previous post (see image below I “borrowed” from you) ... Both materials seem to have this. However.....pretty sure other side that actually contacts the slide switch protuberance needs to be a slick/tough film like Mylar so that it “slips” across the protuberance surface. The raw foam has a high coef of friction and I suspect it will bind w/o this film interface.

    FWIW, when I removed the foam residue from my rockers, a length of film came out of each one. I assume this is the film I note above.

    Curious to see how this all works out for you. I chose to accept a little slop in my switches since I couldn’t figure out how to replace the foam w/o also jeopardizing the switch itself. IOW, not worth the effort and hazard. YMMV


    [​IMG]
     
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  13. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,810
    Update. I tried tugging on the rocker switch mounts (see red arrows below for the part I'm referring to) to see if the mounts, rods and rocker covers will come out in one piece.

    Below: rocker switch mounts

    switchmountpull.jpg

    The switch mounts didn't seem like they were going to budge when pulled by hand. Since my small precision flathead screwdriver is packed up, I didn't have a decent tool to try to pry them out.

    I flipped the unit over to see if I could push the rocker switch mount tabs out from the inside.

    Below: is a view of the underside of the unit. I didn't see any access point that would allow pushing the rocker switch mount tabs outward.

    interior.jpg

    Below: here's an underside view of the rocker covers. The yellow is the dried remaining adhesive. Using tweezers I was able to get most of the mylar and adhesive backing out -- although some still remains. It's simply impossible to do a complete job when the rocker covers are still in place.

    underside1.jpg

    Below: this shows how much foam comes out after depressing the buttons just a few times. This is alarming as it reveals that a lot of foam dust could be roaming free behind your faceplate and could eventually work it's way into switches and potentiometers and wreak havoc.

    foamdrop.jpg
     
    Last edited: Jan 29, 2018
  14. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,810
    This is a great point. The below picture shows an example of what I pulled from behind just a single rocker switch cover.

    It's actually two different pieces of mylar-type material. One was possibly dry and the other was adhesive.

    I'm guessing the yellowish piece was adhesive and stuck to the rocker. The other darker piece may have touched the slider switch to reduce friction (but unclear if that piece of mylar was adhesive.)

    It's unclear if McIntosh used a single piece of foam with that Mylar on both sides -- or if there were two pieces of foam that had a single side of mylar on one side.

    Is there a weatherstripping product on the market today that has an adhesive mylar film side and a smooth mylar non-adhesive side sandwiching a single piece of foam?

    IMG_7212.jpg
     
    Last edited: Jan 29, 2018
  15. restorer-john

    restorer-john Addicted Member

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    The rocker switch metal mount tabs will be bent over to secure the slide switch and itself to the front chassis. Can't you get in behind and bend the tabs straight to remove the rocker switch mounts?

    Then you clean them anyway you like, drill out the rivets and replace, whatever. You could always run a brass pin right through the row of rockers to allow for easy repair down the track- just slide out the pin.
     
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  16. monkboughtlunch

    monkboughtlunch Super Member

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    1,810
    It seems like the rocker mount and tabs are plastic. Also - there doesn't appear to be a way to get in behind them. See pics below.

    Below: I think this rocker switch mount is plastic (but I don't have the unit handy at the moment to check).

    switchmount.jpg

    Below: Underside view. Didn't see a way to access the rocker mount tabs from underside

    interior-1.jpg
     

     

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  17. restorer-john

    restorer-john Addicted Member

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    I agree, the pic looks like there's not much room, but the rocker pins must go someplace. It looks all the world to me like black metal, I can't believe it would have survived if it were plastic and held on.

    You'll need someone with access to a unit to confirm.
     
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  18. jlovda

    jlovda Things I loved from the 60's and 70's Subscriber

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    I am quite sure these switches were permanently riveted together because they were never mean't to be disassembled after 50 years (just like woofer surrounds). I think the solution is to clean the back of the black plastic rockers as much as possible using pointed tweezers to remove old foam and plastic backing and stick two pieces of the window foam on the back of the black levers; one at the top and a symmetrical one at the bottom. The foam should be thick enough so that it just touches the chassis wall on the side where the rocker is out, maybe compressed a very tiny amount. One piece of foam will be compressed while the other is uncompressed but touching. Because the switch was permanently riveted, you will not be able to get into the "cavity" that surrounds the slide switch handle unless you disassemble like comment #56. You will not be able to completely remove all the free play but will only feel it when you are actually changing the switch position. I don't think you will ever get a slide switch to have the snap feel of a miniature bat handle switch. Slide switches never feel that way. You are just trying to get all the switches to line up evenly when they are in the same orientation (up or down). The JBL SA600 I once owned had metal bat handles glued to the handles of the slide switches with riveted pivot points but did not use any foam. The bat handle was up or down but had some free play that was determined by the slide switch itself. There are probably some tricks a professional restorer may share but he is not going to give away all his methods. That's how he makes a living.
     
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  19. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,810
    You were right. I checked and the mount and its tabs are metal! I didn't see a way from the inside underneath to push the metal tabs out.
     
  20. monkboughtlunch

    monkboughtlunch Super Member

    Messages:
    1,810
    After pulling out the mylar strips with tweezers I used a shop vac (per your recommendation) and vacuumed the rocker switches. This was a great recommendation on your part and I can confirm it removed the foam dust particles!

    After vacuuming, if I push the rocker switches, no more foam dust is falling out. It's a good feeling knowing there's no more foam debris floating around behind the faceplate where it could work it's way into switches / pots or behind dial glass.
     

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