ACM-200 Double Ribbon--how to take it apart?

[Chris Long]

Hi Folks-
Trying to find out if anyone has taken the grill off an ACM-200 yet. I removed the 3 set screws 'round the bottom of the grill, but that just loosened the head from the rest of the body, and didn't help with the grill.

The microphone is fine; I just want to get a look at the ribbon assembly, for curiosity's sake. Thought I'd ask before I do any permanent damage...

Thanks!

 

[dgatwood]

You probably have to get into that top can somehow. No idea how, though. You might try removing the bottom can entirely and see if there are screws accessible from the underside of the top half.

 

[Chris Long]

Well, I took the plunge and got it done. Here are some observations, as well as some pictures to illustrate it.

To get it open, you need to remove the three screws around the base of the top half. At that point you can gently take the top half part of the way off--it's still connected to the bottom by wires, of course. By gently getting the wires to extend to their maximum length, you can see the underside of the ribbon motor/grill assembly. There are two tiny screws (picture #1, red arrow) holding the ribbon motor to the grill/basket; remove them and the ribbon motor can be slid out.

One of my ribbons was pretty loose and shaped like a roller coaster, so I decided to tighten it up. You have to peel back a metal mesh that is taped across the ribbons before you can get at them.

I removed the clamping plate at the bottom, gently scraped the ribbon off the armature (I used an Exacto knife). Fortunately the ribbon wasn't stuck to either part of the clamping assembly. I GENTLY took up the slack. I used a drop or two of denatured alcohol to hold the ribbon in place while I placed the clamping plate back on; checked the alignment, and tightened it down. Much better now.

I don't hear much of a difference--the microphone sounded fine before, but I feel better that I've taken the slack out of the ribbon.

Hope this helps others who might want to check out theirs, too. I highly recommend using the alcohol; it acts like a third hand, and dissipates with no harm done.