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donquixote99

AR-3a Midrange Grill Transplant

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The title gives the goal of this project. Here are three midranges:

A: post-175813-0-51150800-1433098924_thumb.

B: post-175813-0-49081500-1433098982_thumb.

C: post-175813-0-82120700-1433099051_thumb.

A is my uninjured midrange, B is the patient, a working midrange that came to me naked, as you see. C is a non-functional midrange that tests open, and is the donor. The hope is to make B look and sound like A.

The hard part here is getting the parts wanted off of C. They are glued down tight. Further, on the donor unit, the grill is inset from the outer flange. This is different from my OEM units, on which the whole face is flush, and is making things harder.

I'm willing to be destructive with the donor unit if necessary, but I'd rather not in case it's fault is actually repairable....

My idea at this point is to unscrew the four screws on the face of the donor. I expect this will enable me to pry-off the outer flange, the grill, and the damping, as a unit. X-acto chisel expected to be of use. I will then be able to cut around the inside of the flange with a utiltiy knife, removing the grill and damping.

Does this approach sound OK? Advice from anyone who's had these drivers apart very welcome. :)

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Take photos ... just guessing a heat gun may come in handy or some localized heat via solder gun :)

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Your advice is right-on, sir! But the disassembly is now done. It wasn't so bad. I'd found advice googling about epoxy that heat softens it, so I took a hair dryer to it, and was able to pry the grill out of it's recess without too much trouble.

I did try removing those screws, but flange showed no sign of moving easily. It's possibly glued to magnet, as well. That's when I started experimenting with heat, and got the grill out just prying around under it with a small screwdriver.

It wasn't a copious bead of epoxy I was dealing with, by the way, despite appearances. Now looks more like a circle of plastic tape. Grill probably set on with heat, the way I removed it. Pics taken, will post later.

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OK, here are the pics of the grill-removal from midrange operation. This donor is from an AR-3a, I was told, but not originally, I don't think. Per the pics in the Restoration Guide, it looks like the "Mk I," that was OEM on the AR-10pi or 11, AR p.n. 20010-1.

post-175813-0-46288800-1433186117_thumb. Grill Half-Off

Hair dryer and screwdriver are all you need.

You can see I desoldered the speaker leads from the lugs--did that because I thought I was going to take the whole front off, flange and all. This proved unnecessary. :)

post-175813-0-29082500-1433186152_thumb. Back of Grill

The sticky layer looks like black plastic tape, once you get into it. There's a layer of paper under that.

post-175813-0-78192900-1433186207_thumb. Midrange with Damping

The damping is just a disk of fiberglass, not made rigid or anything

post-175813-0-74511300-1433186241_thumb. Side view

Damping glued to speaker dome.

To be continued, but it's just a matter of cleaning bits up and gluing them together now. Main decision is what glue to use to glue the grill onto the working speaker. Candidates are epoxy, and Aliene's Tacky Glue. I'm leaning to Aliene's--don't think I need anything as heavy-duty as the epoxy.

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This sub-project finished!

post-175813-0-77144500-1433424546_thumb. Rubber cement used to attach damping disk.

post-175813-0-46650200-1433424600_thumb. After big chunks of old attaching-stuff picked-off, grill flange was flattened.

post-175813-0-79516100-1433424646_thumb. Finished product. Grill attached with Aleene's Tacky Glue.

Weighed flange down with circular pressure while glue curing (weight balanced on top of a roll of masking tape).

There will be more on the continuing process of restoring my Heathkit AS-103s, that i like to call 'DIY AR-3As.'

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This sub-project finished! ...There will be more on the continuing process of restoring my Heathkit AS-103s, that i like to call 'DIY AR-3As.'

Looks good. Start a thread on the 103's with pics so we can follow along :)

Roger

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