I thought I would post up my repairs of a 902 HF compression driver with a loose phase plug.
The culprit is the usual suspect, the tangerine phase plug notorious for losing it's adhesion.
To start, here are the things I used: 902 with loose phase plug, rubbing alcohol, lint free cloth, super glue gel, painters masking tape, and some thick printer paper.
First, I thoroughly clean the phase plug and the little "bowl" the plug sits in with rubbing alcohol. I use q-tip for the initial application of alcohol, but then switch over to a lint-free cloth to dry and polish everything. Then I use the painters tape to clean the voice coil gap and the phase plug to ensure they are all free of any debris.
Next, I put some of the super glue gel into a small plastic tray (used electronic parts packaging works great for this), and use a tiny flat-head screwdriver to apply the gel to phase plug. I'm very careful in the application of the gel to ensure that I don't get any unwanted gel into the phase slits on the plug itself, or near the edge of the plug that might find its way into the voice coil gap.
Once the glue gel is carefully applied to the phase plug, I press it into place in the driver, being very careful to get it centered on there before lowering it into place (again - I don't want glue in the gap or smearing into the slits). With that placement done, I place a strip of the thick paper into the voice coil gap to ensure that the plug is centered (kind of a shim), and that I don't get any glue in the gap.
The particular brand of super glue gel I'm using is a special formulation for gluing coral fragments in underwater applications. It is gooey, not runny, will hold things in place while the glue sets up. You can find super glue gel at the box stores too, but it's not quite as good as coral glue. Anyway, it sets up in about 1 minute and is cured in 5-10 minutes.
Remove the shim, put your diaphragm/vc back in, and you're back in business!
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