Meridian tweeter repair

Meridian tweeter ferrofluid replacement
Details about symptoms here
https://www.meridianunplugged.com/ubb...

And images of process here
https://www.meridianunplugged.com/ubb...

Equipment Required.

1 pack APG L11 900microlitres
available here for the UK
https://www.eBay.co.uk/str/billynomat...
and here for the US
https://www.parts-express.com/Ferro.....

several strips of blotting paper or filter paper
70% isopropyl alcohol
Small jewelers screwdrivers
cotton buds
wooden kebab sticks cut to 3 inch lengths approx or matchsticks of the right dimensions.
torx screwdriver
small syringe
superglue

Method

Be aware that any metallic objects such as screwdrivers and screws will be attracted towards the magnet and as such care needs to be taken to avoid damage to the dome. Ensure the area is clean. Ferrofluid is an irritant, if you get any on your hands wash it off immediately.

Insert a small screwdriver through one of the holes near to the edge of the grill and lever against the surface of the tweeter plastic just enough to lift up the edge of the grill in order that you can insert a slightly larger screwdriver under the edge, now remove the first screwdriver and work around the edge of the grill easing it off as you go.

Remove the 4 torx screws holding the tweeter together and set them off well to the side away from the magnet. Note the orientation of the terminals relative to the label and if you can mark both sides to ensue it goes back together the same way.
Separate the plastic assembly from the magnet, if there is resistance use one of the small screwdrivers at the interface between the two halves to loosen them. Place the voice coil assembly dome side down on a flat surface.

I opted to clean the old ferrofluid from the voice-coil with a cotton bud soaked in IPA however these parts are extremely delicate and easy to deform so it may be that this step was unnecessary. If you are at all unsure then I would omit this step. I did the H1054 tweeter first and found that the H539 voice-coil seemed way more delicate.

Insert a strip of blotting paper into the magnet gap and run it around to soak up as much old ferrofluid as possible, repeat this step five or six times until the strips are almost clean when they come out.

Place a very small amount of IPA into the magnet gap being careful not to spill or overfill and leave this for a minute.

Now repeat the steps with the blotting paper until they come out clean and dry. Set aside of 5 minutes to dry out.

Fill the gap with ferrofluid to about 75% or until you can just see it, the ferrofluid should run into the gap without having to squeeze it much, if you overfill the gap use blotting paper in the gap to remove some. There was enough ferrofluid to do around 3 tweeters.

Screw two of the wooden dowels or matchsticks into two of the screw holes in the magnet assembly, they should be a reasonably tight fit as if they are too loose they may result in misalignment of the voice-coil with the gap resulting in potential damage to the voice coil.

Align the voice-coil assembly with the wooden guides ensuring the orientation is the same as when it was taken apart and ease the two halves of the tweeter together. On my two tweeters there was a tab on the magnet gasket at the same side as the terminals.

Fit the torx screws.

Use superglue to refit the grill.

Test the tweeter. I used a mono signal to my speakers and used the balance on the remote to compare the refurbished tweeter to the undamaged one on the other speaker and could tell no difference in performance between the H1054 that was repaired and the original in the other speaker so absolutely a success there.
I adjusted the tweeter output on the donor speaker and fitted the H539 and performed the same tests and although the tweeter had improved from before it was still slightly muted at high frequencies so I would not use this tweeter.