Sega Blast City | Speaker Repair

First and foremost, this model was created by Lex Terieur who can be found in many arcade groups. He created a tutorial (in French) on the Neo-Arcadia forums and with his permission, I will share this STL and translate his instructions for easy access. Tutorial, STL, and images are all owned by Lex Terieur. Please note, on many occasions, Lex has informed folks that his model is not perfect and everyone should create their own. Finally, I did ask Lex for permission and will remove this post at any time if requested.

Like a good number of Sega Blast City units, the foam membranes of these oblong-shaped speakers are falling apart after more than 20 years of loyal service. Unfortunately, not having found a compatible speaker replacement, I started to manufacture my own surround, following the instructions found on this site.

It should be noted that the surround has a crucial role in preserving the linear movement of the cones during their vibrations. Any degradation of the surround can lead to misalignment that can destroy the coils, limiting any attempts at repair.

But the good news is that with light manipulation, this method should resurrect them.

This starts with the complete dismantling of the two speaker boxes (which requires the removal of the screen for greater ease) Ideally, you'll measure the surround,  inside and outside, in width and length.

Here comes the tricky part, which consists of making an original model with the right dimensions that can be used to mold new surrounds.

Start by gently scraping the old foam membrane and peeling off the plastic front.

Don't forget to remove the residue from under the cone and clean it with a little isopropyl alcohol.

And there you have it!!

Now we grab some woven compress (available in most pharmacies) that will serve as the structure of our new membrane.

Apply some glue on the PLA support which has been lightly sanded to remove the printing residues.

Place a large piece of compress on top of the previously glued support.

Apply gently with a brush to fit the shape without forming creases.

Then we apply a layer of liquid latex that we spread with a brush, in my case I added four coats, it's not an exact science.

Above all, wait until it completely dries before applying a new layer, the color will get much darker. On my end, I waited 24 hours between each coat. You have to be patient for good results.

When all the layers are complete, you can finally unmold your new surround. As you can see there is a bit of latex missing in the compress, a small layer on the back could remedy it, in my case, I did without it.

You can now cut out the excess, be mindful to leave 5mm in the center to stick on the underside of the cone.

I did a quick test fitting to make sure that everything was fine and I realized that I had to cut the edges on the sides.

And there you have it!!

Finally, the plastic front panels can be attached. It will be necessary to properly find where the screws will go. You do not want your screws to get caught in the surround at the risk of deforming it when tightening the speaker in the final phase.

Admit it, it's beautiful!

Next, we will use a liquid neoprene glue to attach the top of the cone, I used white glue to make it easier visually, it becomes transparent with drying.

The same is done on the inside of the membrane.

Normally, neoprene glue requires you to let it dry before putting it in place, but I wanted to be able to easily reposition the membrane when it is in place. Please note, that you have to crush it a little to set it properly. Therefore, I placed it immediately but waited 24 hours before bonding the other parts.

Additionally, I have nothing to apply pressure to this internal bond, although the shape of the cone will by itself press the membrane against it.

Please make sure that the membrane is centered at this stage.

As you can see, the glue will lose its white color as it dries. I've positioned these from recently glued on the left to the oldest glued on the right.

We continue by gluing the outer part of the surround with liquid neoprene glue.
 

You do not want to create a misalignment of the cone by pulling on the surround, this will kill the speakers prematurely. It is best to allow the membrane to settle on its own.
 

We can finally add weight to it and allow it to dry for 24 hours.

And there you have it!!

The results are very satisfying for such a cheap DIY solution.

Let's go for a test drive before we proceed to the next steps.

Finally, we reassemble the speaker box with some self-adhesive felt tape. This is not mandatory, but highly recommended.

Now we move on to the reassembly of the cabinet and the testing of games, first in Mono:

And now in test in Stereo:

Apologies, my phone doesn't do the bass rendering justice, but the comparison between the original and DIY surrounds is unparalleled. The repurposing of so many original parts will most likely provide us with an accurate representation of what these speakers sounded like when they were new.

Let's see if elevate my setup by adding a small subwoofer shortly.