tele-tone: Speaker Cone Repair

Fellow Radiophiles,

Sometimes it is fun to put an unreasonable amount of effort into a repair.

One such case is the repair to the paper cone of the 4" speaker in this inexpensive American AC/DC set.

This cone had a hole covering almost one third of the area that was probable the result of rodent damage.

The speaker could have been easily replaced, but it was more fun to repair it.

The repair consisted in replacing the missing paper with paper from a common coffee filter. I stiffenned and glued the coffee filter paper with clear acrylic nail polish.

I rebuilt the inner section of the cone first, with a semicircle of coffee filter paper. I cut the paper to come up to the edge of the speaker "surround".

I applied this section to the back of the existing cone with acrylic nail polish and let it dry out.

Now I had an arc shaped gap where the surround still had to be rebuilt.

Then I cut a wider arc of coffee filter paper to overlap with the first section of coffee filter paper. The diameter of this arc must be significantly wider than the final diameter of the speaker to allow for the folds in the "surround".

I drew several arcs in the coffee filter arc to mark the location for the creases, and left about 1/4" overlap with the inner coffee filter rebuilt section.

I made the creases on the arc before applying the arc to the speaker with a sharp cylindrical edge that I rolled over a bed of soft paper.

After applying the coffee filter paper arc with acrylic nail polish, I let it dry and trimmed off the excess past the edge of the speaker.

The surround was gently worked in place while it was wet with the acrylic nail polish.

The overlap flap from the curround section was tucked under the central section of the rebuilt cone that was already dry and set in place.

I chose to leave the paper in white because I was very happy with the repair, and making the paper black was not otherwise justified in this case.

While I was stiffening the coffee filter paper I applied a low frequency to the speaker and listened for rattles. I had to trim some loose ends and make sure there were no gaps in the glue.

This set arrived with a lot of rust, but a sanding head on the mini drill cleared it up.

There was very little wrong with this set: a broken power switch and a few bad capacitors. I also added a 250mA MDL slow blow fuse at the power switch as an added measure of safety. The internal ground is AC-coupled to the chassis with 0.05uF. One unusual feature in this, otherwise very modest set, is the fully enclosed metal chassis with a metal bottom cover.

The grill is wide enough to show the speaker repair.

But the speaker is out of sight in normal use.

I bought this AM set while I was looking for the FM version, a Teletone model 1000. I was oriented in my search with help from our fellow radiophiles at www.antiqueradios.com.

Still looking for the FM version.

Regards,

-Joe

This article was edited 08.Feb.10 03:55 by Joe Sousa .

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