Yesterday i finally had it with this truck.
The rattling and scratching speaker in the drivers door annoyed me enough to get going with the repair. It also is pretty weak compared to the other speakers in the truck.
In the past months i gathered some experience with this kind of work and i racked up the equipment, tools and materials (read: leftovers from other repair jobs).
So here is a quick rundown on how i repaired a defective membrane on one of the rare speakers of my 1985 W250 “Mary”.
Removal from the door required pulling the doorcard which won’t be covered right now.
It’s simple: basic tools + brute force.
Fast forward through the disassembly and removal, here we have the problem on the table.
It is pretty obvious what caused the rattle and scratching noises.
The membrane had come off the metal cage by what seems to be fluid damage and force excerted from the plastic retainer the speaker is located in.
I began to disect the speaker and remove the gasket.
The gasket is the surround around the membrane made from cardboard.
Pretty obvious, huh?
I can repair that. The next step was to remove the membrane alltogether to try and flatten the distorted edge for re-glueing. It came off the cage easily and cutting and lifiting it from the paper cone was straightforward as well.
No problems whatsoever, the glue had lost all of its properties, was loose and could be peeled off.
To straighten the distorted edge of the membrane i used my electric iron, which worked surprisingly well and quick.
All flat again:
Getting ready for the glue-up.
And all slobbered up again. Sorry there is no pictures of the application of the glue but this stuff draws strands and tacks up quickly and i did not want to cover my phone with gluey fingerprints or stick a glove to it…
It looks a bit messy but that was done on purpose to reinforce the glue joint between the membrane and the cone. This will not hinder the “performance” of the speaker and is covered by the speaker covers.
I then hooked it up to my trusty old signal generator for aligning the cone and testing the speaker.
This particular signal generator is perfect for that task because of its output range of 3-30 volts. No problems could be heard any more.
Now why is this just part of the problem? Well, the speaker does not rattle and scratch anymore but it still is weak.
This might be a problem with the voice coil beeing damaged by the prolonged scratching but then again the connections might be wrong. I fiddled with these when i had to replace the original radio and there might be a phase error (swapped plus/minus) which leads to reduced output.
But that is a totally different story…
By the way, does anybody have the Chrysler AM/FM/Cassette radio, with a black face and part no. 4311 686 left over and would like to donate it to the project?
If it does not work, no problem, i can fix these. I just can’t find one…