On Thu, 29 Oct 2015 09:44:38 -0400, Art Todesco
wrote:


There is almost always a way to open them. I'd bet, gently prying up the
grill will reveal some screws ... if indeed there are no other screws. I
once heard of an old film camera that had no screws. But, if you turned
the film wind know, which had a small hole in it, to a particular spot,
and looked into the hole, there was a screw behind the knob. That screw
opened the camera body.

I got it apart. The whole grill comes off. The cloth is attached to a
plastic frame and it all pops off. Under there are 4 screws, (plus that
obvious rear screw on the back). 5 screws total and it came apart.

As far as testing it. The wall module is marked 12VDC. It measures 15.5
volts, with or without the power switch turned on. That's pretty normal,
since a car's battery voltage is about the same. (I'm using an analog
VOM meter).

Placing the black lead on a known ground, I am seeing a voltage at
random places on the circuit board, such as resistor leads. There are
two IC chips on the board, one smaller one (Preamp), one larger one with
a heat sink, (Audio Output). The heat sink gets warm if the power is
left turned on for awhile. Of course I have no schematic so I cant
actually do any actual testing, and ICs are generally near impossible to
find replacements for.

Other tests: The input cord has a resistance on both L & R channels to
the tip of the cord (with my meter on 1K ohm scale). So that tells me
the cord is ok. The actual speaker inside of the case clicks when I
touch my test leads to the terminals (with circuit board wires unplugged
from it). That indicates the actual speaker is ok.

There are no visual bad parts such as a charred part(s) or bulging
capacitors, and from what I can see on that tiny board, there are no
loose solder joints or cracks in the board.

This pretty much tells me that the amplifier circuit (board) is bad.
Probably one of the chips failed. I'm not sure why the output chip heat
sink is getting warm with no sound coming out of it. That may be the
failed part, or maybe the preamp chip????? Either way, I now know it's
the board itself, and without a schematic and all sorts of testing
devices, it's not really possible to test any further. (Nor worth my
time).

I'll have to go on craigslist and find some new speakers.

I'm going to save the actual speakers from these. They may come in handy
for some other use.

It's kind of weird how this speaker was working fine the last time I
used it. I turned it off, and when I turned it on, it was dead. Nothing
was disturbed. But I suppose some part died, either a IC chip or
capacitor (most likely).