Sony Dream Machine clock radio

0) Read the last answer first :) it is the most likely.

1) Make sure that the noise is electronic, not mechanical,

a) Electronic noise comes from the speaker

b) Mechanical nose originates in the clock
(older mechanical clocks only)

c) Clocks come in 3 varieties:
Electronic
Mechanical "Flip Leaf"
Mechanical "Motor/ Gear" driven.

2) Assuming that your clock is electronic, there are
only two possibilities for causing static.

a) Extremely intense electromagnetic interference,
as in radio waves, from a thunderstorm or a powerful
transmitter nearby, such as a HAM radio or even
an active cell phone.

Intense electro-magnetic waves can be picked up by
internal wires within the radio which act as an antenna,
rectified (demodulated) by internal diodes and transistors,
filtered by internal capacitors and the speaker's inertia,
and still present enough audio frequency energy to the
sensitive speaker coil to be "quite" audible and irritating.

This can happen even with the power off, when the
interference is so strong that it needs no amplification !

This happens to my computer speakers, every time my
cell phone rings, and starts transmitting a return signal.


3) The power switch is intermittently shorting causing a small
amount of DC power to enter the radio, the more intermittent
the switch, the more noisy it gets.

This causes my old clock radio to turn on by itself when its
not supposed to.

The cause of the problem in either in the main power/ mode
switch, or in the clock driven switch or relay.

4) Old switches and volume controls get oxidized with time
and/or bridged by products of corrosion. The simple solution
is to clean them using a good aerosol contact cleaner,
available from an electronic shop for about 10 bucks.

Simply spray the cleaner into all the switches and controls,
while vigorously exercising each switch or control back and forth.

Make sure that you use a safe "electronic cleaner" designed
for the job. It must be safe on plastics, non-conductive, good
solvent and it must evaporate quickly. Don't breath the stuff !!!

Typically the spray will contain TF (tri-fluoro-ethane), or some
other freon substitute.

Freon (Di-fluoro-di-chloro methane) is bad for the ionosphere,
now illegal in most countries for that reason.

Also stay away from Carbon-Tetra-Chloride, which is
VERY toxic.

Do NOT improvise, or use acetone or alcohols, which may (will)
melt the plastic, causing the controls to permanently seize.

Get electronic contact cleaner from an electronics hobby shop.

Good luck. Martin
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