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N_Cook N_Cook is offline
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Default Help! Crackling noise from speakers.

Matt Kissmann wrote in message

I'm hoping someone can help me! I have a Kenwood KR-9600 with a pair
of Pioneer speakers. Recently, there has been loud crackling and
hissing noises coming from my speakers (usually just one speaker).
This happens when there is no input and happens when each input is
selected with the selector knob. Any ideas? Suggestions for a fix?

Maybe useful, from my repair briefs

Kenwood KR 9600 monster tuner amp from 1978, 2 x 200 watt
Numerous problems due to corroded front panel
switches. Intermittent loss of channel,crackles
and loss of bass.
To access remove wooden case by removing allen
bolts from front and through case screws underneath.
To slide of lay front face down on a couple
of books and slide upwards.
Absolutely full of dust settling through top slots.
Crackly volume control removed and all switches.
Remove bottom steel cover.
To recondition vol pot remove final cover ,pull
off wiper disk. On levering 4 tags to release
next section beware of dedent ball near the 3
terminals. Ball mill in Dremmel to grind the
swages back on the end of the Ali shaft to remove
the dedent and wiper disk.
The switches have to be desoldered from the board
(cases not soldered to board) then prize away
tags to get to corroded sliders to recondition.
Mark the absence of any links that are absent
although silk screen printed as present.
Alps slide switches of that era had much stouter
thickness of the cases so would probably crack
the paxolin if forcibly prized off leaving the
static lines of contacts soldered to the pcb.
Used mole grips (lock -jaw pliers) fixed to
front anchor points on each switch
and desoldered each in tern with hot air gun .
Mark 1 to 6 and 2 way or 3 way.
One of the function panel lamps was out,not actually o/c.
Bad construction bulb wires soldered to copper wire
then touching pins (or maybe failed
"spot welds") that are soldered to the pcb,whole covered
in silicone rubber. Made proper solder joints
after pulling off silicone . Covered stem of bulb (where
it touches plastic surround) with PTFE tape. 50mA 7 to 8 Volt

Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on