Linn LK85 Service Manual page 11

nd
2 June 1999
Amplifier & Audio Problems
The following are some problems you may encounter with the audio output of theLK85 or LK140.
It is assumed at this point that it is definitely the LK85 or LK140 that is causing the problem and you have
ruled out all other aspects of the system. If you have not – please do so before proceeding.
Amplifier & Audio problems
Symptom Circumstances
No output from Probably constant.
one or both Ensure, however,
channels. that the amp is not
May be tripped and is not in
accompanied by Standby (See
a popping or and
buzzing noise. sections above)
Clicking, buzzing May be intermittent,
or popping noise but probably
at output of both constant
channels.
Output is mono, May be intermittent,
not stereo – even but probably
if balance is constant
adjusted on pre-
amp, output of
both channels of
power amp
remain equal.
Thumping/ May be intermittent,
banging noise but probably
through speakers constant
when switching
between inputs of
pre-amp
DC at the output
Symptom Circumstances
DC (around 2V) Only happens when
at the output of unit is not
both channels. connected to
speakers and/or
pre-amp.
DC voltage at the Probably constant
output of one or
both channels
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Contents
Possible Cause(s)
Monolithic IC(s) (U100,
U101, U200, U201) blown.
Please note – U100 & U201
are only fitted to the LK140
Trip
Standby
Links at P10 & P11
connectors (found at left-
hand edge of board, roughly
½ way back) fitted at wrong
position or fitted when they
should not be.
Links at P10 & P11
connectors (found at left-
hand edge of board, roughly
½ way back) fitted at wrong
position or fitted when they
should not be.
Links at P10 & P11
connectors (found at left-
hand edge of board, roughly
½ way back) fitted at wrong
position or fitted when they
should not be.
Possible Cause(s)
This is normal and causes no
problem, as the fault only
occurs when the amp is not
connected to anything. As
soon as the input/output is
connected, the DC
disappears.
Monolithic IC(s) (U100,
U101, U200, U201) blown.
Please note – U100 & U201
are only fitted to the LK140
Cure
It is advisable to replace the
entire board, as blown
monolithics often destabilise the
board – repair is not normally
reliable.
The only link fitted should be
shorting together the two pins
marked 'Fit after burn-in'. All
other pins should be left unlinked.
The only link fitted should be
shorting together the two pins
marked 'Fit after burn-in'. All
other pins should be left unlinked.
The only link fitted should be
shorting together the two pins
marked 'Fit after burn-in'. All
other pins should be left unlinked.
Cure
No cure necessary.
It is advisable to replace the
entire board, as blown
monolithics often destabilise the
board – repair is not normally
reliable.
Copyright © 1999 Linn Products Limited. All rights reserved.