Linn LK260, Руководство по обслуживанию

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Paul O’Neill Copyright © 2000 Linn Products Limited. All rights reserved.
LK2 6 LK275 Rel ab li y o i i ations LK2(60) & LK275 Reliability Modifications
Some components on the PCAS 003 (used in the LK260 & LK275) are
sometimes prone to failure after many years of use.
This modification can be carried out as a preventative measure to prolong
the life of the amplifier or as a combined repair / prevention if one of the
components has failed.
Carrying out this modification will repair around 60 – 70% of LK2 faults
Important Information about this modification
•
Please read through this procedure in its entirety before starting any work.
•
It is important to follow ALL instructions carefully and exactly
•
This procedure involves soldering and de-soldering and it is advised that only personnel with a
fairly high degree of soldering skill undertake this task. Due to the age and the years of heat
stress – some of the solder joints may have changed their chemical properties and if this is the
case it will be quite difficult to melt them. Use flux (or melt new solder onto the old solder joint),
Use heat and patience - not force.
•
The changes outlined in this procedure will protect the LK2 from similar potential failures in the
future by using higher wattage resistors than were originally used and adjusting the position of
some components to minimise heat damage
•
It is advised that all these modifications are carried out to both channels.
Estimated time for completion of this task:
1 hour
CAUTION – Important Safety Information
•
Residual Voltage . With certain faults especially but also under normal circumstances, there can be
residual voltage stored in the boards which could cause quite a serious electric shock. To avoid this, it is
best to leave the LK2 switched off for a few hours before starting work on it and then using a voltmeter,
measure across the metal contacts of each of the big capacitors (DO NOT TOUCH) on each channel
(DC voltage). If there is a voltage remaining on these capacitors then it is important to discharge it –
either short across the + & - contacts with a screwdriver – this can cause a harmless but spectacular and
terrifying bang combined with a huge spark. It is much more pleasant to connect one of the resistors that
you will use for the mod – the 2.4Kohm/2.5Watt and connect this across the contacts of the capacitors
until the voltage has discharged.
•
The LK2 is very heavy and has sharp fins on the heatsink – be very careful when lifting, handling,
dismantling and re-assembling not to injure yourself.