Linn LK260, Руководство по обслуживанию

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LK2 Service Manual
Page14
Copyright © 2000 Linn Products Limited. All rights reserved.
Contents
Paul O'Neill
No output from
one channel Applies only to
earlier versions of
LK260
Probably constant
Power transistor (the large
transistors clamped to the
heatsink) faulty.
It is sometimes possible to
measure these transistors
using an ohmmeter to check
if faulty (usually internal
short-circuit across one or
more of the junctions), but
also there is the possibility
that the transistor measures
okay but is indeed faulty.
It will sometimes be
necessary to change them to
confirm or rule out this fault. Check / replace power
transistor(s).
Parts may be as listed in the box
above or they may be as listed
below, depending on whether it is
an earlier or later version of
LK260.
Part details –
Q20 & Q27 – TIP36C; PNP;
100V; 25A; TO218 (Linn part no:
TRAN 005)
Q24 & Q31 – TIP35C; NPN;
160V; 15A; TO218 (Linn part no:
TRAN 004)
No output from
one channel May be intermittent Regulator U1 or U2 faulty Replace faulty regulator – part
details:
U1 – LM317T Voltage regulator
(Linn part no: IC 005)
U2 – LM337T Voltage regulator
(Linn part no: IC 006)
No output from
one channel Applies to LK280
only
May be intermittent
or may be constant
U3 (hybrid card) faulty. U3 is
the small board that is
connected at 90degrees to
the main board beside the
big caps. Replace U3 – Linn part number
IC 030 (not available elsewhere).
Take great care when removing
U3 from the board as it is very
easy to rip tracks. The pins in the
middle are especially difficult to
de-solder – use heat & patience –
not force.
It is also worth checking /
replacing regulators U1 & U2
(part details above) and the big
resistors at either side – R37 &
R46 – part details: 0.1ohm; 10%;
2.5W; 100V. (Linn part no: RES
050).
No output from
one channel May be intermittent Faulty component in circuit. See “ Fault Finding on the LK2 –
hints & tips ” section at the
beginning of this manual.