Lambda Electronics 71 Instruction Manual - page 17
If upon removal of any tube
V2-V6, this condition is
eliminated, replace this
faulty tube with a new tube.
2) Filament burnout of 12AX7.
V8. lf tubes V2-V6 ere all
found to be good, the 12AX7,
V8 may have a burned out
filament. This is slmply
checked for by replacing the
l2AX7 with a new tube.
3) Loss of bias supply voltage
will result in rise of output
voltage. If bias supply output
voltage approaches zero volts,
and 5651, V14 is extinguished
and voltage across C5A is zero,
the bias supply system fuse,
F1, 1/2 A has failed. Insert
a 1 Ampere AC ammeter in place
of the fuse and turn on the
supply. lf current exceeds
0.4 Amperes check 6X4, V10 for
short or gassy condition, and
C5A, CSB for shorted capacitors.
If any of these components are
found to be faulty, replace
these components.
4) Absence of voltage across
filter capacitors C5A, C5B.
check V10, 6X4 tube for open
or burned out filament. This
is most simply accomplished by
replacing tube with a new tube.
5) Presence of bias supply
input filter voltage and
absence of supply output
voltages a) 6W6—GT, V1
filament is burned out, replace
tube.
b) Filament burnout of 12AX7,
V12. This is easily checked
for by replacement with e new
tube.
15.