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I
r
I
SYMPTOM
Stylus stays at one side
of recording channel while
instrument on
Erratic stylus motion
Low sensitivity
Non-linear
POSSIBLE CAUSE
Defective tube
Leaky condenser
Signal overload
Intermittent tube
Intermittent rectifier
Loose tube, plug-in, or
connector
Erratic signal
Intermittent circuit
element
Defective tube
Improper operation
Defective tube
No negative bias voltage
Mica condenser
Low 1ine vo 1tage
CHECK
Check tubes in defective
channel(s)
Check all mica condensers
If stylus returns to normal
with ATTENUATOR at OFF,
trouble probably coming in
from outside the instrument
Check all tubes
Check Y2001
Press in tightly
Check signal with meter and
oscilloscope
Check with meter and oscil-
loscope for intermittent
circuit element
Check all tubes
Check operating technique
Check all tubes
Check Y2001, R2003, C2007A,
Check mica condensers - lea
age across or through them
can alter grid bias
Check that line voltage is
within limits
Defective circuit element, Quick check:
measure for
giving incorrect circuit
approximately 1130 volts at
voltages
6V6 grids for quick check c
proper operating voltages
Signal
- 3 -
Signal having high-frequenc
components or fast pulses
n
not show on the recording,
but still drive tubes into
non-linear region
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