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TROUBLE SHOOTING CHART
SANBORN DUAL CHANNEL DC AMPLIFIER
MODEL 150-2000
This chart assumes that the fault has been traced to the Dual Channel DC Amplifier.
SYMPTOM
Fuse blows each time
instrument turned on.
Does not work; tubes do
not light
Tubes light, but no oper-
ation all channels
No ,operation one channel
only, other channel normal
.'.,.'hO
POSITION control will not
move stylus over entire
recording channel
POSSIBLE CAUSE
Defective tube
Defective condenser
Defective transformer
Wrong size fuse
Blown fuse
Loose connectors
Defective tube
Loose connectors
Defective tube
Loose connector
Open resistor
Defective tube
Defective condenser
Matched resistor pairs
out of tolerance
No negative bias voltage
- 2 -
CHECK
Check V200l
Check plug-in condensers
C2006, C2007, also C200l
Check T200l, T2002
Must be 1.25 A Slo-Blo
Check F200l
Check that power connectors
P2002, P2Q03 at chassis top
and rear are firmly in plaCE
Check V200l
Check that signal circuit
connectors into J2004 and
J2005 are firmly in place
Check tubes in defective
channel
Check that signal circuit co
nector into J2004 or J2005
is firmly in place
Check R200l or R2002, R20l0,
R2011
Check tubes in defective
channel(s), including recti-
fier V200l
Check C20n
Check matched resistors
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