5-11
Teledyne Analytical Instruments
TT
TT
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Maintenance & Maintenance &
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SymptomSymptom
SymptomSymptom
Symptom CauseCause
CauseCause
Cause What What
What What
What TT
TT
To Doo Do
o Doo Do
o Do
Faulty triac (Q6) in heater
control or faulty triac driver (A4)
(continued.)
Cell lacks sensitivity (contin-
ued.) • Disconnect the thermo-
switch by removing one of
the wires from TS4
terminal 3. Meter should
show voltage.
• If voltage shows, short
terminals 3 and 4 with a
test jumper. Meter reading
should drop to about zero
(less than 10 VAC.)
• If power fails to go on and
off as jumper is alter-
nately installed and
removed between termi-
nals 3 and 4, the triac or
triac driver is probably at
fault and should be
replaced.
• If power does go on and
off, the thermoswitch (P/N
T22) is faulty and should
be replaced.
• If none of the above
improve the sensitivity,
replace the cell.