Power Failures - TA Instruments TMA 2940 Operator's Manual

Maintenance and Diagnostics

Power Failures

6–10
Fuse F2 protects the heater coils in the oven.
Because F2 does not power the internal logic,
you may not know that this fuse is blown until
you try to heat a sample, since the TMA instru-
ment will pass its confidence test with this fuse
open.
Fuse F2 is checked whenever a method is begun.
Power supplied by this circuit is switched by a
computer-controlled relay as well as the
HEATER switch located on the TMA front
panel. When both devices are active, the lamp in
the HEATER switch turns on.
A power failure caused by a temporary drop in
line voltage can result in one of two responses in
the instrument. If the drop is fairly large and of
long duration (20 milliseconds or more), the
system will reset and go into its power-up
sequence when power resumes. If the drop is
small or of short duration, the system may halt
and you may see "Err F02" on the instrument
display.
In the latter case, the system is "hung." It has
detected a power failure and shut down. The
TMA will not restart until it is reset. To reset,
press the Reset button on the instrument's back
panel.
If the power fail error code ("Err F02") appears
at startup and remains even after you have
attempted to restart the instrument, the detection
circuitry itself is probably at fault. Do not try to
repair it yourself; call TA Instruments for
service.
TA I TMA 2940
NSTRUMENTS