Teledyne GFC-7000E - Trace CO2 Analyzer - Manual (Page 217)

Model GFC7000E Instruction Manual TROUBLESHOOTING & REPAIR PROCEDURES
04584 Rev A1 206
Connect a jumper from the +5 pin on the Status connector to the x5V on the Control In
connector.
Connect a second jumper from the ‘-‘ pin on the Status connector to the A pin on the Control In
connector. The instrument should switch from SAMPLE mode to ZERO CAL R mode.
Connect a second jumper from the ‘-‘ pin on the Status connector to the B pin on the Control In
connector. The instrument should switch from SAMPLE mode to SPAN CAL R mode.
In each case, the MGFC7000E should return to SAMPLE mode when the jumper is removed.
11.4.8. CPU
There are two major types of failures associated with the CPU board: complete failure and a
failure associated with the Disk On Chip on the CPU board. If either of these failures occur,
contact the factory.
1. For complete failures, assuming that the power supplies are operating properly and the wiring
is intact, the CPU is bad if on powering the instrument:
• The vacuum fluorescent display shows a dash in the upper left hand corner.
• The CPU Status LED, DS5, is not flashing. (see Section 11.1.4.1.)
• There is no activity from the primary RS-232 port (COM-A) on the rear panel even if “?
” is pressed.
• In some rare circumstances this failure may be caused by a bad IC on the Motherboard,
specifically U57 the large, 44 pin device on the lower right hand side of the board. If this
is true, removing U57 from its socket will allow the instrument to startup but the
measurements will be incorrect.
2. If the analyzer stops part way through initialization (there are words on the vacuum
fluorescent display) then it is likely that the DOC has been corrupted.
11.4.9. RS-232 Communications
11.4.9.1. General RS-232 Troubleshooting
Teledyne Instruments analyzers use the RS-232 communications protocol to allow the instrument
to be connected to a variety of computer-based equipment. RS-232 has been used for many
years and as equipment has become more advanced, connections between various types of
hardware have become increasingly difficult. Generally, every manufacturer observes the signal
and timing requirements of the protocol very carefully.