Teledyne 6200E - Sulfides Analyzer - Manual (Page 261)

Model 6200E Instruction Manual TROUBLESHOOTING & REPAIR
M6200E Rev: A1 261
IZS_TEMP signal voltage using the SIGNAL I/O function under the DIAG Menu (Section 6.9.2).
At 50°
C, the temperature signal from the IZS thermistor should be around 2500 mV.
11.5.17. Box Temperature
The box temperature sensor (thermistor) is mounted on the motherboard at the bottom, right
corner of the CPU board when looking at it from the front. It cannot be disconnected to check its
resistance. Box temperature will vary with, but will always read about 5° C higher than, ambient
(room) temperature because of the internal heating zones from the H
2
S converter, sample
chamber and other devices. To check the box temperature functionality, we recommend to check
the
BOX_TEMP signal voltage using the SIGNAL I/O function under the DIAG Menu (Section
6.9.2). At about 30° C (5° above typical room temperature), the signal should be around 1500
mV. We recommend to use a certified or calibrated external thermometer / temperature sensor to
verify the accuracy of the box temperature.
11.5.18. PMT Temperature
PMT temperature should be low and constant. It is more important that this temperature is
maintained constant than it is to maintain it low. The PMT cooler uses a Peltier, thermo-electric
element powered by 12 VDC from the switching power supply PS2. The temperature is controlled
by a proportional temperature controller located on the preamplifier board. Voltages applied to the
cooler element vary from +/- 0.1 to +/- 12 VDC. The temperature set point (hard-wired into the
preamplifier board) will vary by about ±1° C due to component tolerances. The actual temperature
will be maintained to within 0.1° C around that set point. On power-up of the analyzer, the front
panel enables the user to watch that temperature drop from about ambient temperature down to
its set point of 6-8° C. If the temperature fails to drop after 20 minutes, there is a problem in the
cooler circuit. If the control circuit on the preamplifier board is faulty, a temperature of -1° C is
reported.
11.6. Repair Procedures
This section contains some procedures that may need to be performed when a major component
of the analyzer requires repair or replacement. Note that replacement procedures that are
discussed in detail in Chapter 9 (Maintenance) are not listed here. Servicing of circuit components
requires electrostatic discharge protection, i.e. ESD grounding straps, mats and containers.
Failure to use ESD protection when working with electronic assemblies will void the instrument
warranty.
11.6.1. Disk-on-Chip Replacement
Replacing the Disk-on-Chip (DOC) will cause all of the instrument configuration parameters to be
lost unless the replacement chip carries the exact same firmware version. If the analyzer is
equipped with at least one EEPROM flash chip, the configuration settings are stored in a backup
file on the EEPROM. It is recommended to document all analyzer parameters that may have been
changed, such as calibration, range, auto-cal, analog output, serial port and other settings before
replacing the chip.
1. Turn off power to the instrument, fold down the rear panel by loosening the mounting screws.
2. When looking at the electronic circuits from the back of the analyzer, locate the Disk-on-Chip
in the right-most socket of the CPU board. The chip should carry a label with firmware