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Troubleshooting & Repair Teledyne API - Model 200EH/EM Operation Manual
258
11.5.7. KEYBOARD / DISPLAY INTERFACE
The front panel keyboard, the display and the keyboard/display circuit board can be verified by observing the
operation of the display when power is applied to the instrument and when a key is pressed on the front panel.
Assuming that there are no wiring problems and that the DC power supplies are operating properly:
The vacuum fluorescence display is working properly if, on power-up, a “-“ character is visible on the
upper left hand corner of the display.
If there is no “-“ character on the display at power-up but the
D1 LED on the relay board is flashing, the
keyboard/display circuit may be bad.
If the analyzer starts operation with a normal display but pressing a key on the front panel does not
change the display, then there are three possible problems:
One or more of the keys is bad,
The interrupt signal between the keyboard and the motherboard is broken or
The keyboard circuit is bad.
You can verify this failure by logging on to the instrument using APICOM or a terminal program. If the analyzer
responds to remote commands and the display changes accordingly, the display wiring or the I
2
C bus may be
faulty.
11.5.8. GENREAL RELAY BOARD DIAGNOSTIC
The relay board circuit can most easily be checked by observing the condition of its status LEDs as described in
Section 11.1.4.3, and the associated output when toggled on and off through the
SIGNAL I/O function in the
DIAG menu, see Section 6.13.1.
If the front panel display responds to key presses and D1 on the relay board is not flashing, then either the wiring
between the keyboard and the relay board is bad, or the relay board itself is bad.
If D1 on the Relay board is flashing and the status indicator for the output in question (heater, valve, etc.) does
not toggle properly using the
Signal I/O function, then the associated device (valve or heater) or its control
device (valve driver, heater relay) is malfunctioning. Several of the control devices are in sockets and can easily
be replaced. The table below lists the control device associated with a particular function:
Table 11-8: Relay Board Control Devices
Function Control Device Socketed
All valves U5 Yes
All heaters K1-K5 Yes
04521C (DCN5731)