Datex-Ohmeda CAPNOMAC ULTIMA, Руководство по обслуживанию

Страница: 148 / 232

CAPNOMAC ULTIMA
TM
SERVICE MANUAL
6-19
6.4.7
CPU board troubleshooting
Due to the complexity of the LSI circuitry there are few faults in
the CPU digital electronics that can be located without special
equipment. The following checks may be performed:
a )
The
RAM, EPROM,
CPU, and other socketed I.C.s are
properly installed and the memory configuration jumpers
are correct (see Figure 5.16).
b )
The 11.059 MHz (rev. 05 and below) or 16 MHz (rev. 06
and up) clock signal at the CPU pins 18 and 19 (use a high
impedance probe to check) is present.
c )
PSEN (CPU pin 29) shows that instructions are being
fetched. If this line is static, the processor is not running.
d )
RESET (CPU
pin 9) is normally low, but pulled up to +5 V
for a moment after power up. If RESET is constantly high,
check the +5 V supply line for spikes or low voltage.
The analog part is somewhat easier to troubleshoot. The input
analog voltages are easily tracked to the MUX input. After the
MUX, the voltages are multiplexed so that the resulting waveform
is of 200 - 600 Hz frequency.
IR analog output is updated every 10 ms. All other analog output
channels are updated every 40 ms. Thus the D/A conversion
interval is 5 ms.
6.4.7.1 Instructions after replacing the software or CPU board
After replacing the software or CPU board:
perform the gas calibration.
re-establish previously used settings or inform the monitor
user that all other settings are default values.
January 15th, 1997/6