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REPLACEMENT PROCEDURES (continued)
4.18
Alarm Channel
Replacement of the alarm circuit board or the system power switch assembly
requires that the alarm channel be removed from the machine. The top of the
alarm channel is held in place by the cover plate which also retains the
flowmeter shield. On later models the vapor box cover plate is extended to also
cover the flowmeter shield and alarm channel. The bottom of the alarm
channel is held by a screw from the back. Access to the bottom mounting screw
and the alarm channel connections requires removal of the rear cover. Figure
4-18 shows a rear view of the alarm channel and the arrangement of the
circuit board assembly and system power switch.
4.18.1
Disconnect the pipeline hoses and close all cylinder valves.
4.18.2
Press the O
4.18.3
Set the System Power switch to STANDBY and remove AC power
from the machine.
4.18.4
Remove the screws holding the rear cover, and remove the cover.
4.18.5
Remove the screws holding the table top, and lift out the table top.
CAUTION: The circuit board contains static sensitive devices. Use
4.18.6
Disconnect the cables from J1, J2, J3 and J4 on the alarm circuit
board.
WARNING:
4.18.7
Disconnect the two compression fittings at the system power switch
valve.
4.18.8A Early models: Remove the two screws (from the back) holding the
angled cover plate at the top of the channel. Hold the cover plate as
the screws are removed from the back.
4.18.8B Later models (without the O
screws holding the flowmeter shield and vapor box cover, and remove
the panel.
4.18.9
Feed the flowmeter lights wire harness through the hole at the top of
the alarm channel.
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Flush valve to drain oxygen pressure from the system.
2
ESD protection when handling this assembly.
Ensure that AC power is removed from the
machine before disconnecting the cables. Failure
to observe this precaution may cause injury by
electric shock.
/N
O ratio alarm lamp): Remove the six
2
2
4-66
NM3
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Troubleshooting
