LI-COR LI-6400, Manual

Page: 559 / 846

Troubleshooting
Chamber Problems
Using the LI-6400 20-33
Chamber Problems
The Mixing Fan
The chamber mixing fan is shown in Figure 19-26 on page 19-31. It is pro-
tected by a fuse (Figure 19-8 on page 19-11), but problems with the fan motor
can also cause the flow board fuse to blow.
■ ■ ■ ■
To verify normal operation
Use your ears. Turn the fan off and on in New Measurements mode, and you
should hear the sound change. (The fan control is via
f3 level 3.)
If the fan isnÕt behaving normally, then hereÕs some things to check:
1 Fan motor burned out?
This typically causes a flow board or fan fuse to blow, but not until the first
time New Measurements mode is entered, because that is when the system
turns on the fan for the first time.
To verify the motor is burned out, you can measure the impedance across pins
25 and 26 of the 26 pin D connector (Table 20-1 on page 20-45) on the back
of the chamber/IRGA. Pins 25 and 26 are on the bottom row, right hand end.
It should be about 63 Ohms. If it is 0 Ohms, you need a new motor.
An alternate way to check this is to use the program Control Panel (see ÒCon-
trol PanelÓ on page 21-10). Power the LI-6400 on, press
escape
to prevent
OPEN from loading, access the Filer, select the
/Sys/Utility
directory, and run
Control Panel. Turn on the flow board (item 2), then turn on the fan (item 7 =
5000, then item 6). If that doesnÕt blow a fuse, try turning on the pump as well
(item 9 = 4500, then item 8).
2 Fan blades jammed?
This should cause the fan fuse to blow. To remedy the situation, open the
IRGA sample cell (
Cleaning the Optical Bench on page 19-28) and clean
the debris from under the fan blades.
3 Connector or cable problem?
Check the 26 pin D connector on the back of the chamber/IRGA to make sure
that no pins have been pushed in, or been broken, etc. If possible, try a differ-
ent cable.
A replacement motor and fan is available as part number 6400-902.