BIRD Termaline 8792 Series, Operation Manual

Page: 21 / 30

Maintenance
10
Troubleshooting
For corrections requiring repair or replacement of components, refer to the appropriate section for your specific
model.
Problem Possible Cause Correction
Repair
Replacing a Resistive Element
This series of water-cooled loads is designed to be quickly and easily repaired in the field. If in performing the
RF
Assembly Resistance Test
described previously, a significant change in resistance is noted, or if for any reason the
resistive element should fail, inexpensive replacement resistors are available. They can be installed in the load,
using the following procedures:
Note:
stem numbers enclosed in brackets [ ] in the text are indicated on
Figure on page 16
,
Figure 3
on page 13
, and
Figure 4 on page 13
.
Note:
Turn off RF Power and interlock circuitry prior to proceeding.
1. Ensure the water flow has been turned off before any disconnection.
2. Disconnect the water hoses at the hose fittings [2] on the load. See
Figure on page 16
.
3. Disconnect the unit from the RF transmission line.
4. Completely drain excess water from the load.
5. Set the load on end with RF Connector down.
6. Remove the water chamber [1] by unscrewing it in a counterclockwise direction.
Note:
A strap wrench and a 3/8 to 1/2 inch rod are useful to overcome the initial tension of the water
chamber item [1]. The rod is inserted in the water output hose nipple fitting item [2] for leverage.
Note:
The water inlet tube will usually come out with the water chamber. If not, perform the next
step.
7. Pull the water inlet tube [4] straight off.
Transmitter shuts off or
will not stay on.
Note:
This applies to
units with flow inter-
lock only.
Low or no water flow Increase cooling water flow.
Faulty Flow Switch Perform
"Preoperational
Checkout" on page 5
. If
switch fails to operate,
replace switch, see
"Replacing the Water Flow
Switch" on page 14
High load VSWR. Failing resistor Perform
"RF Assembly
Resistance Test" on page
9
. Resistance change of
greater than 5 ohms
indicates a failing resistor.
Replace resistor, see
"Replacing a Resistive
Element" on page 10
.
Loose input connector. Tighten connector.
WARNING
The resistor used in this load consists of a resistive film on a special substrate. If the
substrate is broken, there will probably be sharp pieces or splinters inside the load
housing. Caution should be exercised to avoid possible injury.