Model 250S1G6
Rev D
33
4.3.7
ALC Fault
Indication –
ALC
As stated previously, the power limit controls could not limit either the forward or reverse power to the preset
threshold. This can be a transient type of problem, if the fault can be cleared. If the fault cannot be cleared
with no RF input drive power, then there is a malfunction in the ALC board or associated circuit.
4.3.8
Low or No Power Output (DC Tests) (Schematic Diagram No.
10034514)
All indicators on the Model 250S1G6 are normal, the front panel display reads
RF On
, and the cooling fans
are operating.
1.
Check the position of the RF Gain control—is it set to maximum gain?
2.
Check the RF input to the unit—is it the correct amplitude and frequency?
3.
Check the RF output connection from the unit—is it correctly connected to the load?
Is the coaxial cable okay?
4.
Check the following voltages on the Power Supply. If any of the voltages are out of tolerance, correct
them before further troubleshooting.
PS1 C Module
+24.5 V
±
0.5 V
PS1 DB Module Channel 1 +24 V
±
0.5 V
PS1 DB Module Channel 2 -24 V
±
0.5 V
PS2
+24.5 V
±
0.5 V
PS3
+24.5 V
±
0.5 V
5.
Check the voltage on the feed thru caps of the A2 Driver Amp. Troubleshoot any incorrect voltage.
C2
+24.5 V
±
0.5 V
C1
-5 V
±
0.3 V
6.
Check the voltage on the feed thru caps of the A1 Pre-Amp, with the RF gain control at maximum gain.
Troubleshoot any incorrect voltages.
C4
+15 V
±
0.5 V
C3
-5 V
±
0.3 V
C1
+5 V
±
0.3 V
C2
-12 V
±
0.5 V
7.
Check the voltages on the feed caps on the A4-A7 and A12-A27 quad amps. Troubleshoot any incorrect
voltages.
C2
+24.5 V
±
0.5 V
C1
-5 V
±
0.3 V
C3
logic high (no fault)