you might be able to hook it to a computer to get fault codes? otherwise open it up and see if anything looks burnt
6.1.2 Dealing with Faults
The ALPHA 8410 “faults” into STBY or OFF when unsafe operating conditions
occur. This is shown when the amplifier changes from the OPR LED being ON to the
Fault and STBY LED’s If the 8410 encounters unsafe operating conditions, it enters a
protective “Fault” mode. When this happens, the tubes are biased off and the relays are
placed in the bypass mode, so that RF from the radio goes directly to the antenna. The
FAULT LED on the front panel will flash on and off for a period of about 4 seconds,
after which the amplifier will attempt to go back into OPERATE mode, unless the
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OPER/STBY switch has been placed in the STBY position. This 4 second period can be
shortened by toggling the OPER/STBY switch.
While the FAULT LED is flashing, the Ip and HV LED’s are used to indicate which
of the four fault conditions caused the amplifier to enter fault mode.
Fault type 1
Neither Ip nor HV LED’s are lit. Output relay did not close. This fault will rarely be
encountered, but if it is, it must be investigated further immediately, as continued
operation with this fault could cause additional damage to the amplifier.
Fault type 2
Ip LED is blinking. This indicates that the plate current in the tubes exceeded 1.5 amps.
This could be caused by the amplifier being mistuned or by overdriving the amplifier. If
neither of the above is the case, then a problem in the bias control circuitry may be
indicated.
Fault type 3
Both Ip and HV LED’s are blinking. This indicates that the gain of the amplifier has
fallen below 10 dB. This is an important safety feature of the amplifier, as many different
problems in the amplifier or with its operation can be detected as a drop in gain. To avoid
this fault occurring while the amplifier is being tuned up, the gain fault detection is
disabled when drive power to the amplifier is below approximately 20 watts. This allows
correct initial amplifier tuning to be achieved before going to full power.
Fault type 4
HV LED is blinking. This indicates a reflected power fault. The 8410 is set up to trip
when the reflected power exceeds approximately 300 watts. At 1,500 watts output, this
would represent an The fault type codes above are also reported in the amplifier telemetry
data via the serial or USB ports on the rear of the amplifier.
If the tube current exceeds about 2.5 amps, the amplifier is shut off completely- that
is, the AC is shut off. The ON/OFF switch will need to be used to put the amplifier
back on line. To avoid problems, wait at least 20 seconds after this occurs before
attempting to put the amplifier back on line. If the amplifier trips again immediately,
investigate and cure the problem before attempting to turn the amplifier on again.
Repeatedly hitting the ON switch when the amplifier trips out is likely to result in
severe damage to components in the amplifier.
If a hard fault trips the amplifier all the way OFF, wait at least 20 seconds before
turning the amplifier power on again
