Acom ACOM2100 - Troubleshooting and Fault Diagnosis

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wattmeter current transformer TA1, and a high-pass lter RFCasw-Casw for frequencies below 100kHz,
to the antenna switch and the three outputs. The chokes RFC3 and RFCasw keep track of the antenna
relay contacts and together with Casw prevent the plate supply voltage from reaching the antenna. The
RF choke RFCasw shunts the high voltage to ground should the DC blocking capacitor Cb3 fail. The
resistor Rasw protects Casw from electro-static voltage build-up from the antenna.
The PLATE CAPACITIVE DIVIDER and RF WATTMETER are the main sources of information for the
control circuit of the amplier during the antenna impedance matching process. The control circuit is
based on the 80C552 micro-controller from Philips.
All supply voltages are delivered from the MAINS&LOW VOLTAGE and HIGH VOLTAGE SUPPLY PCBs.
The control grid, screen grid, and plate currents, plate cooling airow temperature, reected power, etc.
are continuously monitored by the micro-controller. Many software-derived protections are based on
this information.
* Detailed electrical schematic diagrams are available from ACOM or from your dealer on request.
6-5. Troubleshooting
See S.5-3 for the method of reading the auto-protection signatures. You can decode them using
the information below.*
The signatures are structured in two lines, three groups by six symbols for every one event of
auto- protection trip. The last event is numbered as 1A-1B pair of lines, and the oldest one is
7A-7B.
The meaning of the rst group is as follows:
a) nA - the number of the trip;
b) Next three symbols mean the following:
PN0 - tests made during Power-On procedure, before HV is ON;
PN2 - tests made during Power-On procedure, after HV is ON and one second after step-
start relay is closed;
SB0 - tests made in Stand-By, during the warm-up period or while entering Stand By (from
Operate);
SB2 - tests made during Stand-By, after the warm-up period;
PR0 - tests made while entering Operate;
PR2 - tests made during Operate;
TR0 - antenna relay tests made while changing from Tx to Rx (during Operate)
TR2 - antenna relay tests made while changing from Rx to Tx (during Operate)
TR4 - antenna relay tests made during Tx (Operate mode)
TR6 - antenna relay tests made during Rx (Operate mode)
c) The last symbol of the rst group designates the kind of the input parameter that caused the
protection circuit to trip. The abbreviations in brackets below are the signal names/designations
according to the CONTROL PCB electrical schematic diagram and signal type:
1 - peak forward power (pfwd, analogue)
2 - reected power (r, analogue)