272 Chapter5
Troubleshooting the IF Section
Troubleshooting the A15 Motherboard Assembly
Table 5-6 A15 Motherboard Mnemonic Descriptions
Mnemonic Full Name Description
21.4 MHz IF 21.4 MHz IF The 21.4 MHz IF signal between the A9 Third
Converter assembly and the detector on the A14
Log Amplifier assembly.
+10V +10 V Supply The A7 Analog assembly provides a +10 V bias
supply for the LC bandwidth filters on the A11/A13
bandwidth filter assemblies.
+12V +12 V Supply +12 V supply for the A2 Display and the RS-232
option, referenced to DCOM.
+15VF +15 V Supply +15 V power supply, referenced to ACOM.
+5V +5 V Supply +5 V power supply, referenced to DCOM.
−15V −15 V Supply −15 V power supply, referenced to ACOM.
−8VT −8 V Temperature
Compensated
Supply
Provides −8 V from the temperature-compensated
(TC) power supply on the A14 Log Amplifier
assembly to the A7 Analog Interface assembly. The
A7 provides temperature-compensation for the
IFG4-IFG6 and the Log/Lin control lines using the
−8 VT as a TC reference.
ACOM Analog Common A common ground for all analog circuitry.
ADC_SYNC A/D Conversion
Synchronization
A positive-going signal that indicates when the
main ADC on the A16 Video/Processorassembly has
started an A/D conversion. ADC_SYNC resets the
peak detectors located on assemblies installed in
the 8590L, 8591C, 8591E, 8593E, 8594E, 8595E,
8596E, and 8594Q card cage.
ADR0-ADR4 Address 0-4 Input/Output (IO) address lines.
ANA_TEST Analog Test Provides a series of test signals from A7 Analog
Interface assembly to A16 Processor/Video
assembly during instrument calibration and
troubleshooting. (Refer to the A7 Overview Section)
AUX_IF Auxiliary IF An uncorrected, buffered 21.4 MHz IF signal from
the output of the A13 bandwidth filter assembly to
the four card-cage slots.
AUX_IF_BP Auxiliary IF Back
Panel
An uncorrected, buffered 21.4 MHz IF signal from
the output of the A13 bandwidth filter assembly to
J17, AUX IF OUTPUT.
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