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TABLE 4-7
WJ-8718A/MFP
Table 4-7. IF Interface Support Circuits (Contrd)
Support Circuit
Supports
Function
U20
U1*-U4*, U5, U6*
U7*, US, U9, U21
U23, U25
Bus transceiver
U21A
U16A, U16B
Select level register
U21B
U22
Remote/local latch
U22
U16A, U16B
Audio gain switch
U24A
U25
MGC signal strength amplifier
U24B
U25
AGC signal strength amplifier
U24C
U22
Current-to-voltage 'converter
amplifier
U24D
Manual gain
circuitry
RF gain amplifier
NOTE:
1-
NU denotes not used.
2.
* Components belong to modules used only when a standard
receiver front panel is in use.
3.
* * Serves to maintain integrity of the board.
4.1.4.2.1
4-16
IF Interface Troubleshooting Procedure
1.
Reference the following data to support Tables 4-8 and 4-9.
a.
Circuit descriptions in paragraph 3.2.5.
b.
Location of Components Diagram, Figure 5-10.
c.
Schematic Diagram, Figure 6-5.
d.
Modular troubleshooting concept described in
paragraph 4.1.4.1
2.
Recommended test equipment for trOUbleshooting IF Interface com-
ponents are an oscilloscope, digital voltmeter, ohmmeter (reference
the equipment list in the WJ-8718 Series HF Receiver Instruction
Manua!), and general purpose digital troubleshooting equipment de-
scribed in paragraph 4.1.3.1 of this supplement.
3.
The adjustable potentiometer R7 is unique to the IF Interface
modular structure and should be considered during troubleshooting
efforts.
Potentiometer R7 controls the range of the signal strength
levels, so that they fall within the required specifications and is
discussed in paragraph 4.1.2.2.
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