Keysight N9038A MXE Service Guide 275
Front End Control
A15 Front End Control Assembly Troubleshooting
Assembly Control Verification - (Option 503, 508, & 526 only)
In order to verify the different control signals that the A15 Front End Control
assembly provides to the Front End components of the instrument a test board
is required and has been made available. A kit containing this test board and
the required cables can be purchased as part number N9020-60005 from
http://www.keysight.com/find/parts
. The contents of this kit are contained in
Table 8-3.
The connections to the test board and the associated circuitry for the
verification of the different assemblies can be seen in Figure 8-3. This will also
be further explained in the procedures that follow.
The following procedures will describe how to use this board to determine if
the control circuitry on the A15 Front End Control assembly is working
properly. It is recommended that this be done prior to the replacement of any
of the assemblies that the A15 Front End Control assembly controls.
This test board is only intended for use with instruments that have either Option 503, 508, or
526; it will not work with instruments that have Option 544 due to the differences in the front
end assemblies used.
Table 8-3 Contents of Kit Part Number N9020-60005
Keysight Part Number Description
E4410-60115 Front End Control Test Board Assembly
E4410-60156 A13 Front End Assembly Control Cable
E4410-60157 A9 / A10 Input Attenuator Control Cable
E4410-60158 A12 YTF Preselector Control Cable
E4410-60160 A11 RF Switch / High Band Preamp Control Cable
When being used to verify the control signals to the A13 RF Front End assembly there are many
resistors on the Front End Test board that can get VERY HOT. Be careful not to touch them or
place any combustible objects in contact with them. Also, do not leave the instrument
unattended while powered on with the Front End Test board connected in this manner.
When making Main Coil Current measurements R119, R120, and R121 on the Front End Control
Test board can get VERY HOT. Be careful not to touch them or place any combustible objects in
contact with them. Also, do not clip test leads to P8 and leave the instrument unattended while
powered on.
Do not connect or disconnect the Front End control test board assembly to or from the
instrument while it is turned on. This can cause damage to either the A15 Front End Control
assembly or the assemblies that it controls. Be sure to always turn the instrument power before
any connections are made or broken.
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