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Power Supply/Midplane Troubleshooting
A7 Midplane Description
A7 Midplane Description
Purpose
The Midplane links the following major assemblies:
—A4 CPU Assembly
— A6 Power Supply Assembly
—A8 Motherboard
— A16 Reference Assembly
Refer to Figure 9-3. The Midplane Assembly (7) plugs into the Motherboard.
The CPU, Power Supply, and Reference Assemblies plug directly into the
Midplane board from the rear of the instrument. The Analog and Digital I.F.
Assemblies plug into the analyzer from the rear of the instrument into the
Motherboard itself.
Instrument Power Supply LEDs and Test Points
While the A6 Power Supply assembly has no user accessible LEDs or test
points the A7 Midplane board assembly does provide these for all of the
different instrument power supplies as well as many of the power supply status
lines. A complete list of these can be found in Table 9-4 and the location of
each can be seen in Figure 9-4.
Additional Power Supply Regulation
There are two analog power supply regulators on the A7 Midplane board
assembly. They are the +3.3VA and -5.2VA supplies. The +3.3VA supply is
regulated down from the instrument +5.1VA supply while the -5.2VA supply is
regulated down from the -7VA instrument supply. Both of these supply
voltages have test points and LEDs on the A7 Midplane board assembly as
seen in Figure 9-4.
Instrument Secure Storage
This is Non-volatile storage of instrument model number, serial number, and
software license keys. While the license keys are also contained on the C: drive
of the instrument, the model and serial numbers are only saved in this secure
memory. There is no way for the user to access this memory in any way. This is
reserved for the factory and field software when needed for instrument
initialization, as well as the instrument software when installing an option
license key. If for some reason any of these cannot be remembered by the
instrument there could be a problem with this memory and the A7 Midplane
board assembly would need to be replaced.
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