Display ASM
Much of the miscellaneous digital control is performed by
A2UlOO.
UlOO
functions as the
display ASM (algorithmic state machine) and character ROM. It also converts the 16-bit CPU
data bus to an 8-bit data bus for the rest of the spectrum analyzer.
Display/Power Supply
Section
A6 Power Supply
The A6 power supply is
a
switching supply operating at 40 kHz for the low voltages and
30 kHz for the CRT supplies (cathode, filament,
+llO
Vdc, and post accelerator).
A6Al
high
voltage module contains the high-voltage transformer and post-accelerator multiplier. Power
is distributed through W8 to Al7 and through
Wl
to the rest of the assemblies.
A6AlW2
supplies CRT cathode and filament voltages to the Al7 assembly.
The speed of the spectrum analyzer fan is variable. A thermistor on A6 senses the
temperature and adjusts the fan speed accordingly. This allows the spectrum analyzer to run
quietly in most room-temperature environments and faster (louder) only when necessary.
Al7 CRT Display Driver
The line generators on the A2 assembly drive the Al7 CRT driver. The Al7 assembly
contains X and Y deflection amplifiers, focus and intensity grid amplifiers, and miscellaneous
CRT bias circuitry. The high voltage is supplied by
A6Al
high voltage module.
In fast-analog zero-span mode (sweep times
530
ms without Option 007), the O-SPAN VIDEO
signal from A3 and the sweep ramp from Al4 connects to the Al7 CRT driver. The graticule
and annotation are still digitally drawn.
General Troubleshooting 7-51