Theory of Operation
4–6
ECO 422
front panel. The Controller gets a timing signal from the Timer circuit. It counts
this signal to check the inactivity of the front panel. Every time that a front-panel
key is pressed the internal counter is reset. If the counter reaches one minute, the
front panel is automatically locked out.
Reference Voltage and Selector Switch Farm 9
VREF
for each
channel
+12 V
+5 V
Figure 4–4: Reference Voltage and Selector Switch Farm Block Diagram
Reference Voltages.
The +2.5 V reference voltage is provided by U31. This
signal is used to produce the –2.5V_REF and the Attenuation signals.
The +2.5 V signal from U31 is combined with ATTEN_SW and buffered by
U23B and U20B. The resulting signal is set to the Switch Farm as ATTEN_M
and ATTEN_C to control the input attenuators.
The –5 V signal is inverted and buffered by U20A, resulting in the –2.5V_REF
signal. This signal drives five inverting amplifiers, each with a DC output
equivalent to the recovered DC from the Peak Detector Buffers for a specific
type of input. It also drives two adjustable amplifiers whose amplitude is
adjusted by R266 and R265. The results are the BUFX signals that are connected
to the Switch Farm by S14–1 through S14–7.
Switch Farm.
The Switch Farm, S1–S11, is a set of 11 eight-bit DIP switches, one
for each channel. The user selects which reference amplifier, VREF, for each
channel using the switches and whether or not the attenuator, ATTEN, is
inserted. Opening the seven reference amplitude switches allows VREF to go to
Summary of Contents for ECO 422
Page 4: ......
Page 6: ......
Page 14: ...General Safety Summary viii ECO 422 ...
Page 16: ...Service Safety Summary x ECO 422 ...
Page 17: ...Getting Started ...
Page 18: ......
Page 31: ...Operating Basics ...
Page 32: ......
Page 41: ...Operating Basics ECO 422 2 9 Figure 2 6 Setup for Adjusting R265 the User Level for SX 7 ...
Page 43: ...Specifications ...
Page 44: ......
Page 52: ......
Page 53: ...Theory of Operation ...
Page 54: ......
Page 62: ...Theory of Operation 4 8 ECO 422 ...
Page 63: ...Performance Verification ...
Page 64: ......
Page 84: ...Performance Verification 5 20 ECO 422 ...
Page 85: ...Adjustment Procedure ...
Page 86: ......
Page 88: ...Adjustment Procedure 6 2 ECO 422 ...
Page 89: ...Maintenance ...
Page 90: ......
Page 101: ...Options ...
Page 102: ......
Page 104: ...Options 8 2 ECO 422 ...
Page 105: ...Replaceable Electrical Parts ...
Page 106: ......
Page 140: ...Replaceable Electrical Parts 9 34 ECO 422 ...
Page 141: ...Diagrams Circuit Board Illustrations ...
Page 142: ......
Page 145: ......
Page 147: ... ECO 422 Changeover Unit FRONT PANEL 1 ...
Page 148: ...ECO 422 ...
Page 166: ...ECO 422 ...
Page 167: ...Replaceable Mechanical Parts ...
Page 168: ......
Page 174: ...Replaceable Mechanical Parts 11 6 ECO 422 ...
Page 175: ......
Page 176: ...ECO 422 A1 FIG 1 EXPLODED VIEW A2 A3 A4 ...
Page 177: ......