Mode Controls - GE Medical Systems Corometrics 340 Service Manual

Mode Controls

5-8
Calibration: Receiver Calibration
dB AC DC
UNITS VOLTS VOLTS
1. Confirm the low-pass filter –3 dB cutoff point of 90 ± 6Hz with an
input of 1.0 Vp-p at TP45 and the output at TP21. Set R61 for a gain
of 2.3.
2. Adjust R177 for a frequency of 8020 ± 20Hz at TP32.
3. Confirm a 10 ± 0.1 Vp-p, 4010 ± 20 Hz square wave at TP33.
4. Confirm the center frequency and the –3 dB points of the switched
capacitor bandpass filters for each IC listed in
Table 5-2. Band-Pass Filter Center Frequencies and –3 dB Points
IC Reference
U17-6
U18-6
U23-6
U27-6
5. With no signal applied, adjust the tone decoders for the correct center
frequency indicated in
Table 5-3. Center Frequencies of Tone Decoders
Test Point
TP6
TP8
TP9
RP11
Model 340 Telemetry System
2006920-001
888 888 888 888 888 888
Hz Generator Hz Counter
Center Frequency
80 Hz
40 Hz
20 Hz
10 Hz
Table 5-3.
Center Frequency
10 Hz
20 Hz
40 Hz
80 Hz
Table 5-2.
–3 dB Point
75 Hz, 85 Hz
35 Hz, 45 Hz
15 Hz, 25 Hz
5 Hz, 15 Hz
Adjustment
R95
R99
R110
R149
Revision A