Mode Outputs - GE Medical Systems Corometrics 340 Service Manual

Mode Outputs

Pulsed Doppler Ultrasound Audio Converter
5-10
Calibration: Receiver Calibration
1. The mode output signals are generated via open collector transistor
switches in U2. For test purposes, the outputs must be connected to a
fetal monitor via the US, ECG and UA interconnect cables or pulled
up to +5 V (TP5) by 10kΩ resistors.
127( When testing the TOCO and IUP mode outputs, the receiver
front panel UA mode switch must be in the appropriate
position.
2. Refer to Table 5-3. Confirm operation of U2's internal open collector
transistor switches. Correct operation is a closure to ground at the
connector pins indicated. The transistor switch will be open if either
control signal is high.
Table 5-5. Open Collector Transistor Switch Testing
Signal Name Control Signals
USEN* TP1 and TP7 Low
MECGEN* TP1 and TP31 Low
FECGEN* TP1 and TP30 Low
TOCOEN* TP1 and TP5 Low
IUPEN* TP1 and TP5 Low
1. Feed a 1 Vp-p 300 ms burst of 300 Hz sine wave into J6 pin 2 (with
J6 pin 6 as reference); observe the waveform and its envelope at
TP14. Adjust the signal generator for an amplitude of 1.0 Vp-p at
TP14. With J201 pin 8 open, confirm the waveform at TP43
maintains the same envelope shape, but at half the frequency (150
Hz) as the signal at TP14. Confirm the peak-to-peak amplitude at
TP43 is equal to the amplitude at TP14 –0 + 0.6Vp-p.
2. Connect J201 pin 8 to ground and observe the waveforms at TP14
and TP43 are the same.
Model 340 Telemetry System
2006920-001
Reference Points UA Mode Switch
J201-11 and J10-12
J202-4 and J10-10
J202-2 and J10-3 Low
J203-12 and J10-11
J203-11 and J10-13
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TOCO
IUP
Revision A