GE AMX-II

GENERAL ELECTRIC MEDICAL SYSTEMS AMX-11 X-RAY UNIT
7-1576 SM A0654E
SEC. 4 INVERTER DRIVER OUTPUT COUPLERS
41 60 Hz Inverter Driver Output Couplers.
Schematic reference sheet 2, Chapter 7.
The output of the 60 Hz inverter driver is coupled to the inverter as shown in Illustration 6-5. This volt-
age charges capacitor C through diode CR. The voltage developed across C is transferred to the SCR gate
through the Silicon Unilateral Switch (SUS). The SUS is a miniature SCR having an anode gate (instead
of the usual cathode gate) and a built-in avalance diode, between the gate and cathode. As voltage across
the SUS rises to the switching voltage point (7-9 volts for a 2N4990) the avalanche diode conducts and
triggers the SUS into conduction. The capacitor C discharges through the SUS and R2. The voltage ac-
ross R2 provides a peak pulse at the gate of the SCR for reliable triggering. Note the normal and abnormal
waveforms. The leading spikes may not be visible unless the scope is properly adjusted.
SCR
(a
= YO トー
F_ !
Lu | mm
NORMAL
-
SEE
W5
dr
6
y |
Ft
|
NOT NORMAL- SUS IS
372
NOT
FUNCTIONING
PROPERLY
SEC. Ri
CR
ILLUSTRATION 6-5
6-8