Wells-Gardner D9300 Series - Manual (Page 22)

Wells-Gardner Electronics Corporation
20
Q317, Q318 are off when horizontal frequency is 53KHz a 61KHz
Q316, Q317, Q318 is off when horizontal frequency is 62KHz a70KHz
8-6 FBT (Flyback Transformer):
The high voltage for CRT anode focus, G2 voltage for CRT and – 12V for vertical
deflection are generated by the FBT. Also, -130V for G1 voltage, horizontal flyback
pulse, +128V video supply, and for dual focus units 800V dynamic focus supply.
8-7 ABL (Automatic Beam Limiting):
The voltage of point 7 depends on the anode current of FBT. So, the voltage at pin 7
of the FBT decreases with increasing anode current. That time, using at this level,
increase contrast setting level limited a certain level (32FtL in white pattern) that is
set by inner voltage of IC401.
8-8 Video amplification section:
8-8.1 Video pre-amplifier(IC401).
Input video signals are amplified by means of IC401, and the amplified signals drive
the video output stage (IC402). Video gain is adjusted by DC voltage at pin 12 for
ABL control.
8-8.2 Video output stage (IC402).
The video output signals from IC401 are amplified again by IC402, and IC402
applies video signals to each cathode of the CRT. Cutoff voltages are adjusted by
Q405, Q406 and Q407 which is operated by I²C BUS control through the
microprocessor.
8-8.3 OSD (On Screen Display : IC403).
The OSD signal is applied from IC403 to IC402. It is controlled by I²C BUS control
line.