Vector G08 Series Faq page 8

The circuit of D409, R410, and R411, in combination with IC900 on the HV board, is a spot-killer
that prevents the electron-beams from burning a hole in the phosphor surface of the CRT when the
monitor is turned off.
The outputs of the "X" and "Y" deflection amps can swing between +60V and -60V. This voltage
is high enough to provide up to 8 amps, peak-to-peak, of current through the deflection coils. The
power input of the deflection board is an isolated +45V Center Tap.
One of the most important things to watch on these monitors is the input power. Input voltage is 91
VAC nominal. You are better off running lower than higher. If the input voltage is too high, the
rectified voltages for everything also increases, and overvoltage may cause problems for some
parts, especially the deflection transistors.
The low voltage power supply section creates the following voltages:
•
+/-63 VDC (goes to X-Y power amplifiers)
•
+55 VDC to RGB video drivers and spot killer
•
+/-9.1 VDC to the IC's
•
+126 VDC to the EHT oscillator
When you look at your deflection board and your schematics, you may notice some discrepancies
and ask "Where is part x?"
• R636, R637, R736, and R737: On issues 1, 2 and 3 deflection boards, these resistors should
be found on the bottom of the deflection PCB, or possibly the current limiting boards.
• C726: The capacitor C726 is typically found in parallel across R726 (either over the resistor
itself, or soldered to the bottom of the board). C626 is attached in the same manner.
• Diode near R726: Sometimes there is no diode near R726. The diode is a 1N914. If you
want to insert the diode, simply place the board in a position where the current limiting
boards are on your left. Lift the right leg of the resistor, and attach the banded end of the
diode away from the resistor, and place the end of the diode in the hole the resistor leg was
in.
• D701, D702, D601, D602: These diodes are a bit of a mystery. They originally appeared
in the G08-001 and G08-003 schematics in the "Sega/Gremlin Color X -Y Monitor" manual,
but then dropped out of the "Preliminary Service Data G08-003/004 X-Y Color Monitor"
manual's parts list and schematics. If they are missing, don't bother installing them.
Pin # Connection
1 45 VAC
2 Center Tap
3 45 VAC
G08 Vector Monitor Guide
Page 8 of 41