Vector G08 Series Faq page 11

The pinouts for the HV 10-pin header are as follows:
The HV PCB has three controls on it: R917 (frequency control), R918, and R933 (sensing voltage).
Frequency control regulates the voltage the transformer puts out. Sensing voltage controls the level
at which the HV supply will shut itself off to prevent a dangerous, X-ray producing overvoltage
condition. R918 provides a sensitivity setting for shutting down the HV when the beam is not
changing. Some manuals incorrectly reference R933 as R920. R920 was the G08-001 name for
this control.
The large control on the HV unit (R922) is the focus control.
The small PCB affixed to the outside of the metal cage is a voltage regulator, which regulates the
input between +100VDC and +126VDC.
IC900 on the HV unit is a high-voltage oscillator. This is Electrohome part number 14-002155-01
(EHT Control Circuit), and is another custom Sega part (Sega Part number 315-0118). This IC
operates the high-voltage transformer, T901. This transformer is technically a flyback type, but it is
not used to deflect the beam. IC900 serves two other functions; it senses the presence of the
10.3KV through R921 and R932 and compares it against the 9.1 supply voltage to ensure a
regulated output, and also senses the varying current in either deflection coil. If no change is
detected, the IC shuts down the high-voltage oscillator to prevent the beam from "burning" the face
of the CRT.
The HV transformer (T901) is otherwise unavailable for replacement. These HV transformers are
extremely reliable compared to all other vector monitors out there, but if yours does go bad, you
will have to find another G08 HV cage for a replacement.
Pin # Description
1 Y
2 X
3 -9.1 VDC
4 +9.1 VDC
5 GND
6 GND (heater)
7 +6.3 VAC (heater)
8 +126 VDC
9 NC
10 VG2 (variable gain;
part of brightness circuitry)
G08 Vector Monitor Guide
Page 11 of 41