Vector G08 Series, Faq, Page: 10 / 42

G08 Vector Monitor Guide
Page 10 of 41
that by looking at just numbers, you need to see a breakdown chart. This will show you where
secondary breakdown is.
For example, looking at the 2N3716 data sheet you will see that at full voltage (80 volts) the part
will withstand 0.2 amps. That is only 16 watts allowed for what is supposed to be a 150-watt part!
Compare that with a 2N6259 that can take 200 watts of dissipation with 90 volts across the part!
It is about a 200-watt part and you can dissipate ALL OF IT with 90 volts across the part!!! A
normal transistor would go into secondary breakdown (definition: localized melting of the junction
due to current hogging - very destructive) at 20 to 40 volts. There are VERY few transistors that
even come close to what this thing can do.
What kills the 2N6259 is over voltage, plain and simple. The part is rated for (I think) 125 volts,
maybe as high as 150. However, the G08 uses +/-63 volts IDEALLY. So when the amplifier
swings to the rail during a fast vector draw you have close to 125 volts.
Remember I said IDEALLY? That is with the game plugged in to a 110-volt line, since that is what
the Gremlin/Sega power transformer was designed for. Are there any of you with only 110 volts
coming out of the wall? More like 120 to 130, isn’t it? THAT is why I keep saying the game needs
to be re-strapped to match the power line. Either buck out the extra voltage with some filament
transformers or whatever, but DO reduce the voltage. And what happens when the occasional
power line spike comes along? The monitor blows up, that’s what.
In my Showbiz Pizza days we used to use NTE388’s in an Eliminator at about $10 per part. They
still blew up until one of the techs (not me) ran the power into the 110 and 240 taps of the game
power transformer. The result was a 130 volt winding. The transistors quit blowing. It was just that
simple.”
There might be a 100-Ohm resistor placed across the terminals of the deflection transistors. I have
no idea what to say about this other than "some do, some don't". This resistor(s) do not show up in
the schematics, and I have no idea what effect these resistors have on the circuit.
HV Unit
The High Voltage (HV) unit creates the high voltage for the tube as well as the AC voltage for the
CRT heater. The HV unit consists of a PCB mounted in a metal box. The PCB has a HV
transformer mounted on it. A small PCB (1” x 2”) is mounted to the outside of the box; this PCB is
the HV Regulator PCB. The HV is mounted in a metal frame and has a 10-pin header at the top.
The deflection board plugs in here.