Power Supply Transformer: Connections

The transformer that was installed in several Sega G80 system games has 4 "taps" on the primary winding. The taps are positioned at intervals along the winding to allow for different AC supply voltages. The taps that the two AC leads get plugged into depends on the specific AC voltage that the game will be operating with. Connecting the leads to the wrong taps can cause severe problems with the game electronics so they absolutely must be connected appropriately.

The North American standard for household AC line voltage is 110 VAC. In reality however, it is most common to measure something much closer to 120 VAC at any outlet. While operating at a slightly lower voltage will not harm the machine in any way, operating at a higher voltage (than the transformer is connected for) can cause the electronics, especially within the vector monitor, excessive and unnecessary stress and it can even lead to repeated failures of the deflection power transistors. If you are operating your game machine within North America, it is highly recommended that you change the connection of the transformer within your G80 game machine to use a 120 VAC winding.

I highly recommend that you download and read the following very informative document. It contains an excellent explanation of how and why to change the transformer connection as well as more useful tips.

Simple_Sega_G80_Vector_Mods.pdf by Patrick J. Cooke

 

( Click images to enlarge )

Factory shipped hookup: North America 110 VAC

 

Recommended hookup: North America 120 VAC

 

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