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I am a hobbyist and recently acquired a dead Gameboy that I am going to attempt to repair. My first thought is to clean up the damage from leaking caps and batteries and replace the caps. I was trying to understand it a little better and happened upon the following schematic, however I am not sure what the X means at certain wire junctions. I am thinking it means it is not connected?

Further, the power switch has a strange wire symbol that curves up to a white rectangle. Not entirely sure if this is supposed to be a thermistor or something else?

Gameboy DMG-1 power schematic

enter image description here

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    \$\begingroup\$ the X is not at a junction between two wires ... the rectangle that surrounds the transformer circuit is not a wire \$\endgroup\$
    – jsotola
    Apr 11 '20 at 3:22
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The X means it's some kind of connection to a connector pin or between two modules. It is definitely connected, otherwise the thing would not work.

The power connector includes a switch that disconnects and reconnects batteries based on if the DC plug is inserted. The rectangle is most likely supposed to represent the big center pin of the DC socket.

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In this case, the X is there to let you know that there is no wire connection. If you study the schematic in your link, you will see that each place where there is an "X" one of the lines is NOT a wire. It is a part of a box or dividing line that has been put in place for organizational or documentation purposes.

I would rather see it be a dashed or dotted line, personally. Or in this day and age, simply have the non-wire lines be a different color from the wire lines. But this is probably an old schematic.

I think the white rectangle you are talking about is the place where you plug in the power supply. I think it is trying to show you that the power supply socket has a built-in switch, and that the internal batteries are disconnected when you plug in an external power supply. This prevents you from trying to charge the internal batteries when you plug in the supply. The logic is not clear from the diagram (looks almost opposite) but that would make no sense. It has to disconnect upon insertion, logically.

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    \$\begingroup\$ Oh that makes so much sense... the module line looked like a wire and really confused me. Thanks! \$\endgroup\$ Apr 10 '20 at 23:24
  • \$\begingroup\$ The other answer is also right. The X's show where a straight wire goes through a boundary. That would be another way to say it. The main point is that the module or board separations lines look exactly like wires, and the X is there to help you realize that those boundaries are NOT a wire. \$\endgroup\$
    – mkeith
    Apr 11 '20 at 5:04
  • \$\begingroup\$ I might as well add that it is considered bad form to connect wires in a 4 way cross (4 wires all meeting at a single point). It is OK for wires to cross if they are NOT connected. But if they ARE connected, then one of them should be offset so it is not a 4-way cross. HOpe that makes sense. \$\endgroup\$
    – mkeith
    Apr 11 '20 at 5:09

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