.:madworm:.'s photos
quadrature decoder: algorithm
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quadrature encoder: 4 state machine
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quadrature encoder: calculate phase angle
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Closeup on the encoder mechanics
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It works with magnetic proximity switches in a quadrature encoder setup. The mechanical parts were built by our machine shop. Great people !
Sega Game Gear fixed sound
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A piece of art. 20 years old. The video output is also somewhat blurred. I've read it can be fixed by replacing a whole lot of other caps, but as I don't really play with it anymore it's not necessary (yet).
sega gamegear backside
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The top middle screw is some kind of security bolt. Once you've managed to get it out, DON'T put it back. Keep it as a token of victory!
Sega Game Gear fixed caps
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The old caps must have dried. I replaced them with some 45µF ones I could find. The internal speaker works again (middle cap). The other one is for the 2nd channel which I haven't tested yet. No earphones at hand.
Sega Game Gear fixed C5
Sega Game Gear fixed C7
Sega Game Gear security bolt
TDA2822M test circuit
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Audio amplifier used in Sega Gamegear. The 470µF caps were changed to 47µF on the gamegear's sound-ampifier PCB and they went bad (C=0,R>>1). Therefore no current and thus no sound anymore. The other electrolytic caps may be bad as well, but they don't seem that critical. The small caps are SMD parts and still work (most likely ceramic or whatever).
Sega Game Gear soundcard
Sega Game Gear soundcard
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This is the corpus delicti. At least that's what I hope. The TDA2822M is just a dual amplifier. It gets 2V supply voltage from the main PCB and about +-100mV sound signal. If that's OK must still be checked. The datasheet gives a minimum of 2V as supply.
Sega Game Gear soundcard
Sega Game Gear soundcard
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Sega Game Gear powersupply
Sega Game Gear
Sega Game Gear soundcard
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