Sonic Invader - no power repair

This vintage handheld came in dead, no power. In average condition.

Diagnosis

Opened up the case, found battery leakage. What a surprise.

The damage stemmed from the battery negative end all the way to the mainboard.

Some under the VFD display too.

And the VFD display must be desoldered before I can find a cause.

Turns out the return path of the switching transistor has no continuity to GND.

This was the place actually broken.

But for the sake of longevity, there are a lot more trace to be repaired. All have solder mask damaged.

This one alone can revive the handheld already. More to go.

Trace fixes and more trace fixes.

Both the buzzer and battery wires became fragile after 40+ years. Replaced with silicon insulated wires.

Fixed.