Click of death

The picture's juming is caused by the video sync being disabled during the short reset periods.

The "Click of Death" is the name given to a fault which can occur on cartridge systems, most often MVS boards.

The system fails to start, while a periodic click/pop sound (sample) can be heard in the audio, if the amplifier or TV volume is set loud enough.

Cause

The particular sound is a side effect caused by the system resetting itself (see watchdog) and causing the YM2610 to output sudden voltage changes on its analog output.

The periodicity means that the system tries to boot over and over.

Investigation

The repetition rate of the click can give clues about the actual fault.

• A fast click (~8Hz) often means that something essential doesn't work: no clock to the 68k, cut or shorted bus, dead work RAM, dead CPU, dead system ROM, can't write to NEO-B1...
• A slow click (1Hz or less) can mean that some step of the system self-test causes a crash. Address lines, dead memory, shorted traces...
• Random clicks can indicate cut, floating traces.