Editing Sinclair ZX Spectrum +2 Troubleshooting Guide (section)

== Audio hum and buzzing — a known +2 fault ==

A distinctive and very common complaint on the grey +2:

'''Taiwanese-built +2s suffer from poor grounding, which produces buzzing or humming on the audio output.''' Because the audio output is live even when the Datacorder is not running, the hum is present all the time.

The cause is that the '''tape deck PCB uses the metal frame of the tape mechanism to route ground paths between different parts of the board'''. The fix is straightforward: check that the '''two screws fixing the tape PCB to the mechanism are tight and making a good electrical connection'''. Tightening or cleaning them usually cures it completely.<ref name="sfe2">Spectrum for Everyone, [https://www.spectrumforeveryone.com/technical/servicing-2s-datacorder/ "Servicing your +2's Datacorder"]. Source for the grounding-related audio hum and its fix, and for Datacorder servicing practice.</ref>

Separately, the AY-to-beeper mix is poorly balanced on all 128-family machines, so ULA sounds being much louder than AY music is '''normal behaviour, not a fault'''.<ref name="tyne" />