Visit worldofspectrum.org or spectrumcomputing.co.uk and look in the utilities section for "Test Tape" or "Diagnostic".
Disk (TRD/DSK/SCL)
Here is the direct link to the pre-assembled 16K ROM binary: zx spectrum test program link
Finding a working is the first step in bringing your classic computer back to life.
Excellent alternative repositories for downloading diagnostic tape images. Visit worldofspectrum
: Checking the functionality of the "dead-flesh" rubber keyboard and attached peripherals like joysticks.
For fully functional machines that exhibit intermittent stability issues, the original factory test tapes (or their digital .tap / .tzx equivalents) can be loaded normally. They walk the user through screen alignment, color fidelity, and tape head azimuth calibration. : Checking the functionality of the "dead-flesh" rubber
Tell me which you’d prefer (assembler source, TAP/TZX creation script, or a packaged test-suite layout) and target machine (48K, 128K, +3, or a specific clone).