The custom Sinclair chip responsible for video, sound, and tape I/O. If this dies, the system often displays a dead black or white screen.
Pinpointing intermittent RAM faults that only appear after the computer warms up. How to Load and Run Test Programs
The story of the Spectrum continues with modern recreations like the . These systems come with their own specialized test applications. These tools verify the functionality of their modern features, such as SD card transfer buses and enhanced video modes, helping to ensure all hardware components are working as expected.
Original ZX Spectrum 16K/48K, with added tests for 128K models. zx spectrum test program link
If the screen is black or unstable, the ULA chip is likely dead.
4. Step-by-Step Troubleshooting Checklist Using Test Software
For issues related to loading from cassettes, is a system software program that focuses on the tape loading mechanism. It can help visualize and debug problems with the cassette interface. The custom Sinclair chip responsible for video, sound,
A is the first step in restoring a dead Speccy to life. By using a diagnostic ROM like Phil Ruston's DiagROM, you can quickly move from a black screen to knowing exactly which component needs replacing.
Precise RAM bit-failure identification, ULA timing, keyboard matrix integrity, and sound (AY-3-8912) chips.
Search GitHub for "brendan alford zx spectrum diagnostics". You will find the open-source repository containing the latest compiled .rom files. How to Load and Run Test Programs The
A failure at any point outputs a specific memory address and failing bit pattern, often via a binary-coded border color or a simple text output on a working screen.
On a 48K Spectrum, if the test program flags "Bit 0" as failed in the lower 16K region, you know exactly which physical chip to desolder (IC6 on most board issues).
If your test program says , focus on the lower bank (IC15-IC18 on Issue 3 boards).