Editing Sinclair ZX Spectrum +2 Troubleshooting Guide (section)

== If it does not initialise ==

With the rails and clocks proven, the 128 manual's sequence is:<ref name="sm128" />

# Check +5 V and ground distribution to the ROM, Z80, ULA and RAM.
# Check '''RD, WR, MREQ, D0–D7 and A0–A15''' from the Z80 — all should be active immediately after a reset.
# Check the '''RAS/CAS lines to the uncontended RAM area''' (IC15–IC22 in 128 numbering) — active immediately after reset.
# Check the '''RAS/CAS lines to the contended RAM area''' (IC6–IC13 in 128 numbering). Press the RESET button to obtain a clear trace.
# Confirm the '''ROM is enabled''' by an active-low signal at pin 20.
# Check the '''bank register''' is loaded correctly — immediately after reset, pins 2, 5, 7, 10, 12 and 15 should be low.
# Check the outputs on the RGB connector.