Editing Sinclair ZX Spectrum+ Troubleshooting Guide (section)

== Video and colour faults ==

* '''No colour.''' On Issue 2, adjust TC2, VR1 and VR2 first. On other issues, change the '''LM1889 (IC14)''' — though it is a very reliable part. Some later boards were fitted with an '''SN-series device in the IC14 position, and this was always the cause of no colour'''; it should be replaced with an LM1889, which the board still has provision to accept despite the different pin count.<ref name="ian" /><ref name="sm48" />
* '''No video input at IC14 pin 12''' — check the waveform at IC14 pin 13; if correct, check TR1 and TR2. Check the waveforms at IC1 pins 15, 16 and 17; if correct, check VR1 and VR2 on Issue 1 and 2 boards. Then change IC1. If +5 V and video input are both correct, change the modulator.<ref name="sm48" />
* '''Dark screen''' — check tuning, then change the modulator.<ref name="sm48" />
* '''Dim Sinclair logo''' — check +12 V, check C65 for high impedance, check R52, and check +5 V on IC14 pin 3.<ref name="sm48" />
* '''Corrupt paper after a ULA change''' — check the ULA socket, check the power socket is not intermittent, and check IC1 pin 14 for +5 V with no discernible ripple.<ref name="sm48" />
* '''No 3 MHz at IC2 pin 6''' — if the amplitude is low check R25; check TR3; check IC1 pin 32 for 3 MHz and IC1 pin 39 for 14 MHz; check crystal X1; check IC1 pin 13 for +3 V.<ref name="sm48" />
* '''Wavy lines across the screen''' — press down on each electrolytic capacitor in turn and see whether the lines disappear; if so, that capacitor is the culprit.<ref name="sm48" />