Sinclair Research ZX Spectrum - Page 38

AREA SYMPTOM ACTION
Video Incorrect. Dark Screen. 1. Check tuning.
2. Change modulator.
Dim 'Sinclair' Io9°- 1' Check +12V"
2. Check C65 for high
impedance.
3. Check R52.
4. Check +5V on IC14 pin 3.
Wavy lines across 1. Press down on each
screen. electrolytic capacitor to
see if lines disappear.
If so change that
capacitor.
2. Check crystal X2.
3. Check/change TR1 and/or
TR2.
4. Check/change IC14.
Self resetting. Check TR6.
Random dynamic Change C54.
squares.
Paper area too low. Change IC1.
Diagonal lines in Change R47.
the border area.
Distorted video. 1. Check for +3V at IC1
pin 13.
2. Change C30.
Colour tuning - Visually check IC14 circuits.
faults (Issue 1
and Issue 2 boards)
VR1 or VR2 fails to 1. Monitor IC14 pin 2
adjust IC14 pin 13 trimming VR2.
waveform. 2. Monitor IC14 pin 4
trimming VR1.
3. Change IC14.