Sinclair ZX Spectrum

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
31
6.2 NO VIDEO
6.2.1 No video
Change IC1
Check TR1 and TR2
6.2.2 No video after ULA changed
Visually check IC1 and socket
Check for shorting between C65 and R53
Carry out Power Supply Unit check
6.2.3 No +5V input
Check voltage drop across R64
Check +5V regulator O/P and +9V regulator I/P
Check PWR socket not shorted
Check power unit
6.2.4 No VIDEO INPUT at IC14 pin 12
Check waveform at IC14 pin 13. If correct check TR1 and TR2
Check waveforms at IC1 pins 15, 16 and 17
If correct check VR1, VR2 (Issue 1 and Issue 2 boards)
Change IC1
If +5V and Video Input correct, change modulator.