Sinclair ZX Spectrum

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
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6.4 Video Incorrect .................................................................................................................................. 32
6.4.1 Dark Screen ................................................................................................................................ 32
6.4.2 Dim ‘Sinclair’ logo....................................................................................................................... 32
6.4.3 Wavy lines across screen ........................................................................................................... 32
6.4.4 Self-resetting .............................................................................................................................. 32
6.4.5 Random dynamic squares .......................................................................................................... 32
Paper area too low .............................................................................................................................. 32
6.4.6 Diagonal lines in the border area ............................................................................................... 32
6.4.7 Distorted video ........................................................................................................................... 33
6.5 Colour tuning faults (Issue 1 and Issue 2 boards) ............................................................................. 33
6.5.1 Initial check ................................................................................................................................ 33
6.5.2 VR1 or VR2 fails to adjust IC14 pin 13 waveform ...................................................................... 33
6.5.3 VR1 or VR2 DC shifts IC14 pin 13 waveform .............................................................................. 33
6.5.4 Alternate dark lines on screen ................................................................................................... 33
6.5.5 No colour after trimming TC2: ................................................................................................... 33
6.6 Colour Faults (Issue 1 - Issue 3 boards) ............................................................................................. 34
6.6.1 Pin screen ................................................................................................................................... 34
6.6.2 Blue haze around `Sinclair` logo................................................................................................. 34
6.6.3 Screen too yellow ....................................................................................................................... 34
6.6.4 Intermittent colour .................................................................................................................... 34
6.6.5 Red, Blue or Green `Sinclair` logo .............................................................................................. 34
6.6.6 Washed out colours ................................................................................................................... 34
6.7 Keyboard Faults ................................................................................................................................ 34
6.7.1 KB1 fault ..................................................................................................................................... 34
6.7.2 KB2 fault ..................................................................................................................................... 34
6.7.3 Dead keyboard ........................................................................................................................... 34
6.7.4 Wrong keyboard response ......................................................................................................... 34
6.7.5 Keyboard response too fast ....................................................................................................... 34
6.8 Regulator Coil .................................................................................................................................... 34
6.8.1 Coil excessively noisy ................................................................................................................. 34
6.9 Speaker ............................................................................................................................................. 35
6.9.1 No speaker output ..................................................................................................................... 35
6.10 Speaker Load Input Waveforms ...................................................................................................... 35