Sinclair ZX Spectrum Service Manual

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

Sinclair ZX Spectrum Specifications

General

Processor	Zilog Z80A
Clock Speed	3.5 MHz
RAM	16KB or 48KB
ROM	16KB
Graphics	256 x 192 resolution
Sound	1-channel beeper
Storage	Cassette tape
Input	Keyboard
Power	9V DC
Release Year	1982
Display	TV via RF modulator
Ports	Expansion, RF
Colors	15 (8 colours with two levels of brightness each, plus black)