Sinclair ZX Spectrum Service Manual

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
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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.

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)