Sinclair ZX Spectrum Service Manual

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
30
6 FAULT DIAGNOSIS AND REPAIR – INPUT/OUTPUT
TV screen dead, smoke appears on switch-on / Not Initializing
No Video
Corrupt Paper, after ULA change
Video Incorrect
Colour Tuning Faults (Issue 1 and Issue 2 boards)
Colour Faults (Issue 1 - Issue 3 boards)
Keyboard Faults
Regulator Coil
Speaker
Speaker Load Input Waveforms
6.1 TV SCREEN DEAD, SMOKE APPEARS ON SWITCH-ON / NOT INITIALISING
6.1.1 TR4 base-collector shorted:
Remove TR4
6.1.2 Short persists with TR4 removed
Check TR5 and C44
Visually check track
Check TR4
6.1.3 TR4 blows again
Change TR4 and TR5 (even though TR5 checks out)
Check the TR5 circuit components are to latest specification

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)