Sinclair ZX Spectrum

Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
36
7 FAULT DIAGNOSIS AND REPAIR – COLOUR, REPAIR AND UPGRADES
IC14 (LM1889) Pin Signals
Repair
16k to 48k Upgrade
Integrated Circuits/Link Settings
Issue 2 Board
Issue 3 Board
7.1 IC14 (LM1889) PIN SIGNALS
Pin No.
Signal
1
(Chroma lead) Sinewave 500mV, 0.2us, DC 9.5V
2
(R-Y Input)
3
(Chroma Bias) 4.8V DC
4
(B-Y Input)
5
(Ground) 0V
12
(Video input) DC 12V unregulated
13
(Chroma subcarrier)
14
(RF Supply)
15
(Sound tank) ‘Linked’ 12V DC
16
(Chroma supply)
17
(Chroma oscillator output) Square wave 0.2us 4V p-p 0.8V DC
18
(Chroma lag) Sine wave 500mV p-p 2us 9.5V DC
6,7,8,9,10,11
Not connected