HIKVISION DS7208HVI-ST Product/Maintenance Manual page 15

②. No VOUT Output
Step 1: measurement HK-5 (TVS9) whether short circuit, or replacement
Step 2: measuring 75Ωresistance (RS117) impedence, or replacement
Step 3: monitor's signal lines connected to the probe, directly from SGM9111
(US7) chip PIN 4 draw out the VOUT signal, or replacement
Step 4: measuring 75Ω resistance (RS188), or replacement, and then monitor's
signal lines connected to the probe, directly lead CVBS -VOUT signal
from 75Ω resistance (RS188) end, or KY2010 ruled out
③. Image Problem
Phenomenon 1: there is no video signal, first exclude HK-5 (TVS1-8) whether
short circuit, or replacement; Measuring 75Ω(RV1-8) resistance, or
replacement, and then ruled out 100Ωresistance (RU1-8); Finally ruled out
TW2866 (can directly introduce video signal into TW2866 chip video input
end,PIN13/17/21/25, to rule out the chip is normal or not)
Phenomenon 2: a few channel image black screen, first rule out the software
settings, otherwise introduce video signal into TW2866 chip video input end,PIN
13/ 17/21/25, to rule out the chip is normal, or replacement
Phenomenon 3: all black and white images or flower screen, to rule out 27 M
(Y4/Y5), then rule out software, or change TW2866
④. Voice Problems
Phenomenon 1: preview no voice, first without software Settings, then
measuring 100 resistance (RS46) and capacitance (CS18) impedance, or
replacement, finally ruled out TW2866 (US1) (can directly introduce audio
signal into TW2866 chip audio input PIN 6, to rule out the chip is normal or not)
Phenomenon 2: voice talkback AOUT no output, measuring 3.9 K resistance
(RS60) + 390Ωresistance (RP24) resistance, or replacement, finally ruled out
TW2866 (US1) (directly lead AOUT signal from the TW2866 chip PIN2, to
exclude the chip is normal or not)