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Sync on Green Capacitor Replacements
Robert Neumann edited this page Dec 10, 2018
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Sync pulses for the RGBS and the Component inputs are AC coupled to the 5725 scaler IC.
The GBS8200 design (all variants I know of) does not follow the datasheet for the coupling capacitors.
The value for "C33" and "C35" should be 1nF (1000pF), but the installed capacitors have a value of 100nF.
Due to the high capacitance, the SOG extraction circuit in the 5725 sees too much of any eventual video content, instead of just the synchronization pulses.
This leads to frequent short sync losses when the picture content changes rapidly, for example on a flashing screen.
The issue can be resolved by replacing C33 and C35 with correct value parts.