Zenith PRO 895x/900x

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This board has four diagnostic lights on it that can assist in troubleshooting.

The top light is the standby light, and should be on whenever the set has power. The H drive light indicates that horizontal drive is present on this board. The H drive feeds the horizontal output board. The H drive light simply means that the drive signal is present. A fault in the H output board can mean that the H section is still problematic.

The V drive light is similar to the H drive light. This RGB board also sends the V drive signal to the V output board.

The video enable light comes on only after the H and V drive signals and high voltage to the tubes are confirmed. It is possible for all four of these lights to be on and another fault in the set will cause a ‘no picture’ symptom, but many ‘no picture’ faults can be traced to this board. If any of these four lights are not on, chances are this board is bad.

This board also holds the EPROM and memory chips, but these have proven to be quite reliable in the past.