We have a circuit that uses the adv7393 as the encoder for an ntsc output. However, we're having trouble getting the output to meet brightness and contrast expectations with our customer.
We have a 7180 on the input and have the lines tied to the 7393 in this scenario. We used a black to white bar tpg and plugged it directly into the TV, then plugged it into our board. When the signal goes through the 7180 and out the 7393 we get significant loss of brightness and contrast. We tried playing with luma adjustments, brightness, DAC voltage gains adjustments in the 7393, but we could never get the white as bright as when the tpg is fed directly into the screen.
Do you have any suggestions on tests we can run, or things to look at and compare on the analog side of the signal?
Is there anything in the circuit, pcb, or cabling that can cause this kind of degradation?