Summary

Late model 240p/480i television with composite, s-video and component inputs.

Manuals

• User Manual
• Service Manual

Notes

Composite 240p Performance, Disabling Vertical Edge Enhancement

by Eli Krause

I. For composite decoding this set uses a Toshiba TC90A53N, a 3-line digital comb filter. One beneficial feature of this comb filter is its "1-line color dot interference reducer circuit". Depending on the console/revision, dot artifacting ranges from slight to moderate, and blending effects may be broken. Using an external notch filter to decode composite instead^[1] (such as is available in a RetroTink scaler) and sending that to the component input would blend all dithering patterns and remove nearly all dot artifacts.

II. Just as velocity scan modulation is intended to increase contrast at horizontal edges, vertical edge enhancement artifically boosts contrast at vertical edge transitions for composite and RF sources. To reduce this to its minimum, the high signal sent to pin 17 of the comb filter must be brought low which can be achieved by removing the resistor leading to that pin. On the AV-20D202 and AV-27D302 it is R239 on the bottom of the main board. On the AV-32D502 it is R247.