Component Mod question (Screen flash)

[thesteve]

The composite jack uses a 75ohm to ground and 470uf cap to jack

[NightWolve]

You talking about the TV's Composite input jack, that there's a filtering cap there too besides the 75 Ohm grounding standard ?

I'm guessing you are cause I noticed that Hudson didn't design any amp ciricuit with a filter capacitor at the end unlike say the SNES which uses 200 uF for Luma/Y and Composite.

This: http://www.pcenginefx.com/forums/index.php?topic=9150.0

[thesteve]

No, I am referring to the duo
The 470uf cap behind the power switch is your composite coupling cap
Has a 75ohm grounding resistor before it

[NightWolve]

Ah OK, so you are suggesting a cap possibly for the Luma/Y in your circuit to help for this. Looks like Bonknuts' circuit dump is missing components that are supposed to be there too, then! Seems the service manual for the tg-16 doesn't show this cap either...

[thesteve]

Yep

[thesteve]

Jus added a new schematic to the old thread
It should address all issues that have been brought up, including wider application

[NightWolve]

Alright steve, yay, you did it already! So you went with 470 uF I see. I liked that better because I noticed that there was 0 DC offset build up when you disconnected the signal and left a DMM on it. With a 220 uF on a SNES, the DC keeps going up and up and up until you connect it up and it discharges back down to 0. With 470 uF, nothing. I wondered though how that affects the video signals. Regardless, since Hudson chose 470 uF (albeit with the additional Chroma signal component), I guess if it was good enough for them, good enough for us in modding applications. I'll update the first post with the schematic.

[thesteve]

Just spotted an error on update