exxos's Atari, Amiga & retro forum

The caps are helping, the black is now darker and the green more pronounced, so definitely an improvement on the non cap picture.

PhilC wrote: 12 Dec 2019 19:47 The caps are helping, the black is now darker and the green more pronounced, so definitely an improvement on the non cap picture.

Wonder how this all works on the Falcon then as those caps are "missing" on there as well.. unless I missed them somewhere..

Definitely the caps are not there on the Falcon
:shrug:

I only know that myself and @Icky Tried bridging the caps and it made no difference for us...I thought they are supposed to be there as they were in the DAC datasheet, but as we found no change by bridging the caps, and not used on the Falcon, I did not bother to fit them on the H4.

Though I wonder if this only affects the VGA port and not the RGB ?

exxos wrote: 12 Dec 2019 19:59

Though I wonder if this only affects the VGA port and not the RGB ?

I use my two NEC monitors for everything and usually I have to adjust the brightness to full when using your via adaptor but this is with the monitor set to default but auto contrast. So about 50% brightness and contrast.

I don't have the second board built yet to try it with the normal rgb. Maybe someone else can verify that?

PhilC wrote: 12 Dec 2019 20:18 I don't have the second board built yet to try it with the normal rgb. Maybe someone else can verify that?

Yeah someone must be using RGB, I think everyone mentions its to bright ?

The only difference I can see in the two circuits, other than the caps is the voltage dividers but now knowing the falcon circuit I have no idea where R G & B go to, as we are using the RCON, GCON and BCON. should we be using the RGB instead?

PhilC wrote: 12 Dec 2019 20:30 The only difference I can see in the two circuits, other than the caps is the voltage dividers but now knowing the falcon circuit I have no idea where R G & B go to, as we are using the RCON, GCON and BCON. should we be using the RGB instead?

RCON, GCON and BCON is the RGB output, the other lines (voltage dividers) goto the RF stuff.

@exxos, @PhilC - I am using RGB with SCART, this is where I am seeing the complete whiteout on one of my monitors / TV (see pic)

I'll give the resistor and caps ago (when I get time) to see how that changes things.

@Icky try just the resistors first as it's the easiest and made the most difference for me. Might be that we still need to go higher than 150ohm?

@PhilC what voltage do you get (on scope) on the RGB lines on the connector ?


On the pdf...


So there is a 1.685 DC offset when we have "black". so max is 3.315 - 1.685 = 1.63V... VGA apparently is supposed to have 0.7V max, so we double the input voltage right there.

Its possible the Videl doesn't output a MSB input to the DAC. Will try and scope it tomorrow.