[N8VEM: 16931] parportprop video dim?

[Jim Strickland]

I have a question about my parportprop board on my zeta. I had assumed that
its somewhat dim performance on my LCD was because it wasn't driving the
LCD at its native frequency. To that end, I got my hands on a Sony
multisync trinitron over the holiday and hooked it up. I got the same dim
output. I have also tested the monitor with a PC vga board and gotten
normal bright colors, so my question is, are others seeing this?

Looking at the VGA spec, I see that my initial hypothesis that a 3.3v
propeller can't generate the 5 volt signals for the vga standard is
rubbish. The vga spec is 0.7v p-p. I am now wondering if my substitution of
slightly higher resistances in the last stage of the DAC resistors is
what's biting me. I've not tested the output voltages, so it could be
something else entirely. Suggestions?

-JRS

[p***@public.gmane.org]

Hi Jim,

The 0.7V level is when the signal line is loaded with at least 1x 75ohm
load (and lots of implementations double-terminate the line with 2x 75ohm
loads at both sides of the cable for better signal quality).

Are you measuring these levels when loaded with the actual monitor?

Regards,
picmaster


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