CPD1604S Vertical Collapse

[vol.2]

Originally Posted by Alex KL-1

The bright pin have a fixed divider. Perhaps the IC have a pedestal clamp, independent of the fact of it being clamped at the CRT? Perhaps it have, for having more defined levels to the vide out.
So, *perhaps* altering the bright pin voltage the pedestal will alter. Is worth investigating.

Thanks. This does seem to agree with what I have seen. I get a better picture and more total contrast if I crank up the brightness knob on the front and I turn down the G2.

Probably the best solution is to build a -100V power supply and pull the G1 negative, but I don't have the parts for that right now. I am thinking about trying it though.

In the intervening time, I managed to tweak the resistors on the TE pins and eke more contrast out of the VPS10 IC. I now have it to about the same level of brightness as the VPS07T, but it's much, much crisper and there isn't any red smearing anymore like the VPS07T had.

Totally worth it.