ATI 4850/4870 voltmod thread

[celemine1Gig]

I would recommend either 2 200k potentiometers connected in series (resulting resistance of 400k), or alternatively a single 500k (or at least! a 200k) potentiometer. Keep in mind that the latter will have less precision in lower resistance (=higher voltage) ranges.
Anything less, concerning the total resistance, would give too much of a default voltage bump IMHO.

Set (all) the potentiometer(s) to their/its max. resistance and connect them/it bewteen pin#19 and pin#14. That should work. Maybe you got a black screen because you hit the OVP voltage limit. Then you could consider yourself lucky.

BTW: What the heck does that mean "50 h vr"?

And another thing:

celemine1Gig ...messured resistance between
pin 1 - 19 = 10.06 k...

I'm sorry, if this sounds rude, but do you even remotely know what you are doing?
Why would you want to measure resistancee between pin#1 and pin#19, which correspond to "EN" and "Vfb"? What do you think has the "Enable" pin to do with the feedback in terms of a vmod.

EN Pull this pin high to enable controller. Pull this pin low to disable controller. Either an open−collector output
(with a pull−up resistor) or a logic gate (CMOS or totem−pole output) may be used to drive this pin. A Low to
High transition on this pin will initiate a soft start. If the Enable function is not required, this pin should be tied
directly to VREF.