Zalman MFC1 7V mod
 

greetings everyone. just a quick question... i have a Zalman fan controller as stated above. i use the 4 variable channels for case fans and the 2 5V/12V for my water cooling radiator fans. now then, what i'd like to do is turn the 5V/12V into a 7V/12V since at 5V, one of my 120mm sunon fans won't even run, and my antec 120mm really doesn't pull enough air. has anyone, done a mod like this? if so, how? if not, it makes sense to me to get a multimeter and try to find and switch out a resistor or two to try and bring the 5V up to 7V. i assume that with a little V=IR, i can muster something up. any comments? thanks again......

You won't be able to run the 5 volt up to 7, with a simple resistor: the 5 volt line comes directly from the power supply.

7 volts is achieved in the difference between the 5 volt line, and the 12 volt line (12 - 5 = 7, see?). You might be able to mod your circuit to do this, but you would have to know what you'r doing, otherwise you might end up shorting the 5 volt line from your PSU (and you'll burn something in your controller).

Why don't you just use the 7 volt trick directly on that fan? It won't be adjustable, but it'll work. Alternatively, you can make a switch yourself that does this (want a diagram?).

hmm, guess i never thought about the 5V line. good point, thanks. :D really, what i wanted was the 12V for heavy computing applications, and the 7V for idle. i wonder if i can somehow just have the 12V run for both switch positions and add a resistor inline to reduce the voltage to 7. i'll have to take the controller out to look at it more carefully. however, that means the computer is offline as well. hmm. i suppose we'll see if i have some time to work it out this week.

If you're going to do that, you might as well put together the rheostat mod (Google). Otherwise, wire (and install) a switch to change the voltage from 7 to 12 volts, if you can't adapt it to your circuit.

You know what you're looking for, right? ;)

yeah, thanks. i appreciate it. i'll see what i can do. if i can't modify what i need, then prehaps it's time to invest in a new controller.