Problem with Sunbeam Rheobus. 12V line drops to 11.5V and makes LED fans dim. Possible mod to fix the LED's?

[KYDave]

I made a post about this in the main hardware forum, but it would be down on page 6 in less than a day so I'm giving up on it, hehe.

I recently built a new PC and added a Sunbeam Rheobus to control my case fans. I'm trying to control 4 Cooler Master Blue LED fans. I love the fans, but when I hook them into the rheobus the LED's are noticably dimmer. I checked the voltages and here's whats happening. The 12V line coming off my PSU and MB are all about 11.96V, including the line going INTO the rheobus. But the line coming off the back of the rheobus to power the fans is only 11.50V with the knobs turned all the way up.

Is there any sort of mod I can make to the rheobus to get a full 12V out at max power?

After getting no replies on my other thread and then thinking about it a bit I figured it might be a better idea to just mod my fans so the power for the LED's comes from a constant source instead of the rheobus anyways. THis way I can turn down the power on them and not loose the brightness at any level. From what I can tell the 4 LED's are all in series with each other with just under 12V going to them when 11.96V is applied to the fan. This gives about 2.9x V over each LED so I'm assuming no resistors were added in series to drop the voltage. I tried to find info about the fans to see what type of LED's were in them but I can't find that info anywhere. What I was thinking of doing was cut the line running to the first LED and just apply 11.96V from the MB or the PSU. I'm hoping this doesn't fry the LED's, but we'll see.

Anybody got any experience doing anything like this? Or any ideas on how to get more voltage out of the rheobus?

Thanks in advance,
Dave

 

[mastay]

First, by specification, manufactures are given at least 5% wiggle room. That is, a sytem promising to output 12V can legally do anywhere from 11.4-12.6. Second, anything that consumes power acts like a resistors. Having LED in series with each other involves having the 1st acting as a resistor to the 2nd, which both acts as resistor to the third... Maybe try a parallel connection instead?