Is it ok to put a pump on a rheostat?

Revivalist · Nov 28, 2005

My pump (the mcp655) has an adjuster on it but I don't want to have to open my case every time I need to adjust it. I would like to just put it on a rheostate with a knob that sticks out the back of my case. But I wasn't sure if messing with the input voltage could harm the pump (since I know that adjusting the knob on the pump itself doesn't actually change the input voltage so it's not the same thing as an external rheostat.)

Pro*Banshee · Nov 28, 2005

Make sure it's rated for the wattage you want. those little radioshack jobbies wont cut it

Revivalist · Nov 28, 2005

Pro*Banshee said:
Make sure it's rated for the wattage you want. those little radioshack jobbies wont cut it

Thanks. I forgot to consider the current that it has to take. The MCP655 does about 2A. I don't think I'll find a rheostat that fits in a PCI slot and can handle that current. Oh well. :shrug:

Aidenswarrior · Nov 28, 2005

i was also thinking about this idea. I would also like to know

sumka · Nov 29, 2005

I don't have a D5 (yet) but if I did I'd consider opening it up to find out what the speed adjuster on the pump actually is, to see if it's something like a 10K potentiometer or something, and if so consider running an external POT wired to the D5's circuit board (in the same way some fans have an external speed-adjust on a cable).

This might be a better method if it's the case as it would do the same task as the original speed controller, rather than trying to limit the pumps speed by current/voltage (just a theory).

ƒÓÒl · Nov 29, 2005

You don't have to go that far, since it's already wired inline with the pump's feed wiring, just hook up a multimeter and turn the dial from one extreme to the other to get it's range. You'll likely get a reading with it turned to zero (resistance from the windings), so you'll have to do some math.
If it's a pwm instead of a VR, you may not get much change in the reading.

Personally, instead of risking a warranty on a pump that expensive, I'd look into using a rod to extend the existing knob to the back or front panel...

Revivalist · Nov 29, 2005

ƒÓÒl said:
You don't have to go that far, since it's already wired inline with the pump's feed wiring, just hook up a multimeter and turn the dial from one extreme to the other to get it's range. You'll likely get a reading with it turned to zero (resistance from the windings), so you'll have to do some math.
If it's a pwm instead of a VR, you may not get much change in the reading.

Personally, instead of risking a warranty on a pump that expensive, I'd look into using a rod to extend the existing knob to the back or front panel...

The knob on the pump requires a tiny screw driver. I think making a stable post for it that reaches all the way out of the case would be really difficult.

Is it ok to put a pump on a rheostat?

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