Replacing a dual pwm fan with a single
- Thread starter Fritz
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It really depends on the value of the bus resistors used for pull-up on the rpm signal lines, but generally yes, it should be ok. Only drive the fan from a single fan PWM supply though, leave the other open 
OK, original ganged fans 2 4 pin on one plug.
First fan is Blue, Yellow, Black,Red
Second fan is Orange, Gray, White, Green
I'm assuming that yellow is the tach wire for fan one. Since the gray wire is opposite the yellow in the plug, can I assume it is the tach wire for the second fan?
I can't find the second fan color code anywhere.
First fan is Blue, Yellow, Black,Red
Second fan is Orange, Gray, White, Green
I'm assuming that yellow is the tach wire for fan one. Since the gray wire is opposite the yellow in the plug, can I assume it is the tach wire for the second fan?
I can't find the second fan color code anywhere.
Normally for a standard 4 wire fan that follows the spec, it would be Black = Gnd, Yellow = +12V, Blue = PWM, Green = Tach.
Of course the Chinese are a law unto themselves, so it's likely Black = Gnd, Red = +12v, Blue = PWM, Yellow = Tach. I would imagine in a double header arrangement, that the wiring is mirrored from one side of the header to the other, making in your case, White = GND, Green = 12+, Orange = PWM, Grey = Tach. PRetty much all these small fan controllers have polarity protection and most modern mainboards have current limiting on the connectors, so no harm should come of giving it a try
Of course the Chinese are a law unto themselves, so it's likely Black = Gnd, Red = +12v, Blue = PWM, Yellow = Tach. I would imagine in a double header arrangement, that the wiring is mirrored from one side of the header to the other, making in your case, White = GND, Green = 12+, Orange = PWM, Grey = Tach. PRetty much all these small fan controllers have polarity protection and most modern mainboards have current limiting on the connectors, so no harm should come of giving it a try
BTW: This is a Gnodal GS 4008, a.k.a Boeing 747 noise simulator, I'm working on. The original fans were unbearably loud. I replaced them with Supermicro FAN-0061L4's. The switch functions normally (fans at max during boot then slow down) and temp is fine (25c). The only issue is the switch is reporting all 3 fans as non operational. They're all spinning and temps are good so I'll just ignore it. Even tho the SM fans are not the quietest they are hella quieter than the original fans. It was no freaking fun wiring them in but when all is said and done, I'm happy with the results. The switch is back in the rack where it belongs and you can no longer hear it from outside the house.
The fan is being controlled to, at least, some extent? What manufacturer/ model fan is the original?
It's quite possibly a simple fix, if you had some way of testing the Tach output. A logic probe/ scope or similar will definitely tell you if the Tach is going low enough. Eiether way, you need a good solid pulse train otherwise the board will freak out. By paralleling the Tach inputs, you are effectively halving the pull up resistor value, the fan o/c output may not be able to pull it low enough to be recognised as valid, for example
It's quite possibly a simple fix, if you had some way of testing the Tach output. A logic probe/ scope or similar will definitely tell you if the Tach is going low enough. Eiether way, you need a good solid pulse train otherwise the board will freak out. By paralleling the Tach inputs, you are effectively halving the pull up resistor value, the fan o/c output may not be able to pull it low enough to be recognised as valid, for example