Someone help me set up old-school voltage fan control

salmonmeat

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May 8, 2017
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Hey guys, I'm hoping for some help here. I bought a super ghetto case from my local shop for twenty bucks, and I've been scratching my head trying to figure out how the previous owner had the fans set up.

the front panel has some weird analog dials which are supposed to show the case temp, fan speed, and "HDD" (speed?). coming out of the bottom of the front panel, there are various connectors: a 2-pin "HDD LED" daisychain/passthrough, what I assume is the thermometer, a male 3-pin, and a female 3-pin:

o61Jsh4.jpg


the case fans have only 4-pin molex connectors, and also included was a 3-pin male to molex adapter:

p859gM6.jpg


So, help me understand what's going on here. One possibility is that the front panel acts as a fan controller and automatically adjusts the voltage that it passes to the case fans based on its temperature reading.

Another possibility is that the front panel is supposed to connect to one of the 3/4-pin fan connectors on the motherboard.

In either case, I think i'm in need of a female-to-female 3 pin, maybe another 3-pin to molex adapter.

Anyone here have some knowledge on how these work? thanks in advance!

 
Solution
That Molex to 3-pin adapter will destroy a fan. The TACH signal is connected to +5V, and that will destroy the open-collector outputs on most fans.

Regarding what's doing what, I'd need to see a circuit diagram. This is very clearly slapped together without a care for what the connectors are normally used for.
That Molex to 3-pin adapter will destroy a fan. The TACH signal is connected to +5V, and that will destroy the open-collector outputs on most fans.

Regarding what's doing what, I'd need to see a circuit diagram. This is very clearly slapped together without a care for what the connectors are normally used for.
 
Solution