I have always had a huge fascination with electronics, but never the time to devote to learning it beyond a couple of quick tutorials here and there (and the basics you learn in school). So, sorry if this is too dumb a question for this forum, but here goes anyway.
I have a (SATA) harddrive caddy which I use for backups and moving these from one computer to another. It works well but is notorious for using bad (ie, loud and pretty useless) fans. The device is currently connected so I cannot check, but I believe the fan is 5V (I doubt it is 12V, but it is possible). I can disconnect this fan, and the device works fine, but it causes one of the LED indicators at the front to remain on.. which is also pretty annoying (it's the same LED used to signal when the disc is being accessed, so if it is always on, that renders this function useless too).
But this got me thinking, "what if I just connect an equivalent resistor there instead of the fan? This might mean I can remove the fan, and the noise, and not have that LED permanently lit up." So, am I thinking correctly here? I have a multimeter, so I can check the resistance of the fan, and find a resistor of the same resistance. Would this work? And, what should I have in mind when trying to do this? Thanks in advance.
Edit:
A few of the answers have been asking this, so I thought I would just clarify that this is a 2-wire fan. I don't want to replace the fan, I just want to know (also out of curiosity and to learn more about electronics) if this is possible (which, given some of the answers, it looks like it is) and how to go about doing this (safely).
In case anyone is curious, this is the item: KingWin SATA Aluminum Mobile Rack with Single Fan, KF-811-BK
Best Answer
If the fault detection depends on current variation with rotation, the resistor isn't going to fool it at all. After all, current will not drop if the fan stalls with dog hair, but air flow will, so simply detecting the current is about useless for detecting fan failure (and is seldom used). Tachometer fans have an extra lead for this purpose, but it can be achieved without extra bits.
You could probably make an oscillator circuit to fool it that would be close enough, but it might be easier to search out the controller and disable it or just replace the fan with a quiet one.
For an example of a current detecting controller, the Microchip TC64x series uses a current sense resistor on the low side:
I would suggest replacing the fan.. the rule of thumb is every ten degrees C of heating halves the life of the product.