Lian-Li Front Case Fans

[NSN]

I am posting this here since I am certain that many of you are using
Lian-Li cases.

My question is about the two front fans. These are 3 wire fans
connected to a small 3 switch circuit board with resistors that
controls the speed of both fans. My understanding on fan speed control
in general, is that by varying the voltage to the red fan lead
(usually connected to the yellow 12V Molex) one controls the speed,
The third wire, in general, (blue or yellow) is used for speed
monitoring, not for speed control.

However, the Lian-Li front fans are 3 wire and all are connected to
the small circuit board. There is no fan speed monitoring that I can
determine. My questions are:
1. How is the speed controlled in the Lian-Li ... by varying
voltage or by some other method using that third wire??
2. Are these special fans with the third wire (blue) set up to
control speed rather than monitor speed?

Norm

 

[Paul]

I am posting this here since I am certain that many of you are using
Lian-Li cases.

My question is about the two front fans. These are 3 wire fans
connected to a small 3 switch circuit board with resistors that
controls the speed of both fans. My understanding on fan speed control
in general, is that by varying the voltage to the red fan lead
(usually connected to the yellow 12V Molex) one controls the speed,
The third wire, in general, (blue or yellow) is used for speed
monitoring, not for speed control.

However, the Lian-Li front fans are 3 wire and all are connected to
the small circuit board. There is no fan speed monitoring that I can
determine. My questions are:
1. How is the speed controlled in the Lian-Li ... by varying
voltage or by some other method using that third wire??
2. Are these special fans with the third wire (blue) set up to
control speed rather than monitor speed?

Norm

I haven't a clue, but I'll contribute a couple of pictures:

http://www.7volts.com/bb2.jpg
http://www.7volts.com/cllbrfm.jpg

The pictures are from http://www.7volts.com/lian_li_case.htm

The controller board has a three position switch and what
looks like two power resistors. In high speed, I would bet
the red wire is connected directly to yellow (+12V). The
medium speed, causes the current to flow through one resistor.
The slow speed causes the current to flow through two resistors.
You can verify this, by using an ohmmeter, and measuring from
yellow to red, with the disk drive power connector disconnected
from the power supply. To get to the red signal, disconnect one
fan and touch the middle pin on the header on the controller
board. The ohmmeter would read 0 ohms, then R1 ohms, then
R1+R2 ohms, so the value you read should be increasing as you
move the switch through the H,M,L positions respectively.

It _looks_ like a simple resistive voltage reduction technique.

The blue could be tacho, but I have no way of verifying that
for you. I'd try to look up info on the fan, but I don't
recognize that logo (is it trying to say "Adda" ?).

You could unscrew the controller board, and examine it, to see
if any connection is being made to the blue wire. If the blue
wire is a no_connect, then at least you know it is not a fan
control signal of some sort. But, I wouldn't take chances, and
would try to track down info on the fan manufacturer. There
are some fans that deliver a "locked rotor" signal, instead of
tacho, on the third wire (like some Panaflo fans), and I
don't think it hurts to connect one of those to a normal
fan header. I would do my homework first, if possible.

HTH,
Paul

 

[Roger Hamlett]

I am posting this here since I am certain that many of you are using
Lian-Li cases.

My question is about the two front fans. These are 3 wire fans
connected to a small 3 switch circuit board with resistors that
controls the speed of both fans. My understanding on fan speed control
in general, is that by varying the voltage to the red fan lead
(usually connected to the yellow 12V Molex) one controls the speed,
The third wire, in general, (blue or yellow) is used for speed
monitoring, not for speed control.

However, the Lian-Li front fans are 3 wire and all are connected to
the small circuit board. There is no fan speed monitoring that I can
determine. My questions are:
1. How is the speed controlled in the Lian-Li ... by varying
voltage or by some other method using that third wire??
2. Are these special fans with the third wire (blue) set up to
control speed rather than monitor speed?

By using the third wire. However your basic 'premise', that using the
third wire for a tacho, is 'standard', is flawed. This is only really
'standard', in the PC marketplace. In normal use, there are a lot more
varieties. As an example, I have a fan catalogue here. Out of fifty
different basic 'types' (each of which then comes in different sizes, and
speeds), only two have the tacho wire, while five have the third wire used
for speed control. Of these, two use a thermistor on the line to vary a
current and control the speed, one uses a DC voltage to vary the speed,
one accepts a serial command, and the last one implements a bi-directional
serial control/reading link, which allows the speed to b read, and the fan
controlled with just one wire...
The Lian-Li fans are probably standard speed controlled fans, but they
might well use either a varying voltage, or a current change to actually
control the units.

Best Wishes

 

[NSN]

Paul & Roger:

Thanks .. you have answered my questions !! If a fan ever goes bad I
will pull the little circuit board and check the schematics. I just
went over to the ADDA web site and indeed, they have numerous
configurations for that third wire .. one being speed control. I
suspect that rather than directly changing voltage to the fan, the
resistors are connected to the signal reaching the third wire and
controlling the speed in that fashion.

http://www.addausa.com/options/options-index.html

Norm

 

[NSN]

I decoded the model number of the fan via the code sheet on the ADDA
site. AD0812MS-A76GL.

The above means that the fan is 12V DC brushless in aluminum frame
with sleeve bearing, 7 blades. The third wire is dual function:
protects motor via transistor and is also a speed sensor. Thus, those
two resistors do directly regulate the voltage.

Norm