Question Adding mobo speed control (3rd wire) to Antec Tri Cool and 200mm Big Boy fans

[Biggerguy]

Decades long lurker, first time poster.

Excuse my 'behind the times' post, but I kind of enjoy making older hardware work in modern times. Case in point I just built a new system using all new old stock gear, with exception to a modern PSU and GPU.

I am recycling my Antec 900 Two case, it works, its massively overbuilt, and has copious cooling with fan filters. The problem with this case is that all the stock LED fans use 2 pin power and a speed selector switch that basically adds resistance to allow fan top spin at full or low speed. Its inefficient and just tedious, especially since my Asus Maximus VI Formula has excellent fan management. The proprietary Big Boy 200mm fan has no substitution. This is why I don't just swap everything out....and why toss out fans that still work perfectly and match.

As is it has been covered in at least two very oid posts,
https://forums.tomshardware.com/threads/mod-antec-tricool-case-fans.181559/ these the fans' PCB boards and microcontrollers actually have the functionality to monitor speed. They all contain hall effect sensors.

My question is can I just wire directly from the legs of one of these chips and plug into tach sensor pin on mobo fan connector? Or do I need diodes, resistors and such? I ask this because when looking at the traces, there is a path to wire this thing as the factory would have, but along these traces are spots for all the aforementioned components.
https://www.dropbox.com/scl/fi/gwwo...MP-2.jpg?rlkey=vbff4tglwkq2wdrhdm3fm5mqj&dl=0

Dropbox

www.dropbox.com

In the 2010 post referenced above they don't say if anything but a wire was added, it seems they just soldered on a wire and connected it to the mobo to monitor rpms and control fan speed via voltage regulation.

Also the microcontroller in the 120mm fan is FTC S277, from what I can tell the second leg from the left is where to solder a wire ?
https://datasheetspdf.com/datasheet/FS277.html

But on the 200mm Big Boy fan, things are a bit more complicated, there are several components. As far as i can tell the "brain" is an LB11967 chip from which I can tell from my very limited electrical abilities (none) has hall effect output. But I am not sure which leg is it, and again, would I be able to just solder a wire and plug it into the mobo? https://www.mouser.com/ProductDetail/onsemi/LB11967V-TLM-H?qs=5C9Q4QJFsuMFJ%2Bz9wibieA==

Dropbox

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https://www.dropbox.com/scl/fi/56nr...MP-2.jpg?rlkey=q93csu57rmnclju96fqpoevn9&dl=0



Lastly both these fans' pcb boards have an unused lug where the power wires go in labeled 'S", which I assume was intended as a speed signal output had the OEM specified it, and both those trace to the respective microcontrollers. Before taking them apart I tried simply soldering to the S lug on the Big Boy and nothing happened, after I tool it apart I saw the there were open connections along the trace, specifically labeled R9 and R

Thank you!!

 

[Biggerguy]

Decades long lurker, first time poster.

Excuse my 'behind the times' post, but I kind of enjoy making older hardware work in modern times. Case in point I just built a new system using all new old stock gear, with exception to a modern PSU and GPU.

I am recycling my Antec 900 Two case, it works, its massively overbuilt, and has copious cooling with fan filters. The problem with this case is that all the stock LED fans use 2 pin power and a speed selector switch that basically adds resistance to allow fan top spin at full or low speed. Its inefficient and just tedious, especially since my Asus Maximus VI Formula has excellent fan management. The proprietary Big Boy 200mm fan has no substitution. This is why I don't just swap everything out....and why toss out fans that still work perfectly and match.

As is it has been covered in at least two very oid posts,
https://forums.tomshardware.com/threads/mod-antec-tricool-case-fans.181559/ these the fans' PCB boards and microcontrollers actually have the functionality to monitor speed. They all contain hall effect sensors.

My question is can I just wire directly from the legs of one of these chips and plug into tach sensor pin on mobo fan connector? Or do I need diodes, resistors and such? I ask this because when looking at the traces, there is a path to wire this thing as the factory would have, but along these traces are spots for all the aforementioned components.
https://www.dropbox.com/scl/fi/gwwo...MP-2.jpg?rlkey=vbff4tglwkq2wdrhdm3fm5mqj&dl=0

PXL_20240201_183157716.MP~2.jpg​

Shared with Dropbox

www.dropbox.com


In the 2010 post referenced above they don't say if anything but a wire was added, it seems they just soldered on a wire and connected it to the mobo to monitor rpms and control fan speed via voltage regulation.

Also the microcontroller in the 120mm fan is FTC S277, from what I can tell the second leg from the left is where to solder a wire ?
https://datasheetspdf.com/datasheet/FS277.html

But on the 200mm Big Boy fan, things are a bit more complicated, there are several components. As far as i can tell the "brain" is an LB11967 chip from which I can tell from my very limited electrical abilities (none) has hall effect output. But I am not sure which leg is it, and again, would I be able to just solder a wire and plug it into the mobo? https://www.mouser.com/ProductDetail/onsemi/LB11967V-TLM-H?qs=5C9Q4QJFsuMFJ%2Bz9wibieA==

PXL_20240201_183020518.MP~2.jpg​

Shared with Dropbox

www.dropbox.com
https://www.dropbox.com/scl/fi/56nr...MP-2.jpg?rlkey=q93csu57rmnclju96fqpoevn9&dl=0



Lastly both these fans' pcb boards have an unused lug where the power wires go in labeled 'S", which I assume was intended as a speed signal output had the OEM specified it, and both those trace to the respective microcontrollers. Before taking them apart I tried simply soldering to the S lug on the Big Boy and nothing happened, after I tool it apart I saw the there were open connections along the trace, specifically labeled R9 and R

Thank you!!

 

[Paperdoc]

I see I participated in that thread from 2010, and I also contributed there some WRONG info. So let me help fix some of that.

We are dealing here only with the older 3-pin fan type - no relevance to 4-pin fans. In a 3-pin standard fan the three wires and their pins and wire colour codes are:
Pin 1 - BLACK - Ground
Pin 2 - RED - +VDC power supply
Pin 3 - YELLOW - speed pulse signal

Connector looks like this

Note how the two ridges on one side are - they go around the plastic "tongue" beside the mobo header's pins. In this pic the Pin #1 is at bottom left.

Control of the fan's speed is done solely by varying the VOLTAGE supplied to the fan by the header on Pin #2, from 12 VDC for full speed down to about 5 VDC for minimum speed without stalling. In my long post #14 of Oct 9/11, ignore the long second paragraph. It gives a detailed description of how fan speeds USED to be done, and that's not quite right for today. However, the stuff in following paragraphs is right. Note that you do NOT need the fan's speed signal sent back to the mobo header for speed control to work. The header ONLY uses that signal to show you the speed for interest, and to monitor for NO speed, meaning fan failure. If you do NOT send a speed signal to the header, most will allow you in the header configuration in BIOS Setup to ignore the fan speed or not send out any failure notice.

So, all you REALLY need to power AND control the speed of the fan is connections to the Ground (Pin 1) and +VDC (Pin 2) pins of the mobo header. But connect those to WHICH wire of the fan? This bumps into the other error in those old posts. On a standard 4-pin Molex power output from the PSU, the two middle wires are Black Ground. One end wire is RED and that is the +5 VDC line. The wire at the other end is YELLOW and that's +12 VDC. (In that 2010 thread the Red and Yellow labels were reversed.) So the fan's wire that MAY be red and is the +VDC power supply line should be connected to the YELLOW wire of the Molex connector when it is plugged in. That is the fan wire you want to get to Pin #2 of the mobo fan header. Actually, to get to having a standard 3-pin fan connector on the end of your Antec fan's wires, your easiest path might be to scavenge the wires and connector off an old dead fan and just splice the Red and Black onto your fan's wires.

Now, that still does not get your fan's speed signal to the header, which is what you asked about. Although you don't need it for control, you may want it anyway. I do NOT know exactly where in the fan's circuits you can tap into for the speed signal, but you have a bunch of that info from older sources. Do NOTE that any YELLOW wire you find inside the fan is NOT guaranteed to be the SPEED signal. Yellow IS the wire colour carrying the speed signal from a fully pre-wired 3-pin fan to the header, but that is NOT a universal convention.

I reiterate advice I gave back then. For the speed SWITCH included with that fan, simply set it to Full Speed and tape it up so you don't change it. This will remove any dropping resistors and have the fan run according to the Voltage supplied from the header.

If your mobo has only 3-pin fan headers there will be no confusion in using them. IF your mobo is like the most recent ones that has only 4-pin fan headers, almost all of those CAN be configured in BIOS Setup to act as 3-pin fans by setting them to VOLTAGE Control Mode (aka DC Mode) and NOT to PWM Mode. You CAN plug a 3-pin female fan connector into a 4-pin male mobo header only one way becasue of that ridge and tongue design, and it WILL work if the header is set to Voltage Control Mode.

 

[Biggerguy]

Thank you so much for the reply!

Yes, I understood what you wrote and have written prior.

I guess the bottom line to my query is given that all these fans generate a speed signal that is not being used for speed control and that the mobo needs this in order to regulate voltage/fan speed in a 3 pin fan, and having found the microprocessor that generates the hall effect signal, would I be able to just connect that without all the resistors etc that I see are missing on the traces that lead to what would be the factory connection point labeled S, which as it is now S terminates along those traces due to the missing aforementioned components?

My greatest fear is not ruining the fan, but burning out something on the brand new old stock and thus no warrantee mobo.

This is the chip of the Big Boy. The leg I think I have to tap into is the one labled FG, following traces from it leads to S, but as mentioned missing resistors and continuity along the way
https://html.alldatasheet.com/html-pdf/439590/SANYO/LB11967V/465/3/LB11967V.html

This is the ubiquitous chip on the 120mm fan, which I beleive is still used on today's modern fans. Pretty sure the leg to tap into is #2 labeled NO. Looking at another fan I have that has functional speed monitoring, the FTC chip second leg goes to another chip with three legs labeled 5342 Y525, then from there to S. So I really dont know.
https://datasheetspdf.com/datasheet/FS277.html

 

[Paperdoc]

You misses a bit of my last post. The mobo does NOT need the fan's speed signal in order to control it. It does not even use that for control. Control is based ONLY on the TEMPERATURE from a sensor on the mobo. The system adjusts the Voltage sent to the fan according to the temp reading.

The header DOES count the pulses arriving from a fan;s speed signal. it can display that speed for you for your interest. It also monitors that in case the fan fails and there is NO signal. A failure will produce a warning pop up on your screen. So it there is no speed signal delivered to the header you will get that warning, but usually the BIOS Setup options for a header allow you to disable that. The header does not actually NEED the speed signal if YOU don't need to see it or to be warned of fan failure.

I do not know how to figure out where to tap into the signal on the motor's board. Others here may be able to advise. IF you know where that signal is, I doubt very much that any form of it from the motor can damage the mobo fan control circuit. My concern instead would be whether tapping into that signal at some point might load the motor board's circuit enough to distort or reduce the signal so the board's normal processes are disturbed. My GUESS is that this signal, generated by a Hall Effect sensor, is used in that board's system to synchronize the switching of power supply to motor windings with rotor position. This is the solid-state switching system that replaces the older commutator system in classic DC motors, yielding the brushless DC motor.

 

[Biggerguy]

Thanks again
No I fully understood what you wrote. What I am saying is the mobo has 4 pin fan connections. As you stated I can choose the 3 pin orientation, and I can even connect a 2 pin fan. But unless the board sees the speed, it will jut run the fan at full speed relying on the physical switch for me to manually change it's speed, which is exactly what I do not want.

 

[Paperdoc]

Ah, now I see why you pursue this. The dilemma is that the mobo control of fan speed still does NOT use the speed signal for its work. Further, UNlike the new PWM style 4-pin fans, the ones you have are 3-pin fans with NO internal chip to use the PWM signal from a header to alter fan speed.

For a 3-pin fan the ONLY way to control its speed is to supply it from the header with the correct VOLTAGE from Pin #2. It can range from 12 VDC full speed to 5 VDC for minimum speed.

The question is how to achieve that on your mobo, and it is not clear from the manual. On the CPU_FAN header (see manual p. 3-42) the text says basically in default mode the header will use PWM Mode which cannot control a 3-pin fan. BUT is says IF you are using a 3-pin fan then you select Advance Mode. Unfortunately this option is NOT detailed for the CHA_FAN headers that you would use for case ventilation fans p. 3-43). What it does say is that for each of those 3 headers if you select the Manual Profile then you can specify the lower and upper points of the "fan curve" graph of fan speed versus temperature measured by the mobo sensor. It does NOT say this will then do this using the older Voltage Control Mode instead of the new PWM Mode. Bu that is possible, since that is what one option for CPU_FAN does. It is ALSO possible - NO guarantee, just a guess - that this older board is using a small "cheat" from the early days of PWM fan systems. The new fans are designed so that, if you connect a 4-pin fan to a header using only the older 3-pin fan Voltage Control Mode with no PWM signal, they still WILL have their speed controlled in this system. So some early mobos used ONLY the Voltage Control Mode on CHA_FAN headers and relied on this, assuming that no user would figure out that PWM was not actually in use. IF that's what your mobo is designed for, those CHA_FAN headers CAN control the 3-pin fan. You could test for this if you have a spare real 3-pin fan. Just plug it into such a header, try this configuration through BIOS Setup and see if the fan speed can be controlled, or always runs full speed.

If that does not work, next option. Your mobo has three CPU_OPT headers. Normally such would be controlled using the temp sensor inside the CPU chip and not the one on the mobo, so it is not ideal for case ventiation fans. BUT it could be used. Then the question is whether setting the CPU_FAN header to 3-pin mode by choosing the Advance Mode option there ALSO will set the CPU_OPT headers the same way. Again, you can test with a spare 3-pin fan.

If that does not work, a third thing to look for. On more recent mobos there is an option in most fan headers to select whether the header uses the older 3-pin Voltage Control Mode (aka DC Mode) or the newer PWM Mode. There is NO mention of this in your mobo's manual. But the mobo utilities disk contains AI Suite 3, a utility that runs as an app under Windows so you can adjust mobo items without using BIOS Setup. It includes Fan Xpert 2, a software tool for adjusting fan performance. Look through that in case it contains such an option for the CHA_FAN headers.

To reiterate, ability to control the speed of your older 3-pin fan type does NOT require that the fan's speed signal be sent to the host header of the mobo. It DOES require that the header be configured to use the older Voltage Control Mode and not the newer PWM Mode. So even if you bought a new 3-pin fan instead of converting your older Antec unit, you still have this requirement.

 

[Biggerguy]

I really appreciate you taking the time to try and help me.

I can confirm that with an old 3 pin fan, Antec sent me 2 newer fans back in the day under warranty (maybe from the V.3 of this case that has some slight electrical modernizations), that has 3 pin power in addition to a knob for infinite speed adjustability. In the case of those fans, I simply turn the knob to max, connect the power wire with 3 female connections to the male 4 pin fan header, and Ai Suit 3 can see and modulate the fan speed using its software. Additionally, I have another fan, that is a new and modern 4 pin and it is fully controlled by Ai Suite's FanXpert2 software as well. So either type will work. But FanXpert2 will only modulate the fan's speed when it has an RPM signal, otherwise its full speed ahead!

 

[Paperdoc]

You say, "But FanXpert2 will only modulate the fan's speed when it has an RPM signal, otherwise its full speed ahead!" Are you sure about that? That is quite UNcommon in fan control systems. NOTE this factor in your testing. You are using a 4-pin header of the mobo. You report that, when you plug into that a spare 3-pin fan, it CAN alter the fan speed. It also can do speed control of a 4-pin fan. So in at least one of these tests (maybe both) it is using the older Voltage Control Mode. But the header MAY be able to change which MODE it is using. IF you plug a 3-pin fan into a header using the new PWM Mode, that fan will run full speed - no control. But you do not seem to get control of one fan when you use the FAN Xpert2 software tool. WHICH FAN IS TROUBLE? Within that tool when you plug in a 3-pin fan, look closely for a choice to set the MODE and ensure it IS using Voltage Control Mode (aka DC Mode). Without that setting the fan will always run full speed.

By the way, how do you now it will not control without a speed signal? Have you been able to connect the old Antec fan you are trying to modify to the mobo 4-pin fan header for a test? IF that is what you have tried, FIRST test out the header using Fan Xpert2 and the spare 3-pin fan, making sure the header is in Voltage Control Mode and does control its speed. The without shutting down, unplug that spare and plug in the old fan-to-be-modified. Check Fan Xpert2 again to be sure it is still using Voltage Control Mode. Can speed be controlled by Fan Xpert2 this way?

 

[Biggerguy]

Great news,.mission accomplished!

Thanks largely to the info by member Fruc , who actually responded to a pm from me, it's now working.

The fan had no way to be controlled by FanXpert without the speed signal. But as you and others have said all these fans have a speed signal by design, it's just whether or the OEM decides to make the data available externally.

I was able to tap into the Big Boy's brain and get the speed signal now it works perfectly. The crazy thing is that it's literally all there, just need circuit completion, why Antec didn't do this is beyond me.

I decided to make a video to help others.

Thanks again!

View: https://youtu.be/9IpnhchCt4M?si=Sqvc4Kg4VoFCrB7m

 

[Paperdoc]

Glad to hear you got it done! Your research paid off. I congratulate you on sharing the results for others to use!

I think what Antec did with these fans (I had a couple in an Antec case years ago that I really liked) is design them solely to be powered by a fixed 12 VDC supply from a 4-pin Molex PSU output, including a three-speed manual switch to give users some means to reduce speed and noise. The never intended them to be connected to a mobo header and controlled that way. So speed signal access was not a need, nor was there any way to send it anywhere when the fan's only connector went to the 4-pin Molex. Other makers have produced similar fans with TWO connectors on their cables, one of which was the standard 3-pin fan connector. But those designs did not include the three-speed manual switch, so with them the only way to get speed control was to choose the mobo header connection option.