Can I "mod" a 2-wire fan so the RPMs can be changed?

[Winey]

I have some Panaflo L1A fans with two wires coming out of the hub of
the fan, but the wire connector has the space for the third wire.
Presumably that is for the fan speed wire.

This may be a really silly question, but can I "mod" the fans by
adding the third wire and fixing the connector?

Somehow it seems so obvious.

 

[Sonic]

If you want to change the fan speed, just add a resistor into the circuit.
If you want to monitor the rpm, you'll need the third wire.

 

[Paul]

I have some Panaflo L1A fans with two wires coming out of the hub of
the fan, but the wire connector has the space for the third wire.
Presumably that is for the fan speed wire.

This may be a really silly question, but can I "mod" the fans by
adding the third wire and fixing the connector?

Somehow it seems so obvious.

This outfit sells Panaflo stuff. Type "Panaflo" in the search box.

http://www.bigfootcomputers.com/Merchant2/merchant.mv?Screen=SRCH&Store_Code=Bigfoot

I don't know why this fan has so many options. You would think if the
fan truly has the tachometer signal on it, the fan could sell
for more money, so why would you ever sell it with just the
two wire interface ? It doesn't make a lot of sense. A better
plan would be for Panasonic to make a cheaper fan with only two
pins on it, like the rest of the cheap case fans. Then, they
could charge more for a three pin version with tachometer.

Since the three pin cable assembly is backordered on that site,
you can make your own. I found some three pin connectors, suitable
for plugging onto the motherboard header, at my local electronics
store. You simply push the wire into a compression fit "fork"
on the end of connector, so no solder is required. I found solder
_was_ necessary, to keep the wire from escaping, if there is any
stress and strain on it, when the fan connector is inserted or
removed.

Info on the fans is here:

http://www.panasonic.com/industrial/appliance/appliance_fans_panaflo_axial.htm

It is possible your fan is FBA08A.

Notice how they call the third pin a "locked rotor alarm sensor, 2PPR".
Thank goodness the 2PPR was tacked on there, as that means two pulses
per revolution, which is the definition of a tachometer output. So,
the third pin does look like it will work, once you get a three pin cable
and some wire.

Hmmm.

I just searched in the Digikey catalog, and a different picture is
emerging. Download this page:

http://dkc3.digikey.com/PDF/T042/1225.pdf

It appears the fan part number can end in AZ, BS, BX, BO, and S
(according to the key at the bottom of the table of fans). I
guess that means a plain and simple L1A, has no options, and
the third pin is window dressing.

A (no option, as in L1A ?)
AZ - Solid housing
BS - Locked Rotor Alarm Sensor (not a tacho output)
BX - 2 PPR Speed Sensor (yes, that _is_ the desirable tachometer output)
BO - Same as AZ+BS
S - Same as BS

So, put the soldering iron away :-(
The Digikey info suggests you would have to buy a medium speed 80mm
fan, to get tacho output, like the FBA08A12M1BX for $8.75

Paul

 

[P2B]

I have some Panaflo L1A fans with two wires coming out of the hub of
the fan, but the wire connector has the space for the third wire.
Presumably that is for the fan speed wire.

This may be a really silly question, but can I "mod" the fans by
adding the third wire and fixing the connector?

Somehow it seems so obvious.

No problem, instructions here:

http://tipperlinne.com/fan-tach.htm

HTH

P2B

 

[Dorothy Bradbury]

In short...
o No
o The signal on that pin is Locked-Rotor (1A) and not Tacho signal (1BX)
---- Not commonly readable on PCs
---- Commonly readable/used/required on Apple/SUN/SGI/DEC-Alpha
o Only a few Panaflo are available with 1BX option code
---- 60mm in H noise-spec, 80mm in M noise-spec, 120mm in H noise-spec
---- 92mm in L noise-spec
o The 1BX option code uses a different PCB & motor-ic
---- the 1A motor-ic is generally slightly quieter for silence-addicts
-------- it uses soft-edged microprocessor switching for low-noise
---- the 1BX motor-ic has the caveat of higher switching noise evident
-------- however some applications will not run without a tacho signal

Tacho signal on tier-1 fans is somewhat moot - the fan has an L10 figure,
field-data confirmed, that exceeds the typical life of the equipment it goes in.


In full...
o Panasonic Panaflo part numbers describe the actual specs of the fan
---- same for all fan makers, just a matter of knowing how they work
o Note that OEM (integrated into product) codes may differ
---- codes may be the OEM codes, or equivalent field-replaceable units
---- odd sizes are possible, eg, 70mm, 100mm, 110mm but very rare

For 60-120mm fans, taking FBA08A12L1A:
o FBA = Non-Augmented Flow Tubeaxial Fan (ie, not FBL, FBK, FBZ)
o 08A = 80x80x25mm, 08T = 80x80x15mm etc
o 12 = 12V DC, 24 = 24V DC
o L = Low Noise Spec (M H U are available, OEM can use others)
---- eventually you will see an S spec below L, but not for some time
o 1A = option code
---- 1A = Locked-Rotor Signal on 3rd "S" marked pin
-------- 1BS, 1J, 1AZ, 1BO similarly don't provide tacho output
-------- 1AZ is 1A with solid corners for more rigid blade-to-housing gap
---- 1BX = Tacho-RPM Signal on 3rd "S" marked pin
-------- 1CX is available, but relatively uncommon

The 40mm Panaflo don't have commonly have such option codes.

For Papst the tacho signal is designated by a /2 on the fan model code
o Example, an 8412NGML in tacho-signal form is 8412NGML/2
o Only a few Papst fans are provided with the signal at retail level
o Note than OEM options are broad, such as /9, /14 codes
---- so connect only a /2 fan to a PC - other codes are not compatible

For NMB the tacho signal is designated by TWO option codes
o Taking NMB 3110KL-04W-B10-A00, the last TWO codes matter
---- B10 is your noise level AND an option code
---- A00 is another option code
o For tacho signal, BOTH the B code & A code are modified
---- the B code gets a 9 added, the A code must be 50-100
---- So NMB 3110KL-04W-B19-A49 is NOT tacho
---- So NMB 3110KL-04W-B19-A99 IS with tacho signal
o Other option codes are possible in the B option code
---- B66, B16, B23 etc
---- typically these are OEM spec fans & noise-level may vary

For example, Dell use a B66 spec fan & B86 fan on their topline
Dimension computers - both have extremely high airflow figures.
Dell implements a remote temperature control system - so allowing
the same fan to be fitted in the PC be it in non-HVAC Saudi or in
freezing North Pole environments, the speed simply adapts.

Eventually such temp variation will be dropped as it has time latency,
thermal latency, hysterisis and often poor matching = acoustic noise.
Instead the fan speed will be regulated to current draw via either the
CPU, or current supply via the PSU - so instant response. That
avoids the common problem of a macro noise/thermal solution from
a temp-controlled fan still having some areas running hot either when
tested as a physical prototype or thermal CFD model in Flotherm.

Tier-1 makers are generally integration - and so design options to suit.
NMB do about 200M, >45% of the global market, with only a very
small number going into retail which is a disliked channel as availability
of replacement options there disintermediates out silly overpriced spares
from manufacturers. Sometimes proprietarisation can be used to stop
a substitute fan, either at simple level (Apple reverse the pins) or more
complex level (custom 2-speed control & feedback with no-boot).
Dec Alpha's will not boot without a 1A signal fan re "fan turning".

Tacho fans are often available only on specific models, and NMB in
general don't have any tacho models available to retail. You can order
them, but it's pay up-front, 16-26wk waiting period subject to JIT
factory scheduling, and min orders quantities which can be 50k units.

That's for tier-1 fan makers, lower tiers choose different segments and
may put OEM tacho models out into retail distribution more often. Most
makers only make a tiny fraction of their available range (eg, ADDA have
a simply vast range but only make a tiny part of it). Others, like EBM-Papst
offer a very large range of fan sizes - and make all of them, but only a few
are available with tacho signal. Depends on the market demands re economics.

Eventually the tier-1 fans will be programmable - you choose what you want
by non-contact programming or signal down a lead (like AMD program their
XPs according to requirements or yield capability). That is in the future, EBM-Papst
are likely to be the first although NMB may offer it first. I doubt it will be available
to end-users, it may be for distributor profit/convenience/availability instead. So
for end-users there would be a benefit, as well as to their ears.

 

[P2B]

In short...
o No

Meaning my solution won't work on a Panaflo fan?

http://tipperlinne.com/fan-tach.htm

Why not?

P2B

 

[Winey]

Thanks to everyone who responded. I now know far more about the
varieties of Panasonic fans than I ever imagined existed. I
downloaded and saved off some good stuff for future reference.

I read the URL below. I guess it's feasible to add tacho out
capabilities to any fan, but I'm not sure it's worth it for a guy like
me who hasn't really used a soldering iron since the days of punch
cards and the original IBM Series/360 mainframes. (before the 370s
and virtual memory, even!)

So, I guess the short answer is that if I need fan monitoring, e.g.
for heat sinks, I go out and buy some new fans. For case fans, I'm
sure these are fine.

 

[Dorothy Bradbury]

Meaning my solution won't work on a Panaflo fan?

http://tipperlinne.com/fan-tach.htm
Why not?

No, see my followup further up the thread

My comment was re the "S" signal pin on 1A fans is a signal,
but is a locked-rotor signal and not a tacho rpm signal (1BX).

 

[Barry Watzman]

No, the 3rd wire is for a "tach" signal, it is simply the fan reporting
it's speed. It's not for actual control of speed, which is done simply
by changing the DC voltage on the existing two wires. No mod required.

 

[Overlord]

In response to the question in the title; why?
If the fan is connected to the mb, it's unlikely the mb is actively
using the rpm monitoring wire to control the fan speed since the
actual efffectiveness of fans varies widely with the speed.
The mb is already controlling the speed of the fan by varying the
power to the fan header depending on the temps.

I have some Panaflo L1A fans with two wires coming out of the hub of
the fan, but the wire connector has the space for the third wire.
Presumably that is for the fan speed wire.

This may be a really silly question, but can I "mod" the fans by
adding the third wire and fixing the connector?

Somehow it seems so obvious.

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[Keith S.]

What MB are you using? I used SpeedFan to control the fan speeds (even
shuting them down) on a Asus P3b-f.
http://www.almico.com/speedfan.php