On Sat, 23 Mar 2013 10:48:27 +0000, Clive
wrote:

In message
,
" writes
Instead of just a simple
fan motor, it's a fan that's variable speed, driven by a PWM
signal.
If by PWM you mean pulse width modulation, then it would allow for
variable speed, but a DC motor is an inductive load and is not sensibly
controlled by such a system unless there is something in the circuit to
allow the peak voltage generated by the motor at pulse cut of to be
shunted to earth.
PWM is the most common method of controlling the speed of DC motors -
a flywheel diode is part of the "system" to handle the inductive
kick-back. Virtually all battery operated variable speed power tools
use PWM. So do virtually all electric bicycles with brush motors and
the vast majority of electric forklifts.

In fact, just about any application of a brush type DC motor that
requires reasonable speed control has switched to PWM control of some
sort over the last 20 years, including power wheel chairs (except
those using 3 phase brushless motors)

jim beam wrote:

it means that, if you know what you're looking at, a dvm can tell you
most of what you need to know here.


Sure it can, if you're nothing more than a low grade grease monkey.


fact check required


Your checks always bounce.

--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

wrote:

On Fri, 22 Mar 2013 04:31:00 +0000 (UTC), Bimmer Owner
wrote:

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

That's an interesting idea.
http://www3.picturepush.com/photo/a/...g/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult


Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

Bimmer Owner wrote:

On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:

If it's being blown by intermittent high current draws the
fuse could protect the $100 FSU.

That's an interesting idea. The FSU supposedly consumes the
most power when the blower motor is set to the LOW settings
(simply because it has to dissipate the power as heat), so,
we could prevent excess current by fusing... say with a 10A
fuse, the blower motor (which is said to consume 5 to 6 A).


It should generate less heat at low speeds, if it is PWM.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

On Sat, 23 Mar 2013 22:27:41 -0400, "Michael A. Terrell"
wrote:


wrote:

On Fri, 22 Mar 2013 04:31:00 +0000 (UTC), Bimmer Owner
wrote:

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

That's an interesting idea.
http://www3.picturepush.com/photo/a/...g/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult


Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.
Or just get the special tester that is made to plug into the
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.

tm wrote:

"Bimmer Owner" wrote in message
...
On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:

If it's being blown by intermittent high current draws the
fuse could protect the $100 FSU.

That's an interesting idea. The FSU supposedly consumes the
most power when the blower motor is set to the LOW settings
(simply because it has to dissipate the power as heat), so,
we could prevent excess current by fusing... say with a 10A
fuse, the blower motor (which is said to consume 5 to 6 A).


Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.


I've seen 20W power resistors in TO-220 packages.


PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

Another place you could measure the current is by putting an ammeter in
place of the blower motor fuse.

tm


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

wrote:

On Sat, 23 Mar 2013 22:27:41 -0400, "Michael A. Terrell"
wrote:


wrote:

On Fri, 22 Mar 2013 04:31:00 +0000 (UTC), Bimmer Owner
wrote:

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

That's an interesting idea.
http://www3.picturepush.com/photo/a/...g/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult


Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.
Or just get the special tester that is made to plug into the
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.


Is that cheaper than roll your own?


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

Michael A. Terrell wrote:
tm wrote:


Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.

I've seen 20W power resistors in TO-220 packages.

It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).

But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.

PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.

If it's a RoHS soldering issue, though, I would not be surprised.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:
Michael A. Terrell wrote:

tm wrote:


Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.

I've seen 20W power resistors in TO-220 packages.


It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).

But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.


PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.


This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.

If it's a RoHS soldering issue, though, I would not be surprised.
--scott

A few car manufacturers use resistor wire in the harness leading to
the motor connection at the blower box.

This lowers the Q significantly giving you a voltage drop of course,
but it also reduces electrical noise and helps suppress the wheeling
voltages.

Blower motors in this case are normally designed to operate lets say
8 volts for example, for full RPM.

I learned this years ago when going through the pain of removing the
blower in an air box of a Chrysler product, only to find there was
nothing wrong with the motor. Symptoms led on to the fact there was
since the output of the speed control circuit was alive and happy but
no obvious connection to the motor. If I had unplugged it from the air
box before pulling that all apart, I would of noticed it.

The problem was the resistor wire in the harness which had open at the
crimp point, also in the harness.

Jamie

On 03/20/2013 09:13 PM, jim beam wrote:
On 03/20/2013 08:08 PM, Bimmer Owner wrote:
Does anyone have insight into what is the root cause (and repair) of the
FSU failure that plagues almost every 1997 to 2003 BMW?

http://www.bimmerfest.com/forums/att...0&d=1194115994


Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The "blower motor resistor", which also goes by FSR (Final Stage
Resistor)
or by FSU (Final Stage Unit), is known to fry itself in almost every
single
E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
http://www.bimmerfest.com/forums/sho...d.php?t=143393

The problem with replacing this ~$100 part is that the new replacement
FSU
fries itself just as often as the old one did, so you end up repeatedly
replacing your fried FSU every few years or so.
http://www.bimmerfest.com/forums/sho...d.php?t=528566

That's fine for most people (although the DIY is a PITA) - but I ask
this newsgroup whether anyone has any insight into WHAT is actually
breaking - and - why?
http://www.bimmerfest.com/forums/sho...d.php?t=309399

Here is the best (admittedly sketchy) wiring diagram we have so far:
http://www1.picturepush.com/photo/a/...g/12467819.png


that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.



old resistor packs for fans were open wire that sat in the fan's air
stream for cooling. they were generally very reliable if their alloy
wasn't too susceptible to salt.

that unit looks like it still sits in the air stream with that honking
great heat sink and i estimate it's trying to dissipate 100W. that can
only mean it's a linear controller because a modern pwm device can
control high motor currents with very little heat dissipation 10W.

bottom line, a linear controller is always going to get hot and end up
frying itself over time. the only thing you can do is either replace it
with another unit that will ultimately meet the same fate, or undertake
a significant modification.

for the latter, you can try putting an even bigger heat sink on it - but
i doubt there's a lot extra room available. you can also "pwm" it. i
built a similar unit to deal with a linear controller over-heat issue on
my 89 civic.

http://www.flickr.com/photos/38636024@N00/5068043855
http://arduino.cc/en/Tutorial/PWM

depending on how much time you want to spend on a project like that, pwm
can control superbly and offers benefits like motor speed not being so
susceptible to supply voltage [engine idle voltage drop] etc.

the down side of pwm is that it can generate electrical noise. [poor
stereo installations can be particularly susceptible.] the ideal
solution is to implement pwm with "soft switching", but that's getting
quite advanced.




--
fact check required

that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

I see many Motor Speed Control Manufacturers upped their PWM
frequency to be between 16 K to 22 K to eliminate much of the noise.
Mikek

"amdx" wrote in message
...
that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

that doesn't of course get around the fact that the unit in question here
is apparently badly under rated, but the above does at least explain why
it's used.

I see many Motor Speed Control Manufacturers upped their PWM frequency
to be between 16 K to 22 K to eliminate much of the noise.
Mikek

That would also make the LPF very much smaller.

Even going to 40 to 60 kHz makes the magnetics smaller. We still do not know
what is under the PCB for that unit.

tm

On Sun, 24 Mar 2013 02:28:00 -0400, "Michael A. Terrell"
wrote:


wrote:

On Sat, 23 Mar 2013 22:27:41 -0400, "Michael A. Terrell"
wrote:


wrote:

On Fri, 22 Mar 2013 04:31:00 +0000 (UTC), Bimmer Owner
wrote:

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

That's an interesting idea.
http://www3.picturepush.com/photo/a/...g/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult


Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.
Or just get the special tester that is made to plug into the
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.


Is that cheaper than roll your own?
Definitely not, if you already have a multimeter - but it is easier
for the guys who can't figure out how to do it without butchering the
wiring harness.

amdx wrote:

that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

I see many Motor Speed Control Manufacturers upped their PWM frequency
to be between 16 K to 22 K to eliminate much of the noise.
Mikek
Sure, if you don't mind heating the motor up...

Jamie

wrote:

On Sun, 24 Mar 2013 02:28:00 -0400, "Michael A. Terrell"
wrote:


wrote:

On Sat, 23 Mar 2013 22:27:41 -0400, "Michael A. Terrell"
wrote:


wrote:

On Fri, 22 Mar 2013 04:31:00 +0000 (UTC), Bimmer Owner
wrote:

On Thu, 21 Mar 2013 20:01:20 -0400, clare wrote:

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

That's an interesting idea.
http://www3.picturepush.com/photo/a/...g/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult


Take a blown fuse and use it for a test connector with a cheap
50-0-50A meter. Then you can just plug it in in place of the fuse to
make the test. You won't even have to worry about the polarity. You
can use a high current shunt, & a digital meter if you want more
accuracy.
Or just get the special tester that is made to plug into the
fuseblock. Autel makes the MX101 and 201 (10 amp and 20 amp) units for
the lighter duty stuff.


Is that cheaper than roll your own?
Definitely not, if you already have a multimeter - but it is easier
for the guys who can't figure out how to do it without butchering the
wiring harness.


That type shouldn't be allowed to own any tools. They generally do
more damage than good. If they do get something to work, it rarely lasts
because they have no clue what because the problem.

I've seen too many vehicles that some idiot cut and patched back
together. One stepvan I bought years ago had a damaged harness and I
talked them down almost $1000 on the price. It was coming off lease
from a fleet, and they wanted to fix it themselves. i pointed out that
if they could repair it properly, it wouldn't be in that condition.
--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

Scott Dorsey wrote:

Michael A. Terrell wrote:
tm wrote:


Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.

I've seen 20W power resistors in TO-220 packages.

It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).


All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.


But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.

Have you looked at the National Semiconductor (Now part of T.I)
'Simple Switcher' series of controllers? Generally only one inductor
and a couple small electrolytics. A lot simpler than older designs, and
little noise because of the small footprint.


PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.

If it's a RoHS soldering issue, though, I would not be surprised.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

In article , jim beam wrote:

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

Yes, this is why you put an integrator stage after the pwm stage, so that
the motor sees nice filtered DC with very little of the PWM leftover.

Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

It's a cheap, reliable way of doing the job, if it's done right. It's clear
that it wasn't done right, but I'm still waiting to hear what was done wrong.
Given all the RoHS-related failures and the report that touching up solder
joints on the transistors fixes the problem, I am suspicious that it's a
soldering issue made worse by the extreme temperature cycling.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 03/25/2013 06:59 AM, Scott Dorsey wrote:
In article , jim beam wrote:

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

Yes, this is why you put an integrator stage after the pwm stage, so that
the motor sees nice filtered DC with very little of the PWM leftover.

Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.

you don't want to integrate the output, merely rub the shoulders off the
square waves to get the harmonics down. the whole point and benefit of
pwm is that you have full voltage full power available in each pulse.
that's how you can start and control a motor with high torque at low
rpm. if you integrate or smooth out the motor's supply, you effectively
lose that and the motor won't start or torque the same way or even at all.



that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

It's a cheap, reliable way of doing the job, if it's done right.

in this day and age, that's no longer true. motor control is one of the
hot ticket items on the silicon fab agenda, and has been for some time.
there are some great pwm options out there, and for not a lot of money.


It's clear
that it wasn't done right, but I'm still waiting to hear what was done wrong.
Given all the RoHS-related failures and the report that touching up solder
joints on the transistors fixes the problem, I am suspicious that it's a
soldering issue made worse by the extreme temperature cycling.

you definitely have a point there, but given the size and shape of that
heat sink, i don't think there's any way that silicon is getting
sufficient cooling, and is clearly way up against its ceiling. whether
that's accident or design is another matter, but the bottom line is that
it's an issue that spans multiple different module manufacturers across
multiple continents with different internal designs - that reduces the
probability of it being rohs and slaps it firmly into the vehicle
manufacturer's lap.


--
fact check required

On 03/24/2013 08:52 AM, amdx wrote:
that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

I see many Motor Speed Control Manufacturers upped their PWM
frequency to be between 16 K to 22 K to eliminate much of the noise.
Mikek

interesting.


--
fact check required

On 03/24/2013 02:30 PM, Jamie wrote:
amdx wrote:

that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the
motor coils cause it to vibrate and make a humming noise at the pwm
control frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

I see many Motor Speed Control Manufacturers upped their PWM
frequency to be between 16 K to 22 K to eliminate much of the noise.
Mikek
Sure, if you don't mind heating the motor up...

Jamie


good point - how much? sure, big motor coils, big inductors -so how to
balance against pulse frequency for a bigger motor like a blower fan?


--
fact check required

On 03/25/2013 06:42 AM, Michael A. Terrell wrote:

Scott Dorsey wrote:

Michael A. Terrell wrote:
tm wrote:


Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.

I've seen 20W power resistors in TO-220 packages.

It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).


All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.

if it's just a two-layer board, maybe. assuming you get the specs on
the chips of course. but you'll need more than two units and a whole
lot of patience trying to reverse the schematic if it's 4 or more
layers. and you still don't achieve anything more than having a broken
light bulb in your hand.

what you need to do is get the operational capacities of the /working/
unit, and work with those. that the unit is a black box is completely
irrelevant.




But if it had been a PWM device, there would have been some filtering in
there, inductors and capacitors to keep the noise from getting into the
power lines. Designing clean and quiet PWM controllers is not quite as
trivial as some folks have made it out to be.

Have you looked at the National Semiconductor (Now part of T.I)
'Simple Switcher' series of controllers? Generally only one inductor
and a couple small electrolytics. A lot simpler than older designs, and
little noise because of the small footprint.

/and/ a smaller footprint. the "because" is entirely due to the soft
switching they've achieved. soft switching is still "big science" -
there are still phd's being written on how to implement and design, both
with the types of semiconductor, and the circuits in which they're used.




PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

This is possible, if it is the transistors that are failing. I don't see
any big protection diodes in there either.

If it's a RoHS soldering issue, though, I would not be surprised.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."




--
fact check required

In article , jim beam wrote:
On 03/25/2013 06:59 AM, Scott Dorsey wrote:
In article , jim beam wrote:

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

Yes, this is why you put an integrator stage after the pwm stage, so that
the motor sees nice filtered DC with very little of the PWM leftover.

Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.

you don't want to integrate the output, merely rub the shoulders off the
square waves to get the harmonics down. the whole point and benefit of
pwm is that you have full voltage full power available in each pulse.
that's how you can start and control a motor with high torque at low
rpm. if you integrate or smooth out the motor's supply, you effectively
lose that and the motor won't start or torque the same way or even at all.

The more you rub off, the quieter the motor is! You start throwing stuff
in the KHz range into the motor, and it whines from magnetostriction.
The more of that you remove, the quieter it goes. Of course, if you make
it too quiet, people complain....
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 03/25/2013 08:10 AM, Scott Dorsey wrote:
In article , jim beam wrote:
On 03/25/2013 06:59 AM, Scott Dorsey wrote:
In article , jim beam wrote:

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the motor
coils cause it to vibrate and make a humming noise at the pwm control
frequency.

Yes, this is why you put an integrator stage after the pwm stage, so that
the motor sees nice filtered DC with very little of the PWM leftover.

Problem is that the integrator stage costs money and big electrolytics
tend to have limited life, so auto folks don't like doing that.

you don't want to integrate the output, merely rub the shoulders off the
square waves to get the harmonics down. the whole point and benefit of
pwm is that you have full voltage full power available in each pulse.
that's how you can start and control a motor with high torque at low
rpm. if you integrate or smooth out the motor's supply, you effectively
lose that and the motor won't start or torque the same way or even at all.

The more you rub off, the quieter the motor is!

true, but you don't want to "integrate" the full power individual pulses
down to a lower average otherwise it won't run or torque.


You start throwing stuff
in the KHz range into the motor, and it whines from magnetostriction.

they whine pretty effectively at centihertz too.


The more of that you remove, the quieter it goes. Of course, if you make
it too quiet, people complain....

they will surely complain if it doesn't run.


--
fact check required

On Fri, 22 Mar 2013 15:04:39 -0400, clare wrote:

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult

The 40 amp fuse is barely accessible (as can be seen from the photos).
It's not even easy to pull the fuse & even harder to replace it.
So, all I was saying was that it's actually rather difficult to insert
test leads into the empty fuse #F76 fuse holder.

I'd wager it 'can' be done - it's just going to take an hour or so
to get the leads in place.

On Sat, 23 Mar 2013 22:27:41 -0400, Michael A. Terrell wrote:

Take a blown fuse and use it for a test connector

That's an idea.

On Sun, 24 Mar 2013 09:24:13 -0400, Scott Dorsey wrote:

It does indeed look like a TO-220 from the pin spacing (since there are no
actual transistors in the photos, just spots from which they were removed).

I doubt anything was removed since all the authors of those pictures
are expressly NOT trying to remove anything.

Those round metal "dots" in the pictures are the five pin connectors
of the harness connector.

"Bimmer Owner" wrote in message
...
On Fri, 22 Mar 2013 15:04:39 -0400, clare wrote:

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult

The 40 amp fuse is barely accessible (as can be seen from the photos).
It's not even easy to pull the fuse & even harder to replace it.
So, all I was saying was that it's actually rather difficult to insert
test leads into the empty fuse #F76 fuse holder.

I'd wager it 'can' be done - it's just going to take an hour or so
to get the leads in place.


So go back to measuring at the battery terminals. Do you have or can you
borrow a clamp on DC ammeter? They are great for this sort of problem. You
don't even lose any skin that way.

"Bimmer Owner" wrote in message
...
On Sun, 24 Mar 2013 09:24:13 -0400, Scott Dorsey wrote:

It does indeed look like a TO-220 from the pin spacing (since there are
no
actual transistors in the photos, just spots from which they were
removed).

I doubt anything was removed since all the authors of those pictures
are expressly NOT trying to remove anything.

Those round metal "dots" in the pictures are the five pin connectors
of the harness connector.

Are there any other pictures of the module showing if or where the
transistors are attached to the heat sink?

Has anyone ever fully dissected the unit so you can see what is under the PC
board? Maybe an X-ray from several angles done at the dentist?

On Mon, 25 Mar 2013 15:51:34 +0000 (UTC), Bimmer Owner
wrote:

On Fri, 22 Mar 2013 15:04:39 -0400, clare wrote:

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/...g/12475043.jpg
Why would you have to cut the wires????
Simply remove the fuse and connect the ammeter. You guys make your
lives so difficult

The 40 amp fuse is barely accessible (as can be seen from the photos).
It's not even easy to pull the fuse & even harder to replace it.
So, all I was saying was that it's actually rather difficult to insert
test leads into the empty fuse #F76 fuse holder.

I'd wager it 'can' be done - it's just going to take an hour or so
to get the leads in place.
Bet I can do it in less than half an hour - without the MaxiTester
and in about 5 or 10 minutes with it.

On Mon, 25 Mar 2013 09:42:51 -0400, Michael A. Terrell wrote:

All those photos only show one side. I full reverse engineering
should be done to draw a full schematic but I've never had my hands on
that module. It would probably take a couple of them, because ot the
potting.

These photos show both sides.
http://www.bimmerfest.com/forums/sho...d.php?t=309399

Nothing was removed, so I can't figure out WHAT you guys are
saying is the transistor removed.

Can you circle one of these pictures to show WHERE you think
something was removed?

http://www.bimmerfest.com/forums/att...0&d=1363957253
http://www.bimmerfest.com/forums/att...d=1361831 815
http://www.bimmerfest.com/forums/att...d=1361837 887

On Fri, 22 Mar 2013 08:37:14 -0700, wrote:

If it's just a typical DC motor with two leads, apply 12V and
it should run full speed. You could [then] measure how many amps
it draws when running.

That makes a lot of sense!

Plus, it's easier to hook up leads to the harness connector than it
is to get a DMM lead on the impossibly hard-to-get-to 40Amp Fuse F76 for
the blower motor.

On Sat, 23 Mar 2013 07:20:44 -0700, jim beam wrote:

serious question - why did you buy it?

As for me, I fell sway to all the people saying how great the bimmer was.

It was only after I owned it, that I realized that BMW engineers knew
how to design a suspension and a drive train, but they had no idea
how to build a machine.

To their credit, some people say it's not the engineers fault as
they probably know by now that every single Bosch 5.7 ABS control
module fried in every one of the vehicles it was placed in, and that
the final stage unit cooked itself to death in every single BMW it
was ever placed in, and that the 2-bar plastic cooling system
sprang a leak on almost every single BMW ever built, etc.

In fact, there's absolutely NO WAY BMW can't know about these
egregious engineering flaws. So, the common conclusion is that
their customers don't care - so why should they.

To me, it smacks of 3rd-grade engineering from BMW, so, that's why
I, for one, am amazed (being an owner myself), how sophomoric BMW
engineering really is.

Disclaimer: Yet, the drive train is phenomenal!

On Mon, 25 Mar 2013 12:26:52 -0400, clare wrote:

I'd wager it 'can' be done - it's just going to take an hour or so
to get the leads in place.
Bet I can do it in less than half an hour - without the MaxiTester
and in about 5 or 10 minutes with it.

I'd be very happy to see pictures of the test leads in situ
because I personally tried (and succeeded) in getting the 40
amp blower motor fuse F76 out and back in, but I wouldn't
want to do it more than once in my life.

From memory, here's what I did:
.. I moved the passenger front seat as far back as I could
.. I lowered the passenger front seat back as far back as it goes
.. I removed the ignition key and disconnected the battery negative lead
.. I removed the panel from the bottom of the glovebox
.. I removed the Phillips screw and panel off to the passenger left kneecap
.. I lay upside down on the flattened passenger seat, head in the footwell
.. I located the general module III (GMIII)
.. With my arms bent wildly arms over my head, I disconnected harness connectors
.. The first enigmatic connector was the white connector X332
.. The next diabolical connector was the small black X253
.. And the last puzzling connector was the large black X254
.. By now, I could slightly see the yellow 40 & red 50 amp fuses F76 & F77
.. With a flathead 1/8" screwdriver, I lifted the yellow fuse F76 up & out
.. That took about an hour or three.
.. Putting the fuse back was even harder than removing it

On Mon, 25 Mar 2013 12:04:20 -0400, tm wrote:

Has anyone ever fully dissected the unit so you can see what is under the PC
board? Maybe an X-ray from several angles done at the dentist?

All I have are the following:
These photos show both sides.
http://www.bimmerfest.com/forums/sho...d.php?t=309399

Nothing was removed, so I can't figure out WHAT you guys are
saying is the transistor removed.

Can you circle one of these pictures to show WHERE you think
something was removed?

http://www.bimmerfest.com/forums/att...0&d=1363957253
http://www.bimmerfest.com/forums/att...d=1361831 815
http://www.bimmerfest.com/forums/att...d=1361837 887

On Mon, 25 Mar 2013 16:54:13 +0000 (UTC), Bimmer Owner
wrote:

On Sat, 23 Mar 2013 07:20:44 -0700, jim beam wrote:

serious question - why did you buy it?

As for me, I fell sway to all the people saying how great the bimmer was.

It was only after I owned it, that I realized that BMW engineers knew
how to design a suspension and a drive train, but they had no idea
how to build a machine.

To their credit, some people say it's not the engineers fault as
they probably know by now that every single Bosch 5.7 ABS control
module fried in every one of the vehicles it was placed in, and that
the final stage unit cooked itself to death in every single BMW it
was ever placed in, and that the 2-bar plastic cooling system
sprang a leak on almost every single BMW ever built, etc.

In fact, there's absolutely NO WAY BMW can't know about these
egregious engineering flaws. So, the common conclusion is that
their customers don't care - so why should they.

To me, it smacks of 3rd-grade engineering from BMW, so, that's why
I, for one, am amazed (being an owner myself), how sophomoric BMW
engineering really is.

Disclaimer: Yet, the drive train is phenomenal!
If the engine desnt burn to the ground due to oil leaks, or overheat
or run out of oil, because of all the problems with "ancilliary
systems"

On Mon, 25 Mar 2013 07:55:03 -0700, jim beam wrote:

that reduces the probability of it being rohs

What does ROHS mean?

Bimmer Owner wrote:

Can you circle one of these pictures to show WHERE you think
something was removed?

http://www.bimmerfest.com/forums/att...0&d=1363957253

Okay, notice on the lefthand photo, there are two sets of three solder joints
on the lefthand side of the board, which show signs of recent rework. There
are TO-220 transistors attached to them, which are behind the board and you
cannot see.

On the righthand photo the board is reversed... you can see two sets of three
holes on the righthand side of the board which is where those TO-220
transistors were attached. You can see that they overheated the board and
lifted pads in the process too.

But you cannot in either of these photos see the transistors or what the part
number on the face of them is. Knowing what kind of transistors are used
will go far toward explaining some possible failure modes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
Bimmer Owner wrote:

Can you circle one of these pictures to show WHERE you think
something was removed?

http://www.bimmerfest.com/forums/att...0&d=1363957253

Okay, notice on the lefthand photo, there are two sets of three solder
joints
on the lefthand side of the board, which show signs of recent rework.
There
are TO-220 transistors attached to them, which are behind the board and
you
cannot see.

On the righthand photo the board is reversed... you can see two sets of
three
holes on the righthand side of the board which is where those TO-220
transistors were attached. You can see that they overheated the board and
lifted pads in the process too.

But you cannot in either of these photos see the transistors or what the
part
number on the face of them is. Knowing what kind of transistors are used
will go far toward explaining some possible failure modes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Yes, what Scott said. Where are the two transistors that were soldered in
the pair of three holes on the right of the right photo.

jim beam wrote:

i wish something would stop you. like self-awareness.

Says the idiot who says it overheats "because it's linear", as if
proper design (adequate heat-sinking) can't prevent overheating in a
"linear" design. Sheesh.

On 03/25/2013 05:57 PM, Jamie wrote:
jim beam wrote:

On 03/24/2013 02:30 PM, Jamie wrote:

amdx wrote:

that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

well, you live and learn. apparently the reason they use a linear
controller is because it allows the fan to run near silently at low
speed. with pwm control the fluctuating magnetic fields in the
motor coils cause it to vibrate and make a humming noise at the pwm
control frequency.

that doesn't of course get around the fact that the unit in question
here is apparently badly under rated, but the above does at least
explain why it's used.

I see many Motor Speed Control Manufacturers upped their PWM
frequency to be between 16 K to 22 K to eliminate much of the noise.
Mikek

Sure, if you don't mind heating the motor up...

Jamie


good point - how much? sure, big motor coils, big inductors -so how
to balance against pulse frequency for a bigger motor like a blower fan?

THe problem is eddy currents at high pulse rates. Between the wire
used and the core you can get heating in the motor..

Most inverters or pulsers for industrial drives tend to operate in the
8kHz range, that seems to be a good compromise.

Another way to do this, is to have an inductor on board with the
speed control circuit. You would PWM that inductor in series to a filter
cap
on the output which will then give you a clean variable DC. THe inductor
will be doing all variable voltages.

ok, as i understand it, and as i said to scott earlier, this is a
problem because it mungs low speed motor start and low speed torque.


This is a form of a PFC type of
supply and the only heat you get is from the DC coil R in the inductor
and the heat from the switching MOSFET, which should both be rather
low. BY doing it this way, you could operate a switcher at lets say up
in the 100kHz or more range and this would keep the size of the caps and
inductor small.

It is cheaper to use the motor as the inductor for PWM control but,
it also can radiate noise on the lead wires. I guess one could actually
mount the speed control directly on the motor using PWM and the noise
problem should be minimum.

this seems to be the problem. you can get good efficient control at a
few hundred hz, but it's super noisy. if you take the frequency up
above audio, bigger motors seem to be more of an issue.



Calculating the cost between the two, BMW most likely decided to go
with the basic linear type, Because why should they care? It'll most
likely make it past it's warranty!

you got that right - and it would go a lot further past its warranty if
it was better rated.


--
fact check required