Root cause insight into the common BMW blower motor resistor

[tm]

"Bimmer Owner" <dontaskfor@mymail.com> wrote in message
news:kist1k$jpd$8@news.albasani.net...

On Tue, 26 Mar 2013 14:56:21 -0400, tm wrote:

Any evidence it was checked with a scope?

Yes.

This quote below is verbatim from this location:
http://www.bimmerfest.com/forums/showpost.php?p=6536514&postcount=131

Hi, After soldering the lost/refound component,
remaking the joints of the 2 mosfet and testing the FSU alone with an
oscilloscope, here are my observations:

- the FSU works again

- there is no PWM , the gates signals are continuous voltage only , this
is the reason why it heat so much its aluminium box... In fact there is no
point on the board where square signals are present. Can somebody check
its own FSU if it's the same ?

- the 2 bridges are in fact 2 resistors 10 milliohm used to balance the
currents between the 2 MOSFET and balance the power also. The mesure of
the DC voltage on those resistors can be used to evaluate the current of
the blower and its worn state.

- I guess the principal duty of the computer on the other side is
switching off the power transistors if the control voltage goes under 1V.

I put the FSU back in the car and it still work, I don't know if it will
last long. because of the heat...

Olivier

http://www.bimmerfest.com/forums/attachment.php?attachmentid=306784&d=1325522788

Ok, they are most likely transistors and the two straps are combining the
emitters. Is the center junction of the two straps connected to the motor?

Does the red jumper connect to the 40 amp fuse? If both of those are a yes,
then they are most likely NPN power transistors and the jumper ties the
collectors together. Or power darlingtons. And it is just a linear supply.

In your other pictures, the spring clips just hold the transistors against
the heat sink.

 

[tm]

"Bimmer Owner" <dontaskfor@mymail.com> wrote in message
news:kistlq$jpd$9@news.albasani.net...

On Tue, 26 Mar 2013 19:24:08 +0000, Bimmer Owner wrote:

there will be no way to read the numbers on the two transistors.

I only found 1 transistor.
http://www1.picturepush.com/photo/a/12516119/img/12516119.jpg

This is what is suggested in this quote below:

There is only ONE mosfet in the FSU and I would forget
about trying to replace it even if you had one. Also, we have no reason
to believe the mosfet has caused any FSUs to fail. I have yet to see the
resistors in any of the picture shown anywhere in this thread.
Can someone circle the resistors for me? I would think they would be
fairly
decent wattage so they would be very easy to see, but I don't see any
resistors.

I think he is incorrectly calling the SMT IC a mosfet.

What went in the other three holes on the PC board?
What was under the two spring clips on the heat sink?

 

[Bimmer Owner]

On Tue, 26 Mar 2013 14:09:11 -0400, Michael A. Terrell wrote:

I think the IC is a dual, high side motor driver IC

It might be, but this Russian site intimates it's a temperature
compensated voltage controller.
http://tinyurl.com/crg2sms
http://kazus.ru/schematics/electrical-engineering/search/go/?text=%D0%C5%C3%D3%CB%DF%D2%CE%D0%20ELMOS%2010901D&nohistory=1&h=1
http://monitor.espec.ws/section27/topic189041.html
http://item.taobao.com/item.htm?id=13918440884

Translation below:
REGULATOR ELMOS 10901D
Found: 100 Showing: 1 - 10
Car Voltage Regulator
Category: Car
Source: Radioland country Electronics
Temperature controller cabin air KAMAZ
Category: Car
Source: Plans radiokonstruktsy
Simple Temperature compensated voltage regulator. Controller together with thyristor-transistor electronic ignition unit with a long spark, ensuring the rapid start-ups at various operating conditions, allowed to increase battery life of up to nine years.
Category: Car
Source: For the life of a soldering iron ...
Regulator for automotive windshield
Category: Car
Source: MASTER KIT
The controller measures the wiper-this control is designed to use regular mode switch blades and is contactless.
Category: Car
Source: For the life of a soldering iron ...
Temperature compensated voltage regulator device in some ways superior designs. The controller can be used as a universal device is suitable not only for mounting on any car, but everywhere, where the generator rotor speed is variable (eg, wind power). Choose the appropriate control elements, it can be easily adapted to work with any voltage (up to 400V) and excitation current (tens of amperes).
Category: Car
Source: For the life of a soldering iron ...
Voltage regulator 2012.3702, 22.3702, 221.3702
Category: Car
Source: For the life of a soldering iron ...
Voltage regulator 201.3702
Category: Car
Source: For the life of a soldering iron ...
Voltage Regulator 13.3702
Category: Car
Source: For the life of a soldering iron ...
Voltage regulator RR132A, 1112.3702
Category: Car
Source: For the life of a soldering iron ...

 

[Nate Nagel]

On 03/26/2013 03:00 PM, tm wrote:

"Nate Nagel" <njnagel@roosters.net> wrote in message
news:kisqep418lt@news4.newsguy.com...
On 03/26/2013 12:35 PM, tm wrote:

"Bimmer Owner" <dontaskfor@mymail.com> wrote in message
news:kisfan$ott$4@news.albasani.net...
On Tue, 26 Mar 2013 08:56:22 -0400, Scott Dorsey wrote:

one person figuring the failure mode out might save a
lot of people that grief.

But mostly it's just intellectual curiosity.

Exactly!


I don't even own a BMW. After this thread, I don't think I ever will.

Like I said before, don't drive one then. It's kind of like going on
a date with that unbelievably attractive female type who is also
smart, witty, fun to be around, actually seems to like you, and oh by
the way is completely mentally unhinged.

Suddenly you find yourself putting up with all sorts of stuff that you
wouldn't, otherwise... (now that said, touch wood, current ride has
exhibited none of the known issues... which reminds me, I need to
call and schedule the battery cable recall @ the stealership)

nate

--


LOL. There's more truth to that then you may think.

Sadly, I speak from experience, in both respects.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

 

[trader4@optonline.net]

On Mar 26, 12:22 pm, "Francis C." <f...@fc.com> wrote:

Scott Dorsey wrote:
trad...@optonline.net <trad...@optonline.net> wrote:
It's not like they are a $500 or $1000 puter.  Don't they cost like $50?
I mean how much is time worth trying to reverse engineer it.....

Bear in mind that the $75 Sitronic Ebay FSU is known to be even
more faulty than the $175 Valeo FSU from the stealer.

I can think of nice test equipment to buy instead of a $175 FSU every
few years!

I feel your pain. I have a 1980 MB 300SD. For the AC,
MB used a part from Chrysler that they used on the Imperial.
It's the size of a grapefruit and it controls the entier HVAC
system. In that one widget you have a valve that's in the
path of the engine coolant system that goes to the heater,
about a dozen vacuum hoses that control the various
flaps. You also have the electical outputs for the blower,
AC clutch, etc. And all that is driven by a small electric motor
that is inside the thing. The motor is part of a feedback
servo system that moves in relation to the desired temp
setting vs the actual. It goes from max cooling, to max
heating. Oh, and a critical part of that sytem is the
potentiometer inside that widget, the resistance value
of which changes based on the current position of the
motor that works the whole thing, moving it from max
cooling to max heat.

So, you have hot engine coolant, vacuum, electrical,
a potentiometer, all inside one widget. How smart is
that? The typical failure mechanism is that the plastic
housing cracks and it leaks coolant. They were up to
$600 in the 90s for a new one. Some guy down in
TN started a business rebuilding them. His uses an
aluminum housing for the part where the valve and
hot coolant are. I bought one 10 years ago for $500.
It's been fine until recently. Now it's starting to have
problems. Haven't had a chance to find out what's wrong.

 

[Bimmer Owner]

On Tue, 26 Mar 2013 14:46:25 -0400, tm wrote:

Here's what the heatsink looks like when I cut into it today:
http://www4.picturepush.com/photo/a/12515572/img/12515572.jpg


Ha, keep going!

Well, I only had lunchtime, and it got uglier & uglier as I went!
http://www5.picturepush.com/photo/a/12515993/img/12515993.jpg
http://www4.picturepush.com/photo/a/12515997/img/12515997.jpg
http://www2.picturepush.com/photo/a/12516000/img/12516000.jpg
http://www3.picturepush.com/photo/a/12516001/img/12516001.jpg
http://www2.picturepush.com/photo/a/12516005/img/12516005.jpg
http://www1.picturepush.com/photo/a/12516009/img/12516009.jpg

Unless there is some chemical way to remove that black/gray
rubbery (like a tough pencil eraser) gunk, there will be no
way to read the numbers on the two transistors.

 

[Bimmer Owner]

On Tue, 26 Mar 2013 15:04:51 -0400, tm wrote:

Here is the Elmos 10901D chip of my FSU as I cut it open today.
http://www4.picturepush.com/photo/a/12515632/img/12515632.jpg

Are those the two transistors sitting on top?

Actually, it's the same transistor, which broke in half while
I was attempting to get the black rubber eraser stuff off of it
to read the numbers.

It's really going to be HARD to read those numbers now...
http://www4.picturepush.com/photo/a/12516062/img/12516062.jpg

 

[Bimmer Owner]

On Tue, 26 Mar 2013 14:56:21 -0400, tm wrote:

Any evidence it was checked with a scope?

Yes.

This quote below is verbatim from this location:
http://www.bimmerfest.com/forums/showpost.php?p=6536514&postcount=131

Hi, After soldering the lost/refound component,
remaking the joints of the 2 mosfet and testing the FSU alone with an
oscilloscope, here are my observations:

- the FSU works again

- there is no PWM , the gates signals are continuous voltage only , this is the reason why it heat so much its aluminium box... In fact there is no point on the board where square signals are present. Can somebody check its own FSU if it's the same ?

- the 2 bridges are in fact 2 resistors 10 milliohm used to balance the currents between the 2 MOSFET and balance the power also. The mesure of the DC voltage on those resistors can be used to evaluate the current of the blower and its worn state.

- I guess the principal duty of the computer on the other side is switching off the power transistors if the control voltage goes under 1V.

I put the FSU back in the car and it still work, I don't know if it will last long. because of the heat...

Olivier

http://www.bimmerfest.com/forums/attachment.php?attachmentid=306784&d=1325522788

 

[Bimmer Owner]

On Tue, 26 Mar 2013 19:24:08 +0000, Bimmer Owner wrote:

there will be no way to read the numbers on the two transistors.

I only found 1 transistor.
http://www1.picturepush.com/photo/a/12516119/img/12516119.jpg

This is what is suggested in this quote below:

There is only ONE mosfet in the FSU and I would forget
about trying to replace it even if you had one. Also, we have no reason
to believe the mosfet has caused any FSUs to fail. I have yet to see the
resistors in any of the picture shown anywhere in this thread.
Can someone circle the resistors for me? I would think they would be fairly
decent wattage so they would be very easy to see, but I don't see any
resistors.

 

[trader4@optonline.net]

On Mar 26, 3:31 pm, Bimmer Owner <dontask...@mymail.com> wrote:

On Tue, 26 Mar 2013 14:56:21 -0400, tm wrote:
Any evidence it was checked with a scope?

Yes.

This quote below is verbatim from this location:
 http://www.bimmerfest.com/forums/showpost.php?p=6536514&postcount=131

Hi, After soldering the lost/refound component,
remaking the joints of the 2 mosfet and testing the FSU alone with an
oscilloscope, here are my observations:

- the FSU works again

- there is no PWM ,

You said you tested the FSU alone. If so, how can you
say there is no PWM signal between the car and FSU?


the gates signals are continuous voltage only , this is the reason
why it heat so much its aluminium box... In fact there is no point on
the board where square signals are present. Can somebody check its own
FSU if it's the same ?

- the 2 bridges are in fact 2 resistors 10 milliohm used to balance the currents between the 2 MOSFET and balance the power also. The mesure of the DC voltage on those resistors can be used to evaluate the current of the blower and its worn state.

Say what? 10 milliohms is .01 ohms. How could that
possibly balance the power to a motor in a 40 amp circuit?

- I guess the principal duty of the computer on the other side is switching off the power transistors if the control voltage goes under 1V.

Which makes no sense at all.

I put the FSU back in the car and it still work, I don't know if it will last long. because of the heat...

Olivier

http://www.bimmerfest.com/forums/attachment.php?attachmentid=306784&d....

It seems they last at least a few years. Maybe it's like
gas. You buy it and you go so far. I think you're in way
over your head here;

 

[trader4@optonline.net]

On Mar 26, 3:51 pm, "tm" <No_one_h...@white-house.gov> wrote:

"Bimmer Owner" <dontask...@mymail.com> wrote in message

news:kist1k$jpd$8@news.albasani.net...





On Tue, 26 Mar 2013 14:56:21 -0400, tm wrote:

Any evidence it was checked with a scope?

Yes.

This quote below is verbatim from this location:
http://www.bimmerfest.com/forums/showpost.php?p=6536514&postcount=131

Hi, After soldering the lost/refound component,
remaking the joints of the 2 mosfet and testing the FSU alone with an
oscilloscope, here are my observations:

- the FSU works again

- there is no PWM , the gates signals are continuous voltage only , this
is the reason why it heat so much its aluminium box... In fact there is no
point on the board where square signals are present. Can somebody check
its own FSU if it's the same ?

- the 2 bridges are in fact 2 resistors 10 milliohm used to balance the
currents between the 2 MOSFET and balance the power also. The mesure of
the DC voltage on those resistors can be used to evaluate the current of
the blower and its worn state.

- I guess the principal duty of the computer on the other side is
switching off the power transistors if the control voltage goes under 1V.

I put the FSU back in the car and it still work, I don't know if it will
last long. because of the heat...

Olivier

http://www.bimmerfest.com/forums/attachment.php?attachmentid=306784&d....

Ok, they are most likely transistors and the two straps are combining the
emitters. Is the center junction of the two straps connected to the motor?

Does the red jumper connect to the 40 amp fuse? If both of those are a yes,
then they are most likely NPN power transistors and the jumper ties the
collectors together. Or power darlingtons. And it is just a linear supply..

In your other pictures, the spring clips just hold the transistors against
the heat sink.- Hide quoted text -

- Show quoted text -

The main points of his post, like the "two bridges that are .01 ohm
resistors, that "balance" the motor don't
concern you in the least?

Blind leading the blind

 

[Bimmer Owner]

On Tue, 26 Mar 2013 19:41:47 +0000, Bimmer Owner wrote:

Can someone circle the resistors for me? I would think they would be fairly
decent wattage so they would be very easy to see, but I don't see any
resistors.

I 'think' (but I'm not sure) that these are the resistors in series:
http://www5.picturepush.com/photo/a/12516343/img/12516343.jpg

 

[Bimmer Owner]

There is only ONE mosfet in the FSU

I'm still trying to figure out if there was only one or two:
http://www2.picturepush.com/photo/a/12516370/img/12516370.jpg

 

[trader4@optonline.net]

On Mar 26, 4:09 pm, Bimmer Owner <dontask...@mymail.com> wrote:

On Tue, 26 Mar 2013 19:41:47 +0000, Bimmer Owner wrote:
Can someone circle the resistors for me? I would think they would be fairly
decent wattage so they would be very easy to see, but I don't see any
resistors.

I 'think' (but I'm not sure) that these are the resistors in series:
 http://www5.picturepush.com/photo/a/12516343/img/12516343.jpg

If they are resistors, I've never seen any that look like that.
Also, given that you want to thermally bond any components
that generate major heat, why are they not heat sinked?
With any power design I've seen, the key components, eg
the transistors are directly bonded to the heat sink.

 

[tm]

<trader4@optonline.net> wrote in message
news:cbc31f8a-3463-4a02-a9be-06a9a13bcd0e@y4g2000yqa.googlegroups.com...
On Mar 26, 3:51 pm, "tm" <No_one_h...@white-house.gov> wrote:

"Bimmer Owner" <dontask...@mymail.com> wrote in message

news:kist1k$jpd$8@news.albasani.net...





On Tue, 26 Mar 2013 14:56:21 -0400, tm wrote:

Any evidence it was checked with a scope?

Yes.

This quote below is verbatim from this location:
http://www.bimmerfest.com/forums/showpost.php?p=6536514&postcount=131

Hi, After soldering the lost/refound
component,
remaking the joints of the 2 mosfet and testing the FSU alone with an
oscilloscope, here are my observations:

- the FSU works again

- there is no PWM , the gates signals are continuous voltage only , this
is the reason why it heat so much its aluminium box... In fact there is
no
point on the board where square signals are present. Can somebody check
its own FSU if it's the same ?

- the 2 bridges are in fact 2 resistors 10 milliohm used to balance the
currents between the 2 MOSFET and balance the power also. The mesure of
the DC voltage on those resistors can be used to evaluate the current of
the blower and its worn state.

- I guess the principal duty of the computer on the other side is
switching off the power transistors if the control voltage goes under
1V.

I put the FSU back in the car and it still work, I don't know if it will
last long. because of the heat...

Olivier

http://www.bimmerfest.com/forums/attachment.php?attachmentid=306784&d...

Ok, they are most likely transistors and the two straps are combining the
emitters. Is the center junction of the two straps connected to the motor?

Does the red jumper connect to the 40 amp fuse? If both of those are a
yes,
then they are most likely NPN power transistors and the jumper ties the
collectors together. Or power darlingtons. And it is just a linear supply.

In your other pictures, the spring clips just hold the transistors against
the heat sink.- Hide quoted text -

- Show quoted text -

The main points of his post, like the "two bridges that are .01 ohm
resistors, that "balance" the motor don't
concern you in the least?

Blind leading the blind
=============================================

It is common to place low value resistors in the emitters to balance the
current in two paralleled devices.
0.01 ohms would be very realistic in a 40 amp system.

As to blind, you exhibit that trait much better than anyone else involved
with this thread.
Asshole.

 

[tm]

<trader4@optonline.net> wrote in message
news:3d3144f3-a011-49e6-a07c-e6e576e0185a@5g2000yqz.googlegroups.com...
On Mar 26, 3:31 pm, Bimmer Owner <dontask...@mymail.com> wrote:

On Tue, 26 Mar 2013 14:56:21 -0400, tm wrote:
Any evidence it was checked with a scope?

Yes.

This quote below is verbatim from this location:
http://www.bimmerfest.com/forums/showpost.php?p=6536514&postcount=131

Hi, After soldering the lost/refound component,
remaking the joints of the 2 mosfet and testing the FSU alone with an
oscilloscope, here are my observations:

- the FSU works again

- there is no PWM ,

/You said you tested the FSU alone. If so, how can you
/say there is no PWM signal between the car and FSU?


/ the gates signals are continuous voltage only , this is the reason
/why it heat so much its aluminium box... In fact there is no point on
/the board where square signals are present. Can somebody check its own
/FSU if it's the same ?

- the 2 bridges are in fact 2 resistors 10 milliohm used to balance the
currents between the 2 MOSFET and balance the power also. The mesure of
the DC voltage on those resistors can be used to evaluate the current of
the blower and its worn state.

/Say what? 10 milliohms is .01 ohms. How could that
/possibly balance the power to a motor in a 40 amp circuit?

Not to the motor idiot. To the transistors.

- I guess the principal duty of the computer on the other side is
switching off the power transistors if the control voltage goes under 1V.

/Which makes no sense at all.


Certainly not to you.

I put the FSU back in the car and it still work, I don't know if it will
last long. because of the heat...

Olivier

http://www.bimmerfest.com/forums/attachment.php?attachmentid=306784&d...

/It seems they last at least a few years. Maybe it's like
/gas. You buy it and you go so far. I think you're in way
/over your head here;

But not yours?

 

[tm]

"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:lpp4t.25117$Z16.7270@newsfe04.iad...

Bimmer Owner wrote:

On Mon, 25 Mar 2013 21:42:16 -0700, jim beam wrote:


or google for this guy:
"ESI 695 80 Amps DC/AC Low Current Probe"


This seems to only be $107 but it doesn't say whether it works
with the Fluke 75 or not.
http://www.amazon.com/ESI-695-Amps-Current-Probe/dp/B000FN4IUK



Actually that looks good and should work just fine.

That type of probe is self contained, meaning it does
not depend on the DMM input impedance for proper match.

BUt 80 Amps is kind of small I think, I have a AC/DC clamp
that does 800 amps, but to do low current readings of less than 1
amp becomes a problem with AC. DC I can zero it.

Jamie

You can increase the sensitivity by winding multiple turns around the clamp

on core.

Two turns makes it a 400 amp meter and so on.

 

[Michael A. Terrell]

Bimmer Owner wrote:

On Tue, 26 Mar 2013 14:23:08 -0400, Michael A. Terrell wrote:

That heatsink is small.

Here's what the heatsink looks like when I cut into it today:
http://www4.picturepush.com/photo/a/12515572/img/12515572.jpg

I was never crazy about that style of heatsink.


--

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]

"trader4@optonline.net" wrote:

On Mar 26, 4:09 pm, Bimmer Owner <dontask...@mymail.com> wrote:
On Tue, 26 Mar 2013 19:41:47 +0000, Bimmer Owner wrote:
Can someone circle the resistors for me? I would think they would be fairly
decent wattage so they would be very easy to see, but I don't see any
resistors.

I 'think' (but I'm not sure) that these are the resistors in series:
http://www5.picturepush.com/photo/a/12516343/img/12516343.jpg

If they are resistors, I've never seen any that look like that.

You've never seen strips of nichrome in a space heater?


--

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]

Bimmer Owner wrote:

There is only ONE mosfet in the FSU

I'm still trying to figure out if there was only one or two:
http://www2.picturepush.com/photo/a/12516370/img/12516370.jpg

Two.

--

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.