I have tried to repair the FSU for BMW e46 by replacing the two MOSFET transistors with equivalent: IRF3205 (and even two more powerful) but it seems they cannot do the job due to other electronic component which i cannot figure out. Even though there is a change on G -gate the transistor won't change the flow ..there must be something on the Base or Collector ... I'm stunned cause i tried repairing two of them

On Thursday, November 14, 2013 7:37:33 AM UTC-5, wrote:
I have tried to repair the FSU for BMW e46 by replacing the two MOSFET transistors with equivalent: IRF3205 (and even two more powerful) but it seems they cannot do the job due to other electronic component which i cannot figure out. Even though there is a change on G -gate the transistor won't change the flow ..there must be something on the Base or Collector ... I'm stunned cause i tried repairing two of them

Root cause is BMW designed/specd a piece of crap and
doesn't give a damn about resolving it, even thouh it's
been an obvious problem for a decade, guys like you
have bitched about it and their service people obviously
know about it.

They've achieved some other marvels of engineering, like
putting electronics inside the aux fan that sits in front
of the hot radiator, to vary the fan speed. Simple on/off
fan wasn't good enough. So, they put electronics in an
environment where it gets 130F, salt, water, God knows what.
Of course they fail. And you can't even diagnose it because
no one knows what kind of signal they send it to turn it on,
off, fast, slow, etc. BMW can, with their magic computer that
they can hook up to turn it on and off. So, every 2 years
you buy a new one for $275 aftermarket price, plus labor.
Go to BMW and get the OEM part, it's $750 by the time you're
done and they still fail.

Another favorite is how they manage to use a vast assortment
of cable connectors that even upon careful examination, you
can't figure out how they come apart. And that's assuming you
can see it well, right in front of you.

I've had basic American cars that went 100K+ miles with
no CV boot joint failures. A friend just got rid of a
Honda CRV with 200K+ miles and no CV boot failures.
Friend has an X5 and it went through 2 of them in less than 75K
miles. At 140K, they're shot again. The rubber boot on
the intake manifold also failed at 75K. Obviously their rubber
boot products are crap, but they don't care.

Or how about their window system in the X5, where they use
crappy cables to hold the windows up? I've seen those fail
with the car sitting in the driveway. Cable snaps, window
falls down and smashes to bits. Not on just one window, I
saw it happen on two different ones in a friends car.

But, you're already planning on buying your next $75K BMW wonder
car, right?

On 11/14/2013 11:48 AM, wrote:
On Thursday, November 14, 2013 7:37:33

AM UTC-5, wrote:
I have tried to repair the FSU for BMW e46
by replacing the two MOSFET transistors with
equivalent: IRF3205 (and even two more powerful)
but it seems they cannot do the job due to other
electronic component which i cannot figure out.
Even though there is a change on G -gate the
transistor won't change the flow ..there must
be something on the Base or Collector ... I'm
stunned cause i tried repairing two of them


But, you're already planning on buying your next $75K BMW wonder
car, right?


Do you get many on topic comments on a home
repair list?

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

wrote:
On Thursday, November 14, 2013 7:37:33 AM UTC-5, wrote:
I have tried to repair the FSU for BMW e46 by replacing the two MOSFET transistors with equivalent: IRF3205 (and even two more powerful) but it seems they cannot do the job due to other electronic component which i cannot figure out. Even though there is a change on G -gate the transistor won't change the flow ..there must be something on the Base or Collector ... I'm stunned cause i tried repairing two of them



Hi,
Checked/set proper bias voltage for the replacement MOSFET?
If you don't know how or can't do it they won't work properly for sure.


Root cause is BMW designed/specd a piece of crap and
doesn't give a damn about resolving it, even thouh it's
been an obvious problem for a decade, guys like you
have bitched about it and their service people obviously
know about it.

They've achieved some other marvels of engineering, like
putting electronics inside the aux fan that sits in front
of the hot radiator, to vary the fan speed. Simple on/off
fan wasn't good enough. So, they put electronics in an
environment where it gets 130F, salt, water, God knows what.
Of course they fail. And you can't even diagnose it because
no one knows what kind of signal they send it to turn it on,
off, fast, slow, etc. BMW can, with their magic computer that
they can hook up to turn it on and off. So, every 2 years
you buy a new one for $275 aftermarket price, plus labor.
Go to BMW and get the OEM part, it's $750 by the time you're
done and they still fail.

Another favorite is how they manage to use a vast assortment
of cable connectors that even upon careful examination, you
can't figure out how they come apart. And that's assuming you
can see it well, right in front of you.

I've had basic American cars that went 100K+ miles with
no CV boot joint failures. A friend just got rid of a
Honda CRV with 200K+ miles and no CV boot failures.
Friend has an X5 and it went through 2 of them in less than 75K
miles. At 140K, they're shot again. The rubber boot on
the intake manifold also failed at 75K. Obviously their rubber
boot products are crap, but they don't care.

Or how about their window system in the X5, where they use
crappy cables to hold the windows up? I've seen those fail
with the car sitting in the driveway. Cable snaps, window
falls down and smashes to bits. Not on just one window, I
saw it happen on two different ones in a friends car.

But, you're already planning on buying your next $75K BMW wonder
car, right?

Hi i just bought an fsu from behr for my 2002 e46 and i opened it . Inside was only one transistor 2n0605 from infineon and an elmos 10901d.The 2n0605 is 80 amps 55v mos.I am now working to figure out the exact schematics

In the past i replaced the transistor with some irf mosfet .they were powerfull but didnt work properly .now i know you have to put low voltage and hi amps mos.

wrote:
In the past i replaced the transistor with some irf mosfet .they were powerfull but didnt work properly .now i know you have to put low voltage and hi amps mos.

Hi,
If bias voltage does not match close enough heavier one won't function
properly. Is there a way to improve cooling by heat sinking or applying
proper thermal paste?

On Tuesday, February 4, 2014 11:11:36 AM UTC-5, wrote:
Hi i just bought an fsu from behr for my 2002 e46 and i opened it . Inside was only one transistor 2n0605 from infineon and an elmos 10901d.The 2n0605 is 80 amps 55v mos.I am now working to figure out the exact schematics

Out of curiousity, how did you open it up? The ones I've seen
are potted in 1/2" deep epoxy, with no obvious way to get that out
without destroying what's inside....

Also, Ive been helping a friend with the FSU problem. His blower
went from working fine to not working at all. Being concerned about
all the apparently crap ones out there, bought one from a BMW dealer
that is marked Sitronic. It appeared to work, but..... With the
blower on high it will run all day, no problem. You can back the blower
off to about 80% and as you do so, the heat sink starts to get very
hot, but the blower still runs at 80%. If you back the speed down
anymore, it gets even hotter and then starts pulsating the blower,
finally stops all together. I tried dipping the end of the heatsink
rods into a container of water when it does that and within a couple
seconds the blower starts working again fine. So, it's definitely
heat related.

Any ideas on what's wrong? First impression would be that it's the new
FSU because the blower works on full or near full speed. But I guess
the other possibility is that the motor has a problem? Seems odd
though that a single winding type DC motor could run fine at full
speed, but then cause the FSU to overheat at lower speeds.

wrote in message
...

Also, Ive been helping a friend with the FSU problem. His blower
went from working fine to not working at all. Being concerned about
all the apparently crap ones out there, bought one from a BMW dealer
that is marked Sitronic. It appeared to work, but..... With the
blower on high it will run all day, no problem. You can back the blower
off to about 80% and as you do so, the heat sink starts to get very
hot, but the blower still runs at 80%. If you back the speed down
anymore, it gets even hotter and then starts pulsating the blower,
finally stops all together. I tried dipping the end of the heatsink
rods into a container of water when it does that and within a couple
seconds the blower starts working again fine. So, it's definitely
heat related.

Any ideas on what's wrong? First impression would be that it's the new
FSU because the blower works on full or near full speed. But I guess
the other possibility is that the motor has a problem? Seems odd
though that a single winding type DC motor could run fine at full
speed, but then cause the FSU to overheat at lower speeds.

Could be the motor. While not exectally correct, the motor requires a
cretain ammount of power. When running at full speed the transistor is
acting more like a swithc. At slower speeds it is acting more like a
resistor. Any power that is not used to get the motor to speed is converted
to heat in the FSU. The slower the motor is ran, the hotter the FSU will
get. If the bearings are going bad or there is some other reason the motor
is drawing more than the rated current the FSU will heat up more than
normal, especially at slower speeds.

Have you checked the current the motor is drawing and made sure it is
getting the voltage it is suspose to at full speed ?



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