failed blower resistor (final stage resistor) not really dead

Originally Posted by CompactWRC

It´s not possible because emisor pins and colector pins of the mosfets are connected among themselves.

MOSFETs (metal oxide semiconductor field effect transistors) don't have emitters or collectors.

They have a gate, drain, and a source.

Are you sure you're not talking about BJTs (bipolar junction transistors), which have a base, emitter, and a collector?

WRC you're right about the wiring, The 2 MOSFET drain and source are tied together but the gates are differents

On the picture , one of the component is gone with the rubber foam : its look like transistor : black with 3 pins ( it 's not bipolar transistors )
It happen to me also : the component gone so easily that I didn't realize it, maybe it is the issue for that FSU.
It is only while I compare to other pictures in the forum that there was a lack of component on my board.
fortunately I found it together with the rubber foam parts, so I will solder it back later

did you manage to extract completely the board from the box? I'm curious about the opposite side

Originally Posted by Trebbia

MOSFETs (metal oxide semiconductor field effect transistors) don't have emitters or collectors.

They have a gate, drain, and a source.

Are you sure you're not talking about BJTs (bipolar junction transistors), which have a base, emitter, and a collector?

You are right, what a mistake!

sorry electronics!

Originally Posted by olivier577

did you manage to extract completely the board from the box? I'm curious about the opposite side

In first post of page 4 you can see the two sides of the circuit.

I have come to the conclusion that the failure is in the transistor. In vacuum it can switch correctly to provide a 0-12 V exit but whit the motor fan connected (consuption of 6 A at full trottle) simply dont work.
Its a failure difficult to localize in a transistor and at first probably causes the overtemperature that broke solder pins (I resolder weeks ago and works), and in advanced transistor dies (actually).

I finally got a module in a scrapping because its very difficult to remove the gum to change transistor and a bad disipation of heat because a bad finish can cause a disaster.

Greetings

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

Originally Posted by olivier577

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

So the transistor works betweeen cut/saturation regions as a variable resistor?
but for this the potentiometer signal of the control panel could manage the gate directly and I found that both pins aren´t connected.

Maybe there is a PWM signal fron the microcontroller rectified and filtred as a DC signal.

I was looking for the datasheet of the microcontroler but dont exist whit this reference.

Yes the transitors works as variable resistors and a big waste of power goes into heat
but the advantage can be that there is no high current switching who could interfere with other electronic on the car (eg radio)

I didn't found any pwm signal on the 1st side of the board, but maybe on the chip side ??
or maybe my FSU has a little problem too, to check this I need another FSU to test...
If somebody needs to get rid of his failed FSU please email me...

about the chip, I bet the firm written on it ,ELMOS, is only the one who order the chip and designed the board, on their site they wrote that they program asic also. If I'm right nobody can find datasheet about that reference except ELMOS themselves.

Wow, didn't think it would work, but as soon as I removed the PU protective layer, I saw 6 pins with bad cracked soldering. Cleaned it a little with SS brush, cotton eartip with little S39 and resoldered. Removed the S39 with toothbrush and little water and tested it before filling the cavity with silicone.... Saved me some money. Thanks for this clear post.
gr Maurice

Originally Posted by kraft

This a well know trouble with the A/C computer talking to a deaf unit, the final stage resistor.
Today i found something that you may find interesting, at least for those who have this issue, fan not working anymore or working for a moment and then stop or with a fan that is not that efficient as it should be.
.....

Hi,

I've had the same battery drain issue on my 2003 E39 530i. The A/C module was at fault and the fan was always running which drained the battery overnight. The way I fixed this is by finding a fuse (located in the glove compartment) which cuts the power at the ignition, rewire and reposition the A/C module fuse. Now it works like a charm.

If you need more details please let me know and I'll post more technical instructions.

This is a clever fix but:
- You turn a unswitched circuit into a switched circuit, not a bad idea.
- As long as the car runs, the fan will always run.

Given this current diagnostic problem:
> E39 (1997 - 2003) > Detailed step by step diagnostic DIY ... dead battery ... parasitic current drain

And, using information from this thread (and others), I opened a NEW thread solely to ask:
> E39 (1997 - 2003) > Do we have a DIY for how to build a test jig testing FSU/FSR operation on the bench?

Here are some graphics I created for that thread, most of which came from this thread:
> E39 (1997 - 2003) > failed blower resistor (final stage resistor) not really dead

Notice the ELMOS 10901D integrated circuit (16 pin surface mount chip), reputedly a "temperature compensated voltage regulator".
http://monitor.espec.ws/section27/topic189041.html







See also:
- What is the canonical thread on the BMW E39 FSU/FSR/Blower Motor Resistor (1) and what is the right brand FSR to purchase (1) (2) when your interior heating & air conditioning HVAC/IHKA blower motor goes haywire (1) (2) (3) (4) (5) (6) (7) (8) & how to test the FSU (1) (2) (3) & how to repair your own final stage resistor including an autopsy & wiring diagram schematic (1) (2) and why a bad final stage unit will cause the battery to drain overnight (1) (2) (3) & how to isolate and replace the E39 blower motor (1) (2) (3) (4) (5) (6) & how not to replace the FSU (1)

Originally Posted by cn90

This is a clever fix but:
- You turn a unswitched circuit into a switched circuit, not a bad idea.
- As long as the car runs, the fan will always run.

Much easier to buy a new one. They are under $50

Seems like allot of work for a pretty cheap part even OEM BMW which you know will work.You have to figure your time is worth something I usually charge myself 1/2 my shop
rate then I can keep track of how much I'm putting into a project even if it's my own.

Originally Posted by ninetyseven

They are under $50

What irks me to no end is the fact we have to periodically buy a $50 part every few years just because BMW and their suppliers couldn't design a device to control a simple blower motor to save their lives.

The sad part (and the part that irks me most), is that they actually profit from their lousy design - in that millions of us are shelling out that $50 every few years. In effect, we're REWARDING them for their lousy design.

So, it behooves us to UNDERSTAND what is going wrong in these FSUs, rather than simply play dumb and fork over the money, time and time and time and time again.

Anyway, I tested the FSU harness connector voltage and resistance values with the key out of the ignition, and found the voltage to be over 12 volts and the resistance of the blower motor to be 0.5 ohms at the FSU harness connector.

once by dealer within warranty period with old style FSU, A few years later outside of warranty it failed. I replaced it with newer version, more fins, no issues since . my car a 2000 528 is 13 years old. I know I just jinksed my self,

The filler is a papery gray substance, black only on top. Do you think I can melt it out more gracefully than chiseling?
(I'm worried about damaging the components on the board, as some have done above.)

I wasn't sure whether to start a new short thread, or to post here, but, I've seen enough butchered keys and plastic flakes in ABS control module goop to ask before attempting to clean out my FSU.

There are plenty of pictures of cleaned out FSUs (showing the circuit board), and even some (see above) where they broke components off the circuit board, but no pictures (to my knowledge) of HOW they removed the black goop at the bottom of the FSU.

So, before I ruin mine, may I ask: How do you suggest we clean this stuff out without damaging the circuit board underneath. (I really wish I knew what I was doing.)

How deep is that circuit board anyway?
The fill looks VERY shallow in some of the pictures - but my chisel went in deeply as shown below.
FIRST PASS:


EDIT: What 'is' this gray papery stuff anyway? It seems to have filaments throughout it, like heavy cardboard or something?
SECOND PASS:


On this third pass, I hit some of the components!
There must be a more graceful way to remove this papery stuff.
THIRD PASS:


OK. I'm about to ruin this thing as more components are popping up!
I tried to see if I could melt it out, but the stuff just burns!

Well, the stuff is rubbery like a pencil eraser, and about 1/8" inch thick. I wish there was a more graceful way, but here is where I am:

Digging onward ...

Unfortunately, at this point, I've already ruined the FSU (but I don't know it yet), as that shiny thing below is the INSIDE of a chip!

It's getting dangerously close to the components ...

At some point, the chisel was far too large and impassionate, so I tried these dental picks, which were too small & personal:

Now it's getting nearer to the components, which I don't want to knock off the board (or cut a trace):

Even though it's ruined, I may as well continue to dig away, just to see what's down there:

Wow, it's great that this thread is still going. I visited a couple of years ago to find out about my blown FSU. It's nice to see progress from when I posted my photos of a resoldering fix.

The reason I'm back is that my fixed FSU has failed again as expected. However 2 years ain't too bad for an experimental fix!

Anyway, I am choosing to buy a new FSU and I am only considering brand names whether from eBay or not. From eBay I'm looking at 3 brands so far: Hella/Behr, Erst Wahle, Behr. Except for the Erst Wahle, they state in their product descriptions that they are German made and to beware of chinese copies etc. Prices are around $70 delivered.

According to Bluebee's in-depth analysis and polling of BMW dealerships, it seems the brand to go for is Valeo and possibly Sitronic, as that is what BMW supplies.

Can anyone confirm this? And a source for purchasing from would be great too!

Congrats as you have become Bee's here for life! Great find. Couple points maybe made elsewhere, but did not feel like reading every post, sorry. FSU would be at its COOLEST when fan is on high- think about it. FSU is absorbing or resisting power to the fan the least. FSU would be hottest when on lowest speed-BTW, my "auto" function never goes below three lights. That seems to be "autos" lowest setting. Manually, I can go to one or two lights for fan speed. Do not recommend using thermal conductive white paste to fill void. I would use a non-conductive silicon or just wrap entire FSU with electrical tape and leave it open. good going all and for Bee pushing for the answer as I would never have thought it repairable-it really isn't with surface mount components but never thought of just giving components room to expand. Would feel better if we could identify parts to resolder. Maybe someone touches on this. Will read all later.

Blue's life is in order again!! Can start her canonizing :-)

Originally Posted by bluebee

cn90 posted some useful information here about what some of the FSU pins actually do and how to test 'em ...

Also kraft apparently FIXED his FSU by gouging out the resin, resoldering connections, and then filling the holes with silicone!

If I understand correctly, Kraft did NOT use silicone, but instead used the white thermal conductive paste that is normally found between a heat sink and the thin mica wafer that isolates say a transistor from the heatsink so that the transistor can transfer as much heat as possible to the heatsink, yet not be electrically conductive between the case of the transistor (which is an active part of the transistor-could be base, emitter, collector) and the heatsink. A metal transistor, for example a power transistor, generally does not use the case as an inactive part of the transistor-especially not a ground) I would just leave the shaved away area "open". Who knows, you may have to go back there again. Maybe it is the heat from the hair drier that is somehow fixing the problem or the pressing of the knife as you shave away the black potting material. I am just a tad uncomfortable that we did not solder anything in some cases and we hope the cure is long-lasting. I would feel better if we could build upon kraft's great discovery and figure out exactly what is coming loose or being crushed by plastic? I like what I think cnn did (figures it would be cnn!) and remove all of the plastic potting material as possible so that using a non-conductive pointed coil adjusting tool probe (not a pencil!) with a used or SIM fan connected to FSU and see exactly where you touch FSU to get it to work again...try to pinpoint offending area. Why have any potting material put back at all? Just tape well to protect and let it breathe!

As an aside, I tried to find more information about the ELMOS 0901D chip (aka E109.01D), but it's very hard to find a datasheet on it.

Here's are sources of the chip:
http://www.exchangeic.com/Data/10901.html
http://www.jotrin.com/product/parts/T_109018
http://item.taobao.com/item.htm?id=13918440884


Here is a guy who tried to find the datasheet on the chip:
http://monitor.espec.ws/section27/topic189041.html

Translation: The controller turns the stove Citroen Evasion is mikruha Elmos 10901D. Broke brain search, help me find datasheet.
Translation: lobezik, in my opinion must be sought here: http://www.elmos.de/ At least this is just their product.
Translation: lobezik, decorated the topic so that the meaning was clear from the title. For the first time fix for you.
Translation: lobezik, you never had to use tech support? I thus find analogies opamp from AD, changing product Texas Instruments ... Write a letter to them requesting datasheet. The firm is a miserable and fresh client not throw. A mikruha still produce them!
Translation: I am sorry, I apologize. ADDED 16/12/2011 14:46
Translation: Here tree sticks, you can just write to tech support, I couple blunted. Thank you!
Translation: Received a response from tehpodderzhi Elmos, cultural refused.
ENGLISH:
Thank you very much for your interest in our products.
Unfortunately we are strictly not allowed to provide any information concerning the E109.01D to you as this product is customer specific.
Best regards,
Sina Staufenberg
staatl. geprüfte Betriebswirtin (Recht)
Translation: Here at kitaezov mentioned 10901S, but datasheets do not give.
But write this type of comparator LM711.
And here the LM711, I do not know. Do it and the body 14 pins ... frustration, disappointment
Try to look for installation, can they really pushed back comparators.

Originally Posted by olivier577

the 2 bridges are in fact 2 resistors 10 milliohm used to balance the currents between the 2 MOSFET

Does anyone have a part number on these two MOSFET transistors?

They appear to be the CRITICAL component in the FSU, as shown in the wiring diagram.


Yet, I can't find a single picture of these two MOSFETs.

The semi-conductors circled in Blues BMW diagram are not the MOSFET you are looking for information on. The Mosfet is 14 pin and what Blue has circled is something different. I think if these Mosfets were in 1000 BMW owner's hands, maybe one person out of 1000, if that, would have the skills to install in the carcass we have left after removing all the potting material. How are we determining the MOSFET is bad in any situation? Again, even with a data sheet which we will never get because these Mosfets are supposedly "special" to BMW (just like they try to hide their MAF sensor). Few would have the skills to test a 14 pin Mosfet. I believe the FSUs that have been "repaired" are again the usual "open" circuit BMW seems to like so much (can we say ABS module).

The usual mode that OEMs use to make their parts source-able only through the OEM is by taking a standard part- say a standard motor made by GE- and GE will make some standard motors (easily obtainable by anyone with a GE part number on it) and set them aside to be stamped with an OEMs part number instead of the GE part number anyone could obtain through any GE distributor. Sometimes you might source a replacement just by taking a chance and buying a motor with same frame#, same voltage, same RPM, etc., but you are never sure the motor will work like the one supplied by the OEM. I am surprised that the part number stamped on this Mosfet can be found for sale anywhere. This is not to say the same Mosfet is not out there for sale for a quarter anywhere, but the part number should not be found listed anywhere. Makes me think it is not really re-stamped with a BMW part#, but possibly the "D" added to denote sold to BMW or the 01D just added to a std. mosfet. Much ado about nothing, sorry. rant off.

This was posted elsewhere on the FSU operation:

I think the IC is a dual, high side motor driver IC and each transistor has a large emitter resistor with different values. That is the metal strips on the pins by the sets of three holes. That would give three speeds & off. Like a three way lamp with 50 + 100 Watt elements. Turn both on and it draws 150 Watts. This would explain the failure of the solder joints on the transistors since they are used in linear mode.

00 would be off
01 would be low speed
10 would be medium speed
11 would be high speed

Originally Posted by bluebee

Does anyone have a part number on these two MOSFET transistors?

They appear to be the CRITICAL component in the FSU, as shown in the wiring diagram.


Yet, I can't find a single picture of these two MOSFETs.

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.