I am aware of that. It looks like it ties the two collectors together. But does it go to the contact that connects to the fuse? The main point is "do the collectors (center pin on transistor) connect to the 12 volt input to the module"?
Thanks, tm
I have tried to repair the FSU for BMW e46 by replacing the two MOSFET tran sistors with equivalent: IRF3205 (and even two more powerful) but it seems they cannot do the job due to other electronic component which i cannot fig ure out. Even though there is a change on G -gate the transistor won't chan ge the flow ..there must be something on the Base or Collector ... I'm stun ned cause i tried repairing two of them
ansistors with equivalent: IRF3205 (and even two more powerful) but it seem s they cannot do the job due to other electronic component which i cannot f igure out. Even though there is a change on G -gate the transistor won't ch ange the flow ..there must be something on the Base or Collector ... I'm st unned 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?
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
Do you get many on topic comments on a home repair list?
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.
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.
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.
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 ?
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?
The fsu from behr doesnt have that resin and it was easy to open.the new mo dule has the transistor on a copper plate to make the heat transfer fast bu t the contact with the aluminium its not so good.I did lost the waranty whe n i did this,but i'm not giving up in building an fsu from scratch.I have s ome pictures of the fsu.
miercuri, 5 februarie 2014, 01:43:49 UTC+2, snipped-for-privacy@gmail.com a scris:
module has the transistor on a copper plate to make the heat transfer fast but the contact with the aluminium its not so good.I did lost the waranty w hen i did this,but i'm not giving up in building an fsu from scratch.I have some pictures of the fsu.
And this is the heatsink i want to use and maybe add a little fan which will run when hvac comes on but i need to find a +12v from hvac control
Someone had scoped the whole board, and it was DC voltage everywhere (according to that reference). It's pretty clear there is no PWM.
The 16-pin surface mount chip seems to be a automotive temperature compensated voltage regulator with a huge voltage range, according to a lookup of the part number on it.
Here is the Elmos 10901D chip of my FSU as I cut it open today.
I wish there was a way to get rid of that heavy fibrous plastic goop! (What is that black fibrous tough stuff anyway?)
I have had good luck removing the stuff used on motorcycle voltage regulators that were potted soaking in MEK Methyl ethyl ketone (spelling?). Potent stuff. Use outdoors and keep your hands out of it. WW
I don't know what it actually is but at work we desolved a potted firing system for a boat motor with something called OCP. Really stinks. Don't think I would want it in a car after it was used.
Yes, I hear what you're saying. I assume it's being used like a switch, all the time being switched on and off in a PWM fashion, like a light dimmer. But while going from off to on, in the middle, it will generate more heat. That's why electronic light dimmers get warm too. And I guess if something is wrong with the motor, like your bearing example, it could generate more heat in the FSU. I guess a way to look at it is like what would happen if you put a 1500W load on a triac based AC light dimmer rated for 700W. At full power, it would probably be fine. At half power, it could get so hot it fails.
If the bearings are going bad or there is some other reason the motor
Not so far because there isn't an easy way to do so. I don't have a clamp on DC ammeter and with the connector they use, no way to get something into/onto the circuit. It hasn't blown the blower fuse. I guess I could stick the wire with a pointed probe, but even that isn't easy because there isn't much access to the cable.
There is one more avenue being pursued. This car uses a cabin air filter and it's fairly dirty and needs to be changed. Thinking that might have some effect on it, but on the other hand AFAIK, it only filters the outside incoming air, which is like 20% max and the dash controls allow that to be shut off, or automatically controlled, etc. So I would think the blower should run fine with just the cabin air, especially at lower speeds, but who knows. So one of those is on the way.
After that, I think next is going to be to get another FSU, from another manufacturer and try it. The BMW one was $125, there are Behr ones available for $45. As you can see from the thread, these things are poorly designed and have a high failure rate. They've been around since 2000 and they still all suck and fail. Folks can't even agree if any of the various manufacturers are better. They have changed the design. The original ones had less heat sink pins, but they were larger. New ones have at least 2X the pins, like 40 of them, so clearly they've changed the design because of heat issues. Because they all suck is why the guys here have been trying to reverse engineer it and see if they can do something to make it work. I think just a larger heat sink would probably solve it, but no easy way to do that I can see.
Still you think a new one from BMW would work out of the box, but who knows. The other sad news is that to get to the blower requires removal of the whole dashboard :(
If you want to see a pic of what one looks like, just google BMW FSU.
My electronic assembly company built the electronic control unit for BMC Chopper of Bend, Oregon. Now defunked. We used two-part black epoxy that took 24 hours to completely cure. When applied it was water thin. Had to prep the box with RTV to keep the potting from running out around the connectors.
Paul
Well, if that's the case, it would explain why they run so hot.
What lookup? No one has a datasheet on it. The most I've seen is the garbled Russian traslation of God knows what that someon posted earlier in the thread that says that's what it is.
It doesn't appear to me to be a standard part. Elmos is a large manufacturer of ASICs and that's probably what it is, ie a part done for whoever made the original. That would explain why there is no datasheet. But if that's so, an interesting question remains. How are all the various companies that make this thing getting the same part? If you make an ASIC with a semiconductor company, then unless you let them sell it to someone else, it's yours exclusively.
Good pictures.
It looks like the chip, the transistor and a bunch of caps, resistors, diodes. Anyone know what that funny looking copper strip is with glue or whatever under it is?
I would think that adding a little fan to the heatsink might be the most productive approach. If you can find a power source that's on when the HVAC on that would be great. But you could also power it from anything that has
12V when the ignition is ON, which could be a lot easier to find. Any chance of tapping into any of the blower airflow to cool it somehow? And is there even room in there for the additinal fan? Where the part goes under the dash, I can't tell what room there is behind it, but I would doubt there is enough for a fan.One difference I see with your new part and Sitronic one from BMW is that your Behr one uses an aluminum housing all around the part, while the BMW part uses plastic. I noticed that difference in some of the pics before, but couldn't tell which ones were all aluminum and which just had aluminum for the heatsink. The all aluminum should be better because it can help conduct more of the heat away.
Another perhaps minor point. IDK how the thing is fastened into your car, but on the X5, it kind of snaps in, but from the removal instructions, there are supposed to be two small bolts that hold it down. The one here had been replaced previously and had no bolts. I can see why, given where it goes it would be hard to get to the bolts and the clip seemed to hold it well enough. But.... If it's bolted to metal and it's all aluminum like yours, that would help take some more of the heat away. But then it looks to me like most of the ones out there have plastic frames anyway, so in that case I don't think bolting it down is going to make much difference in transfering heat, as plastic doesn't conduct that well.
I also don't know how productive figuring out what's hooked up to what on that board is going to be. No one has been able to find a datasheet on that Elmos chip. No one is even sure what it really is. If the intention is to build a new design, my approach would be this. There are only 5 wires to this FSU.
12V GND Signal ( very small wire) Motor + Motor -The missing piece here is what's on that control signal wire that sets the speed? If I was going to make a new design, I'd put a scope on it and find out if it's an analog signal, digital, etc. If it's just analog and varies with the set speed, then you can design a new circuit. Of course getting it into the right form factor, etc is going to take a lot of work. IMO, it's not worth it.
Oh, and regarding that single wire control, they use a similar single wire to control the variable speed auxilliary fan for the radiator. That fan has electronics in it too that can vary the aux fan speed, based on a control input. Simnple on/off like a billion other cars have was too simple. And it's in the worst place possible right next to the radiator.
The reason I bring that up, that fan fails frequently and can drain the battery. The car here, the fan stopped working, but the AC still works fine except when stopped in traffic. I was worried about it draining the battery, which they are known to do when they fail. So, I unplugged it. It's just 3 wires, 12V, gnd, control. And..... the AC no longer worked at all. The only way I could explain what was happening was that somehow the HVAC control knew the fan was disconnected, leaving me to wonder if that single wire control to it was bi-directional. IDK why anyone would design it that way, not 100% sure it's done that way, but thought I'd mention it in the sense that the single wire into the FSU might not be so simple.
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