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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Dead FET Power Transistors
I am trying to find a component part number or a schematic for a Blower
Control Board for a 1989 BMW with a 535i engine. The board has the number 275 526. L 06 stamped on it, and the Control Assembly has the name BEHR and the numbers 90 . 947 . 00 . 842, E 3264/11 and 1 388 629 . 2 stamped on it. There are four (4) blower motor settings on the control switch and only one (1) works...High Speed! Anyone that can let me know where to find the replacement FET transistors on the board would be of tremendous help. The four (4) FET's are all the same. I have looked at the transistors under a magnifying glass and can find no numbers stamped on them. I do not know if they are made by an European Manufacturer or not. I also do not know whether the FET's or N or P type or MOSFET's, etc. Any help as to the source of this information would be very appreciated. Thanks! |
#2
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Dead FET Power Transistors
You would have to know the exact required specs, and patiently search
through data sheets to find the appropriate replacement. If these transistors are blown, you must also find the cause, and fix that as well. Maybe the device that is driving or loading them is also faulty, and this is the reason for the failure. As for automotive parts, the manufactures use their own house numbers on the parts, and also have many of them custom made for their applications. The dealers normally service at the modular level. They very rarely do anything at the component level. This is why your dealer most likely will not be able to supply these parts individually. -- Greetings, Jerry Greenberg GLG Technologies GLG ========================================= WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm ========================================= "Robert L. Milton, Sr." wrote in message om... I am trying to find a component part number or a schematic for a Blower Control Board for a 1989 BMW with a 535i engine. The board has the number 275 526. L 06 stamped on it, and the Control Assembly has the name BEHR and the numbers 90 . 947 . 00 . 842, E 3264/11 and 1 388 629 . 2 stamped on it. There are four (4) blower motor settings on the control switch and only one (1) works...High Speed! Anyone that can let me know where to find the replacement FET transistors on the board would be of tremendous help. The four (4) FET's are all the same. I have looked at the transistors under a magnifying glass and can find no numbers stamped on them. I do not know if they are made by an European Manufacturer or not. I also do not know whether the FET's or N or P type or MOSFET's, etc. Any help as to the source of this information would be very appreciated. Thanks! |
#3
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Dead FET Power Transistors
Robert,
Unfortunately, I have to agree with Jerry, it is not likely that you'll get a spec. Your best bet, besides paying BMW their price is to go to a junk yard (aka Automotive Recyclers) and get another module. You can find several that specialize in BMW's in the BMW car club of America's (BMWCCA) magazine "Rondel". Regards, Tim Schwartz "Robert L. Milton, Sr." wrote: I am trying to find a component part number or a schematic for a Blower Control Board for a 1989 BMW with a 535i engine. The board has the number 275 526. L 06 stamped on it, and the Control Assembly has the name BEHR and the numbers 90 . 947 . 00 . 842, E 3264/11 and 1 388 629 . 2 stamped on it. There are four (4) blower motor settings on the control switch and only one (1) works...High Speed! Anyone that can let me know where to find the replacement FET transistors on the board would be of tremendous help. The four (4) FET's are all the same. I have looked at the transistors under a magnifying glass and can find no numbers stamped on them. I do not know if they are made by an European Manufacturer or not. I also do not know whether the FET's or N or P type or MOSFET's, etc. Any help as to the source of this information would be very appreciated. Thanks! |
#4
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Dead FET Power Transistors
"Robert L. Milton, Sr." wrote in message
om... I am trying to find a component part number or a schematic for a Blower Control Board for a 1989 BMW with a 535i engine. The board has the number 275 526. L 06 stamped on it, and the Control Assembly has the name BEHR and the numbers 90 . 947 . 00 . 842, E 3264/11 and 1 388 629 . 2 stamped on it. There are four (4) blower motor settings on the control switch and only one (1) works...High Speed! Anyone that can let me know where to find the replacement FET transistors on the board would be of tremendous help. The four (4) FET's are all the same. I have looked at the transistors under a magnifying glass and can find no numbers stamped on them. I do not know if they are made by an European Manufacturer or not. I also do not know whether the FET's or N or P type or MOSFET's, etc. Any help as to the source of this information would be very appreciated. Thanks! Maybe a moot point, given the other answers to your question, but if there are no identifying markings, how do you know that they are FETs? I totally agree with the others that piece parts such as those transistors, are virtually unobtanium, especially from the manufacturer. If you're intent on finding replacement transistors, perhaps your best bet would be to find a copy of the shop service manual for your car. Be sure that you get one that has the complete electrical schematics and parts lists. There may be a partial schematic in there, but in all liklihood, there won't be enough detail to give enough info to identify the components. Go to a junkyard and find the complete module. That's probably your least painful route. -- Tweetldee Tweetldee at att dot net (Just subsitute the appropriate characters in the address) Never take a laxative and a sleeping pill at the same time!! |
#5
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Dead FET Power Transistors
First is the fan on or off all the time
Next is it a FET and is there flyback diode across it they can also short. Does the voltage that controls the FET work properly (might not be the FET) If it is the FET find out the starting current for the fan and check with Digi-Key or other supplier and pick a power FET that will handle that current, for a car the voltage is a lesser concern but pick at least a 100V unit. Remember to put a flyback diode across it if there isn't one and a transient voltage suppressor as well 24V would be good. "Robert L. Milton, Sr." wrote in message om... I am trying to find a component part number or a schematic for a Blower Control Board for a 1989 BMW with a 535i engine. The board has the number 275 526. L 06 stamped on it, and the Control Assembly has the name BEHR and the numbers 90 . 947 . 00 . 842, E 3264/11 and 1 388 629 . 2 stamped on it. There are four (4) blower motor settings on the control switch and only one (1) works...High Speed! Anyone that can let me know where to find the replacement FET transistors on the board would be of tremendous help. The four (4) FET's are all the same. I have looked at the transistors under a magnifying glass and can find no numbers stamped on them. I do not know if they are made by an European Manufacturer or not. I also do not know whether the FET's or N or P type or MOSFET's, etc. Any help as to the source of this information would be very appreciated. Thanks! |
#6
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Quote:
The IC is a LN2903 - Dual differential comparator - http://www.fairchildsemi.com/ds/LM%2FLM393.pdf |
#7
Posted to sci.electronics.repair
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Dead FET Power Transistors
How do you know the FETs are bad? Did they explode?
FETs tend to fail shorted, so the more likely symptom of a bad FET would be that the fan runs at nearly top speed on all settings. I'd go check out the on-line junkyards if you can lower yourself to do so. |
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