The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: studebaker04 on July 10, 2012, 09:39:09 PM
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Hey guys,
I turned my bike off today 1982 r65. When I took the key out the gen light turned turned on and won't go off. Any ideas?
Thank you.
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Failed diode in the diode board, is my first guess .
You may want to disconnect your battery, or it will be discharged overnight .
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It may be a bad diode in the diode board, though there are some more "subtle" failures which could also cause this to happen with the key switch off. The key switch itself should turn off power to the gen light/voltage regulator/rotor excitation circuit with the key "OFF". If you are able to turn off & remove the key, and have the light(s) remain on (is it just the GEN light, or do other dashboard lights work?) it is possible that there may be something faulty with the switch, or it hasn't been wired correctly. Has any work been done to the bike recently?
Does the light ever go off after you've started the bike and get the revs over 2000 rpm or so? Or, perhaps the battery is pretty much drained by morning?
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when i turn the key to the on position the gen light turns off the neutral and oil come on. the gen light is the only thing that stays on. can I disconnect the diode board?
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Update battery dead. Can I replace the whole gauge assembly my speedo does not work anyway.
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Update battery dead. Can I replace the whole gauge assembly my speedo does not work anyway.
Are you saying the problem was caused by a dead battery or that your battery is now dead?
The GEN lamp and circuit is more than just an idiot light. The bulb is a key component of the exciter circuit that is required to get the alternator to begin charging the battery. If you have a burned out GEN bulb, your battery will soon go flat.
To answer your question; you would need to add a resistor into the GEN lamp circuit to fool the alternator into going to work. Snowbum has the details on how to do it. I have installed these safety circuits on both my R65s.
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The diode board, is under the front engine cover .
It serves the same purpose that the diodes in your auto alternator do, they are just seperate and can be easily changed .
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I agree that it must be the diode. Does any one have a link to how to repair it?
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It's a remove and replace type item .
Here's a link to what it looks like .
http://www.euromotoelectrics.com/BMW-R-Airhead-Diode-Board-12-31-1-244-06-p/boalt-rect063.htm
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Good deal thank you. Is this the best way to go?
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If you know how to check diodes, it's best to confirm the diode board is the problem .
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I am some what handy. Is it hard to check diodes? Is there a way I can repair the board?
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You need a multimeter, to check the individual diodes .
The diode board is pretty much a remove and replace item .
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For a full dissertation on the diode board, it's care and love and discipline, read Snownum's full thesis.
http://bmwmotorcycletech.info/
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I am some what handy. Is it hard to check diodes? Is there a way I can repair the board?
That's certainly what I'd do or at least attempt. There's nothing special about them they are just diodes of a certain current rating. One problem might be the grey paint on the board.
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Update, Board removed. I can see the problem. Something tells me I just need to buck and pay. Does any one have ideas on how to avoid this in the future?
Thank you all for your support and dedication to helping a fellow airhead in need.
Aaron
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Unless, this was caused by removing the front cover of the engine and touching the diode board in the process while the battery cables were still connected, not much you can do to prevent it .
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Ya, that location at least seems like the usual/common right upper side spot that usually gets shorted out when removing the cover. But, it could have just been a marginal solder joint or failed diode of its own With the amount of current needed to blacken and separate those heavy traces on the board, there was definitely a substantial short for some time. I'd definitely get a new ( or good used) diode board assembly, as a number of the diodes , and traces may have been compromised. You would have to take them all out and test them and know how to spot one that is not completely ruined yet - too much effort and potential for recurring faults, IMHO.
Rick at Motorrad elektrik will set you up with a nice aftermarket unit - I have one in my R65LS - but, you'll have to contact him quickly cause he'll probably be headed to the rally in Missouri very soon!
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could this have anything to do with my turn signals not working well?
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What are turn directionals doing ?
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I used a red dielectric paint on the back side of the diode board. This paint is used to assist the insulation of electric motors and generator windings. It is thick and is designed to work even hot. You can get some at electrical supply shops.
It is possible to solder a insulated wire from one point of the diode board to the other bypassing the damage in the board but you must remove the diode to check and replace if shorted. It probably is better to start with a new one and and reinsulate once factory insulation starts to flake off.