Cross-connected my battery!

[Hunsta]

Personally I`d call an Excorsist. Sorry couldnt resist that

Excorsist?   Say, what?

ex·or·cist
noun
1. A person who expels an evil spirit or demon.
2. In some religions an exorcist is a person who is believed to be able to cast out the devil or other demons. A priest, a monk, a healer, a shaman or other specially prepared or instructed person can be an exorcist.

dic-tio-nary
noun
1. A reference book containing an alphabetical list of words with information about them.

Sorry. I couldn't resist that, either

Monte

I would say Hunsta does not use a browser that incorporates an automatic spell-checker, or he simply ignored it.

Friends don't let friends use Internet Explorer...

Hey I come from a rural town in OZ. We gotta rub 2 Koala`s together to get the static electricity to run my computer. To me a spell checker was my 6th grade teacher. But nice of you guys to point out my shortcomings.  

[montmil]

This post is also in the Trading Post section:

WTB Diode Board

While working through the diagnostics and double checking, I'm pretty sure at least one of the two smaller diodes in the diode board/rectifier of the 1981 R65 is toast. I plan to swap in the board from the 1983 R65 as a confirmation test but in the meantime, I'm in the market for a replacement used diode board.

If any R65ers have one laying about and gathering dust, please PM me or email. Thanks.

Monte Miller
montmil@verizon.net

[montmil]

Had to lay off the R65 for a few days. Pesky days when ya have to go to work or spend the quality time with others.

Here's the diode board as removed from the '81 R65. Any guesses as to where that toasty smell might have been coming from? Looks bad. Smells bad.

Another addition for the loaded shelf in my shop; labeled, Offerings to the gods of BMW.

Monte

[Barry]

Snowbum came good for you there Monte.  Diodes shorted to earth on reverse polarity so they will have pulled a very large current and fried.

I suppose that grey paint is meant to insulate the board from inadvertent shorting out when the front cover is being removed but it must make any soldered repairs difficult. Could new diodes be soldered in if you could get the paint off or is the board itself damaged.

[montmil]

Snowbum came good for you there Monte.

Could new diodes be soldered in if you could get the paint off or is the board itself damaged.

Da 'Bum does know his stuff... Luckily for thousands of Airhead owners.

I would imagine new widgets could be soldered into place but I have a good used board on the way. Unsure how easy/difficult it might be for me to identify and source the needed diodes. That sorta stuff gets pretty deep for me. :-?

Monte

[Rob Valdez 79 R65]

Lots of diode boards have been repaired by replacing the large diodes - at least that is what I have read over the years.  The diode part #'s shouldn't be that hard to find.
I'm not so sure about the small diodes, but I'm confident that what one man made, another man can fix.

Diodes need a heat-sink placed between the diode and the soldering point, and it seems to me that these diodes are flush with the board - so I don't know how they accomplish that.
Too much heat from the soldering iron will quickly destroy the internals if care is not taken.

Besides the shelf - someone may pay you $10 or $20 for the board so they can repair it to keep as a spare or to sell.  That would be someone that has done this before, obviously!  (not me.)

[donbmw]

Since you need and new diode board I would install the Omega diode board instead of the stock board. I have been using on close to 8 years now on my R90. I also have the 450 watt alternator on the R90 and on my 82 R65. I need to do some looking I know I have one stock board and may have another one or two in some spare parts I got from a freind when I bought the 80 R65. I will look over the weekend and let you know.

Don

[montmil]

It's alive! Insert video here of me doing the Happy Dance...

These old Airheads are tough rascals. Even my brain seizure couldn't keep the R65 down for long. If work had not gotten in the way, Old Blackie would have been out on the street much sooner.

The photo tells all. The two black-ish areas are where the voltage spike cooked a few diodes and then burned through the copper circuit strips. It's also the source of the stinky smell that lingered as a reminder of my error. Didn't even bother thinking about a diode board repair attempt. The diode board/rectifier unit just does not lend itself to a DIY fix.

No harm to the wiring harness. Amazing, that.

My thanks to all the R65 dot org'ers and my friends in the Airhead Beemers Club who offered advice, parts and sympathy.

A few lessons learned and in no particular order:

1. As to battery jumper cables, here in the USofA, red is positive and black ain't. :DD'oh.

2. An easy way to increase the charge to your battery is to remove any paint on the four studs where the diode board mounts. Clean off the paint, add a smear of dialectric grease and your battery will get a better kick.  Also check for any paint transfered to the diode board mounts locations.
   If you want more, remove each timing case screw -one at a time- and clean paint off the case where the screws snug down. This is a bit time consuming but does improve the grounding. BTW, in the way-back days, BMW had a service note to dealers regarding the diode board/paint/grounding issue and would do the cleanup as a recall.
   Good grounds are vital with electricity, coffee and divorces.

3. My oil pressure warning lamp would remain dimly lit even with the ignition off. Power bleeding into the electrical system due to the damaged diodes was sending a little bit of power to the OP switch. No more of that , either.

4. I think the gray paint on the diode boards serves as protective covering; keeping potential corrosion at bay. The paint would definitely make any efforts at repairs a challenge.

5. The voltage regulator seems unaffected by all this.

I suppose this will close out this thread. It has actually been a good learning experience in spite of my momentary lapse.

Monte