What are the diode type ?

[georgesgiralt]

Hello !
I've been given a dead diode board with a couple of the big diode fried (never remove the front cover with the battery cables attached...).
I would like, if possible to fix it.
So does someone know what kind of diode are used in this diode board ?
As far as I know, they are three types : the big one are either anode to the box or cathode to the box, and there are small "plastic" diodes for the rotor output.
Many thanks in advance !

[Barry]

They will just be silcon diodes the only difference being current rating. Diodes are always marked with a line towards one end to indicate the cathode. Power diodes and I'm guessing they may be 30A on the diode board do not always come in the simple cylindrical shape and you would have to see what the ones on your board look like before seeking for replacements.

[montmil]

Snowbum has an extensive article -and, with da 'bum, are there any other kind- on repair of diode boards. Check him out. pack a lunch.

[Barry]

Found the answer courtesy of http://jhau.maliwi.de/mot/r-elec.html#diodes

Motorola 1N3660 (cathode to case) and 1N3660R (anode to case), which are rated 100 V and 30 A at 100 °C.

[georgesgiralt]

"Motorola 1N3660 (cathode to case) and 1N3660R (anode to case), which are rated 100 V and 30 A at 100 °C."
Which are unobtainium since a long time ago (Motorola stopped bipolar semi conductors years ago).
I think I'll try to get a DO208 30A/100V replacement and hope it will hold 100°C ....
Will keep you posted !

[georgesgiralt]

So, none of the usual suspects from which I seldom buy electronics component can sell any DO208 diode with a decent rating.
I think I'll bring the diode board to the waste ....
Or if any of you has a dealer ?

[Bob_Roller]

Why not save the diode board, you still have good diodes there .

May be able to use them if the diode board you are currently using goes bad .

At least in North America, I think I would purchase an after market diode board, if the ones in use fail .

http://www.motoelekt.com/charging.htm

http://www.euromotoelectrics.com/BMW-R-Airhead-Heavy-Duty-Diode-Board-p/boalt-rect063edl.htm


I'm surprised the diode board on my '81 R65 is still working, I installed two 55 watt PIAA 40 driving lights about 10 years ago and use them all the time, the charging system is probably near it's maximum limit of output most of the time .

[nhmaf]

I wouldn't throw it out - there are usable parts still on it that might save you - or someone else, in a pinch.  Plus, it is still possible, with some searching, to find some of those old obsolete diodes - here are some of them on ebay (US)....
http://www.ebay.com/itm/1N3660-MOTOROLA-w-RED-LOGO-POWER-RECTIFIER-NOS-/390477412463?pt=LH_DefaultDomain_0&hash=item5aea44786f


http://www.ebay.com/itm/New-Motorola-1N3660-Radio-Transistor-NIB-audio-spare-parts-NOS-Diode-Rectifier-/121084074418?pt=LH_DefaultDomain_0&hash=item1c312c59b2


Not a good price for the reverse case connection part, as expected -
http://www.ebay.com/itm/GENERIC-D1N3660R-FNFP-D1N3660R-/221078918862?pt=BI_Control_Systems_PLCs&hash=item33795496ce

[georgesgiralt]

Yes, I've seen those. Yes I can find some from sources near my home, but :
The ebay one are correctly priced and shipping them to France is costing the price of a new diode board.  
Those sold by electronic dealer locally are over rated at 600V and priced accordingly, so this also make the repair not economically feasible.

[AlfromNH]

If you don't want the board, put it on eBay. Someone will probably buy it for parts...

Edit: better yet, put it on the the trading post here. Surely one of our resourceful members would like to have a few diodes on hand  

[georgesgiralt]

Alas at least 5 on the 6 big one are dead (plastic has melted for 4 of them and the fifth has it's box deformed to the point it is not held on to the radiator any more...  I did not test the last one, but I doubt it is still good. It would be a miracle it has survived.
The board miss two small diodes and the other may be questionable (I did not test them).
The whole thing looks like someone used the board as a soldering rod...
So even for free it is not a good deal ;-)