R75/6 Diode Board

Hoff · Sep 24, 2021

Bike is a R75/6 (1976)
Bit of a numpty question.
The cable with the three wires running from the stator to the back of the diode board has definitely seen better days so I decide to change it. Followed the procedure in my Clymer and removed cable and diode board with no problem. My question is I removed the cable connector (two blue wires) from the right hand side of the board (right side of the picture) and am sure they were connected to the horizontal connector but just asking if someone can confirm for me and is the vertical connector not used?
Picture of the diode board included.
TIA
Paul
:blast

As an extra question is there an easy way to test the diode board, the bike was charging when I last rode it so I hope it is ok !!

Gelandestrasse · Sep 24, 2021

Hi Hof. I've just tonight re-installed my diode board on my R90S rebuild. It doesn't matter which terminal you use to put the blue wire on.

Hoff · Sep 24, 2021

Many thanks

Hoff · Sep 25, 2021

Re testing the diode board all done and ok just needed to have my meter in diode test mode and not continuity mode.

Gelandestrasse · Sep 26, 2021

Hoff, here's a picture of the blue wire(s) in the back of the diode board.

I've opted for solid mounts (heat sink) and also kept the earth wires (grounding) for a belt-and-braces approach to diode board potential issues.

Hoff · Sep 26, 2021

Thanks for that.
My diode board was mounted directly to the timing chest cover with no mounts of any kind. The four posts it bolts onto are blind holes with the lower two slightly longer the the top two (see picture below). It was like this from when I got it so is this set up going to give me problems? Is this a set up from another bike?
Mine was an ex Police bike does this help?

Hoff · Sep 26, 2021

Found this link and it mentions earlier engines with board mounting pillars cast as part of the engine case. This would appear to have what I have hope I am right !!

https://www.angelfire.com/ca2/thunderchild/diodeinstall.html

Gelandestrasse · Sep 27, 2021

Hoff, you have an early engine - the same as my 1973 R90/6. No earthing or heatsink issues. Back then (according to Snowbum) they had some duff diode boards which had poor soldering. They wen as far as rubber mounting them on later models (modifying the Timing Cover) which isolated the boards from the Timing Cover so heat then became an issue. They had little wires (as I pictured) to give earth continuity. None of this complication with yours, though. I think the final stage was solid mounts; Snowbum advises to avoid stainless steel solid mounts as SS is not a good conductor. Mine are SS so I put the wires back in.

Hoff · Sep 27, 2021

Hi Tim
Cheers for that it confirms my setup is fine just waiting for some new alternator brushes and a new stator to diode board cable - on way from Motobins.
Many thanks for the help

R75/6 Diode Board

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