Hi
My speedo shut down approximately eight years ago. Tachometer was fine.
Decided to try once again to open the gauge cluster. 
I looked at the long thin board (signal amplifier) and didn’t notice anything unusual. I decided to check the other side of the board and noticed there was a scorch mark and the copper tracks were a bit of a mess.
Turned the board over and noticed a very faint burn mark underneath a electrolytic capacitor the 10μf next to the green one.
I replaced the capacitor and applied deoxit to all the pins.
The speedometer and odometer now function correctly.
Anyone who has issues with their Speedo, I suggest a careful check of BOTH sides of the board.



Cheers

Gabriel

great solve 

good luck mate

Thanks. 
The fixed location of the board at the bottom of the instrument gauge and the close proximity of the copper tracks makes me think moisture in the instrument gauge over the years corroded the tracks.
I’m very happy that it’s now working. The self cancelling indicators also work.
There was information from this forum and Motobrick which helped me to resolve this issue.
We are lucky to have access to this forum and the many members who volunteer information.
Next agenda item is my rear brake master cylinder......ouch....

Nice job repairing your speedometer! 

As far as the rear master cylinder, there are threads here and at Motobrick.com that describe replacing it with a ChiCom unit for under $20.  If you wear a mask and gloves while you handle it, you can get it on your bike without dying from the Covid-19 in a couple hours.

Good that you found the problem and were able to fix it.

More and more, these types of things are going to happen to our electronics. Capacitors have a useful life and the age of the electronics in our bike means that component failures, especially capacitors and transistors, will be on the rise. The most likely cause of your faulty speedo board was that the electrolytic cap shorted internally. That would cause the scorched PCB.