I previously had issues with the speedo which were resolved in this previous thread:
https://www.k100-forum.com/t18500-broke-my-speedo-fixing-my-speedo-solved

At the end of the journey, it worked but I had put it back together without a piece of foam that backed the odometer. 

So I pulled it apart again, reinserted the tiny piece of foam and put it back together again and blam. No more working. Speedo is completely dead again but everything else works. 

I pulled it apart again and put it back together again but this time i did not put the back housing back on (to speed up testing). Now it works. 

Put the housing back on and try again and it doesn't work. 


What the hell is happening here? My best guesses are that either there is a poor contact between the two plugs that plug into the back of the cluster which are able to make contact when the housing backing isn't on OR something is being shorted when the housing is back together. 

It should also be noted that the pins coming out of the device, 3 of them are broken off their solder but are still making contact when it's put together. My next step was going to be to solder these back together again though I already deoxited them so that they were not having corrosion issues. 


I'm confused as to why it worked once, then stopped. 


At the end of the last post, I now have at my disposal the following tools:
- Multimeter. 
- Deoxit.
- Copper tape with conductive adhesive.
- Silica packets for moisture. 

I don't have a 12v power source to test things though other than the actual battery, nor the knowledge (yet) to know what to do with testing that. 

Photos attached are: Arrows pointing to the loose pins & a circle showing the foam piece I put back together prior to the speedo stopping again. 

I'm certain that this will wind up being just an unrelated poor connection but any insight is well appreciated as I'm eager to get riding. 

ark100 wrote: It should also be noted that the pins coming out of the device, 3 of them are broken off their solder but are still making contact when it's put together.  I'm confused as to why it worked once, then stopped.

It worked once because tenuous contact between loose electrical connections is subjected to the whims of pressure, heat, gravity and vibration. Sometimes they align to make contact then they’ll be jostled or subjected to temperature change in ways that create loss of contact, then will be affected again by movement or temperature and connect again.

A similar condition is found in house lighting switches where ground screw or wire nut connections are improperly made. Sometimes they work; sometimes they don’t. Rarely are they dependable for the long term unless the connections are secured.

Hope and despair alternately rule until successful repair or replacement occur.

ark100 wrote:It should also be noted that the pins coming out of the device, 3 of them are broken off their solder but are still making contact when it's put together. My next step was going to be to solder these back together again though I already deoxited them so that they were not having corrosion issues.

The solder is there to make the electrical contact.  If there are visible breaks in the solder joint you DO NOT have electrical contact.  It doesn't matter what you do to clean the connection the reliability will be crap.

Solder them properly before you screw around with anything else.

Soldering those pins: scrape off an area of the plating until the brass shows through. If you don't, you'll find it near impossible to get the solder to flow without damaging the plastic. Use a high lead content multicore solder and a 25watt or 30watt soldering iron to minimise heat transmission onto the plastic PCB backing. Re-fixing those pins is a RRPITA; trust me about that.

Hot damn, that was a pain in the ass to solder but on rebuilding it's still not working. I think I've got no choice left but to try source a part (the pin bit) or something) .

you will have to measure some stuff whilst apart 

a common issue is that the 4 pin flexible circuit that connects to the speedo amplifier board ... also goes on to the 3 pin connector at the motor ...top of the meter 

that connection does fail and may need to be soldered at the pins 


you can also solder as dai says directly to the pins on the main input connector , then wire to the 4 pin and then to the 3 pin  to make it all work 

which i have done a couple of times