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Mini Speedo - Diode wiring problem

4277 Views 10 Replies 5 Participants Last post by  sampobp
I got my mini speedo from Mike XS. Started the wiring with the help of psasac's wiring diagram below (huge help). Saved the diode wiring for last.
I bought the only diodes that were even close at Radio Shak. 50V 3A. I got them solderred in, hooked power back up and tried it out. Everything works beautifully except for the "winker" (that's what the wiring diagram that comes with the speedo calls it).
I noticed that while solderring the diodes, they got really hot. Could that have fried them?
Was my diode selection wrong? Are they just not allowing any current to pass?
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Diodes conduct in only one direction, if you get them backwards, they wont work.
Just make sure they look like the diagram - the ends with the two white bars are connected together and to the indicator lamp (yellow wire) - the opposite end of each diode to each of the signal wires.
The other wire of that indicator lamp (yellow/black) needs to be connected to the common ground wire
Wired them in just like the diagram shows. A diode connected to each of the green wires in the harness and both connected to the yellow wire. Band of the diode on the speedo side. Yellow with black stripe connected to ground wire.
wouldn't work so I reversed them. same thing.
No point in reversing, they definitely have to go in the direction indicated i.e. white bars to the lamp.
Those are pretty heavy duty diodes and I would doubt if you cooked them, and to do both would be extreme.
Did you validate that you have 12V to each wire at the diode?
You can test the basic operation of the lamp and the negative side wiring by just connecting momentarily one or the other signal wire directly to the yellow?
If that doesn't work, then possibly either bulb blown or ground not connected properly.
To validate eliminating the signals altogether take a 12V source and connect to the yellow (length of wire just touched to the battery + momentarily)
But if lamp works with test (direct connection from signal to the yellow wire) then yes, diodes are blown.
You can also test the diodes with your DMM - many have diode setting but you can also use resistance check if not - you will get reading one direction but not with test leads reversed. If you have diode setting, it will read 0.6V in forward direction.
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That gives me a few ideas. I'll let you know what I find out.
Thanks for the input.
Finally got back to this. You were right. Bad ground.
Good ground and all works well.

Can't beleive this speedo is actually more acurate that the OEM.

Another question though. Why would I get one side of the turn signals blinking fast now? Left side is fine. Right side is really fast on and off.
Have you lost a bulb on the right side? (or is wattage slightly lower in one bulb perhaps?)
All bulbs are the same and are OK. Funny thing, this only started after I did the wiring for the speedo.
Finally got back to this. You were right. Bad ground.
Good ground and all works well.

Can't beleive this speedo is actually more acurate that the OEM. QUOTE]

I've got a MikesXS mini speedometer - it is only off two miles per hour, compared to four or five with the stock. Nice little pieces of equipment too!
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I did the mini speedo swap. Wiring with diodes.
Everything works great with the idiot lights before I start the bike. (Bonneville 2006)
While bike running the blue idiot light for beam and the green for turn signals stop working. I turn the bike off and they all work fine again. Am I running some current issues while bike is running? Could this be due wrong size of Diode? I am running 2 pcs of 20 ohm’s diodes.
One for each green/white and green/red.
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