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Discussion Starter · #1 ·
Hi, does anyone have any experience with these Chinese ebay speedometers. I've wired everything up correctly but I'm not getting a reading for the revs or speed (the whole point I bought it).
I have seen one other person have issues with the revs and they just wrapped the wire around the ht cable and that worked apparently. So will give that a go.

As for the speed, I'm lost. The sensor is getting power but when I pass the magnet past it I get nothing.

Anyone a bit more clued up than me? Or am just looking at some cheap faulty electronics

 

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Ive been looking at these Chinese clocks for a while and it would seem that there can be problems with the electronics, its something to do with the way the signal is picked up for the rev counter, people have used the bikes original wiring or signal and it doesn't work, I cant find the post that refers to it at the moment just try google it may find it, I'm using a tablet and this forum search function doesn't work on it , as for the speed it seems that spacing of the sensor and magnet are crucial and also there is reference to the number of magnets used, if the problem cant be resolved then it would look like the clocks are no good and some sellers have sent replacements, I think quality control is a bit hit and miss at the factories.
 

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Discussion Starter · #3 ·
Thanks for the reply gazmo, I knew I'd be taking a bit of a risk with these cheap speedos. But in fairness the eBay seller has passed the question on to their supplier (or so they say). And have said there is a 1 year warranty.

I did find this video which shows the wire wrapped around the ht lead
https://youtu.be/CFLCbqfrgE8
I'll leave it here, hopefully someone else will make use of it too.

As for the sensor, I haven't actually mounted it on the bike. I just swiped the magnet back and forward over the sensor. Maybe that's where I went wrong.
 

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Discussion Starter · #5 ·
Update:

I just tried coiling a wire around the spark plug cable like in the youtube vid.
first time around i forgot to plug the lead back into the sparkplug like the dumbass i am haha. but it worked and i got a reading on the rev counter.

but when i realised what i had done and plugged the lead back in, i got nothing. no reading at all.
i thought maybe it needed a few more turns around the lead so it could better pick up whatever it is that it picks up (i have no idea lol, the feedback from the electricity passing through it i assume). buuttt anywho, that didn't work either.
so im at a dead end again.
 

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What bike is that? (so I can look at the wiring diagram)

How many leads are coming from the gauge for the speedo?

How many leads are coming from the speed sender?

You might need to spray a shot of lubricant on the bicycle chain as well ;)
 
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Discussion Starter · #8 ·
Thanks for the bump CK

its a zx10b 1988. i have the diagram if you want (not sure if i can post it here, copyright and all?)
but basically the tachometer has three wires on the original dials. black and yellow (negative), Brown (+12v) and black (which feeds off the ignition coil).
the new dial only requires one cable for the revs, so i connected it to the black (ignition coil). which gave no result.

The new dials came with the speed sensor. so there are three wires from the speedo and three on the sensor. negative, +8v, and a signal wire.

Excuse my scribbles but here is the wiring for the new dials, may help.


And yes definitely needs a touch of lube hahaha (my sons project fyi)

Cheers fella
 

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Hmm...

First and foremost, these aftermarket gauges tend to be EXTREMELY finicky about their grounding so before you do anything else it is a good idea to run a dedicated ground wire all the way to the battery. Not to the nearest threaded hole in the frame, but the battery negative pole.


so you got a reading, until you fitted the plug lead back to the plug thus giving it a ground...

A pull-up resistor MIGHT work.



Upper is your current setup, black from coil connected to the blue/yellow from the gauge right?

Take the brown +12v wire from your original wiring, solder in a resistor of about 4,7kilo-ohms and connect that to the current setup. It should provide the gauge the power it needs to create a pulse. If that doesn`t work disconnect the black wire from the coil and do the lead wrap thing again. If that doesn`t work either try wrapping the wire the other way round the HT lead. If THAT doesn`t work, ask someone wiser than me...

Seems weird that they would have used a three wire hall-effect sensor and just use it to pick up a passing magnet. Do you have a picture of the speed sender? Since it came with the gauge it shouldn`t be a wiring issue...

Have you tested the sender itself. You might have to be a little creative with it but here`s essentially how to test a three wire speed sender and what to look for even if the sender itself is of a completely different design:

https://www.youtube.com/watch?annotation_id=annotation_685722&feature=iv&hd=1&src_vid=alR_toPdr4g&v=G1XzwZE6n8M

There, that should keep you occupied for a night or two, hope it helps.
 
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Discussion Starter · #10 ·
Thank you so much man. Some top tips there. And yeah will deffo keep me busy a while haha.

The gauge already has a direct connection to ground so should be all good there.

I see what you mean by the pull up resistor, I'm thinking that might do it. However before I jump straight in can I just make sure of a couple things (my electronics knowledge is basic lol). The brown is my +12v supply for the gauge, and the black is the negative side of the coil. So by connecting these with the resistor, am i likely to cause any other issues/damage something?

And no, I hadn't tested the sensor yet. Was next on my list but was unsure how to go about it, so thanks for link. I'm all clued up now.

Here's a pic of the sensor, it's pretty standard tbh.


Again, thanks for your help. Legend.
 

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Taking back a little since I can`t seem to find the wiring diagram to check if the brown wire is a constant hot or a switched 12v. Use one that goes through the ignition a.k.a. switched supply. Would need to see how the black wire connects to the coils but if it`s not a straight ground it shouldn`t cause a short. after all there is that resistor. But as always your results may vary so take my advice with a grain of salt. I do have basic electronics training but that was over a decade ago and never worked as such so I`m no tech support either, basically relaying stuff I`ve stumbled with myself and how I solved -or was told to solve- them.

Always a good idea to do a test connection with these:



before soldering stuff together permanently.
 

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Discussion Starter · #12 ·
The brown is indeed a switched 12v supply from the ignition.
And ignore me on the black wire. It's not negative at all. It feeds the coil for spark plug number 1. My bad.

I also have some electronics training, but like you it was over a decade ago. I just dabble here and there these days.
If you do want the wiring diagram (for future reference or whatever) I can send it to you.
 

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Look a lot like grom clocks. Same as cbr500 too, I think. Probably only the same skin deep though.
 

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Could there be a thinking error? Try swiping the magnet past the sensor back and forth really fast. I remember think my bicycle speedo wasn't working but I was just running the magnet too slow.
 

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Thank you so much man. Some top tips there. And yeah will deffo keep me busy a while haha.

The gauge already has a direct connection to ground so should be all good there.

I see what you mean by the pull up resistor, I'm thinking that might do it. However before I jump straight in can I just make sure of a couple things (my electronics knowledge is basic lol). The brown is my +12v supply for the gauge, and the black is the negative side of the coil. So by connecting these with the resistor, am i likely to cause any other issues/damage something?

And no, I hadn't tested the sensor yet. Was next on my list but was unsure how to go about it, so thanks for link. I'm all clued up now.

Here's a pic of the sensor, it's pretty standard tbh.


Again, thanks for your help. Legend.
I'll ask some dumb questions here.

Is that plug at the bottom left of the pic your magnet? If so, it actually looks like aluminum to me, rather than a magnet.

If it's actually just a magnet holder, maybe the magnet is on the holder backwards? Creating a reversed polarity issue. You know, north pole -south pole stuff.
 

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Was thinking the same but forgot to write, sure looks like loominum to me too. Good catch.
 

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Discussion Starter · #17 ·
Could there be a thinking error? Try swiping the magnet past the sensor back and forth really fast. I remember think my bicycle speedo wasn't working but I was just running the magnet too slow.
Yeah I have tried this, but I'm wondering if by doing this it didn't provide a regular enough pulse. I'm not sure.

I'll ask some dumb questions here.

Is that plug at the bottom left of the pic your magnet? If so, it actually looks like aluminum to me, rather than a magnet.

If it's actually just a magnet holder, maybe the magnet is on the holder backwards? Creating a reversed polarity issue. You know, north pole -south pole stuff.
Yeah it is a housing for the magnet. The magnet is visible on the other side. Theside where it is visible is the side that passes the sensor. I'm not sure on the poles tbh.
However it's definitely magnetic
 

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Discussion Starter · #18 ·
On a related note, I don't actually have anywhere to mount the magnet onto the wheel. And no holes anywhere on the disc/rotor.

I'm wondering, can I drill a hole in the disc to mount the magnet? Or will this affect its integrity or fail its mot?
 

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On a related note, I don't actually have anywhere to mount the magnet onto the wheel. And no holes anywhere on the disc/rotor.

I'm wondering, can I drill a hole in the disc to mount the magnet? Or will this affect its integrity or fail its mot?
Do your rotor bolts us an allen key? If so and the magnet is small enough you can put the magnet in one of them.
 
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