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FZS600 Fazer / Re: Speed sensor fusing: power / current requirements
« on: 25 May 2022, 11:20:57 am »
Quick update for anyone in future looking for this issue on an fzs600 fazer speedo replace:
Summary: If you're replacing the speedo and keeping the original speed sensor it will probably work without this step, but I did it anyway.
- The speedo has this capacitor/zener diode combo between (a) the meter light input to the speedo (which is a secondary switched live) and (b) the speed sensor power output from the speedo.
- My previous diagram probably had the zener the wrong way round...
- I'm not clear what on it does. I'm pretty sure it doesn't reduce voltage. I guess it's either to (1) reduce "noise"/needle wobble on the speedo; and/or (2) to protect the sensitive speed sensor from voltage fluctuations.
- I expect that 25 years ago a talented yamaha engineer designed this feature into the circuit for a good reason anyway (let's hope he's now retired on company pension enjoying golf and warm saki...). I think these little details are behind the famous fazer reliability anyway, so how could I just bin it?!
- I couldn't confirm the specs for either the capacitor or the zener. So I bought an old wrecked speedo on eBay and cut them out and soldered (I'll add pics)
Side note on speedometers: The 1999 Fazer speedo is very different from the 2000 speedo. The circuit board is actually a completely different design with components in very different locations. I expect that they're probably 99% the same components wise. Future electronics tinkerers beware!
Summary: If you're replacing the speedo and keeping the original speed sensor it will probably work without this step, but I did it anyway.
- The speedo has this capacitor/zener diode combo between (a) the meter light input to the speedo (which is a secondary switched live) and (b) the speed sensor power output from the speedo.
- My previous diagram probably had the zener the wrong way round...
- I'm not clear what on it does. I'm pretty sure it doesn't reduce voltage. I guess it's either to (1) reduce "noise"/needle wobble on the speedo; and/or (2) to protect the sensitive speed sensor from voltage fluctuations.
- I expect that 25 years ago a talented yamaha engineer designed this feature into the circuit for a good reason anyway (let's hope he's now retired on company pension enjoying golf and warm saki...). I think these little details are behind the famous fazer reliability anyway, so how could I just bin it?!
- I couldn't confirm the specs for either the capacitor or the zener. So I bought an old wrecked speedo on eBay and cut them out and soldered (I'll add pics)
Side note on speedometers: The 1999 Fazer speedo is very different from the 2000 speedo. The circuit board is actually a completely different design with components in very different locations. I expect that they're probably 99% the same components wise. Future electronics tinkerers beware!