Replacement controller for Wisper 705SE

Flying Dodo

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Jul 13, 2021
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Hi. I'm hoping someone can suggest a suitable replacement controller for a very old Wisper 705SE. It's stopped working and everything is dead. After getting the multi-meter out, whilst there's 36v going into the circuit board, there's no output voltage anywhere. Wisper Bikes say due to the age of the bike, they're not able to help as they don't have a replacement.

Is there anything available which might be a direct plug replacement or would it mean a complete new wiring loom, controller and display? And if so, where could they be bought from?

Many thanks.
 

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Nealh

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Direct replacement probably not, even a new Lishui model may need some wire soldering esp if connector are different.
A couple of options buy a LSW 675 from BMS battery but by the time you pay for P & P , one might as well buy a whole new electronics kit that will simply plug and play for about £75 - £100 for a nice KT option or the cheaper Brainpower on ebay.
 
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Nealh

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Nealh

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vfr400

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Jun 12, 2011
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To get the best advice re a replacement, you need to show all the connectors attached to your controller in a way that clearly shows what wires are in each connector. Also, you must show a picture of your control panel on the handlebars.

Before buying a new controller, it might be an idea to find out what's wrong with your bike. There are many possibilities other than the controller. I have no idea how you measured what's coming out of the controller, but I'm going to guess that you did it wrong becaause even if the controller blows up, there should still be something coming out of it. If nothing comes out of it, it means that nothing is going into it, so you need to find out how and why. Show us the control panel so that we can guide you how to check.
 
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Flying Dodo

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Jul 13, 2021
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I followed the main power cables and got 36v at the point they're soldered onto the circuit board, as stated above. I checked the +5v output and there's nothing. Nowhere else on the board has any power. Due to the age of the bike, the control panel only has buttons to increase/decrease the power level, but and as originally mentioned, everything is dead, so there's no voltage there at all either, but I knew that would be the case due to the lack of output from the circuit board.

If the board has a complete failure then there won't be any voltage coming out of it, which is the case here. It is a dead board - it has ceased to exist. It's not resting. ;)

I'll look at the useful suggestions mentioned above.
 

vfr400

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The power from those two wires doesn't go to power the 5v even when there's nothing wrong. If you just do as I'd say, you'd get to the cause of your problem quicker.
 

Flying Dodo

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There are only 2 wires from the battery and they just go to the circuit board.

even if the controller blows up, there should still be something coming out of it. If nothing comes out of it, it means that nothing is going into it, so you need to find out how and why. Show us the control panel so that we can guide you how to check.
Not the case, as 36v is going in, as already stated. The 5v feed come off further along the board - you can see it marked on one of the pictures.

As I've stated in my original post and in my follow up, there's no voltage anywhere else. Not on the rest of the circuit board, and not on the control panel on the handlebars. But attached are the photos.
 

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vfr400

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The controller is powered from the control panel, not directly from the battery. The wires that power the control panel branch off the two battery wires inside the controller, so if there is no power on those wires (red and black in its connector), a wire must be broken, but I bet you didn't check the voltage there.

The control panel is effectively an electronic switch. When you power it on, it switches power on the blue wire, which powers the controller with the same battery voltage.

Assuming that you have the voltage on the red and black wires, you can bypass the switch in the control panel to test your controller by bridging the red and blue wires. That will give normal throttle operation and level 1 pedal assist.

Control panels pack up when they get water in or when a wire gets ripped off the pub inside.
 

wheeliepete

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If you unplug the black 6 pin connector on the controller that runs up to handle bars, as VFR said, look for 36v on the black and red wires. If voltage is present reconnect then unplug display and look for same on waterproof plug coming out of multi connector. If you find 36v there, then the problem is with the display, poss. the power switch, if not then there is a break in loom from controller. In my experience with Wisper bikes, I have 3, fault in the display more likely than controller.
 

vfr400

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Open the control panel to test where the wires attach to the PCB if you have moulded connectors and the 4 into 1 harness. That's as long as you have one that screws together. The welded ones are impossible. For those, you'd have to cut into the harness to test, then repair the wires afterwards.
 

Flying Dodo

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Jul 13, 2021
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Thanks for your replies. The control panel is a sealed unit unfortunately but the first thing I did when starting this, was to check the connectors on the 9 pin plug going into the 4 into 1 connector which then goes into the control panel, as that was easier to check. That confirmed no voltage on any of the pins. I then removed all the rusty screws underneath the bike to then check the circuit board.

I've subsequently checked the continuity of each individual wire from the circuit board up to the control panel and that does indicate an issue with 2 wires shorting, so I'll try and bypass them to then see if that then gets the power on.
 

vfr400

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All you need to do is unsolder the problematic wires from the PCB, then solder a short across where the red and blue wires aaaaare soldered. Make sure you get the red that carries battery voltage and not one of the 5v reds. Obviously, the 5v reds only have 5v when the red and ble are bridged.
 

Tim@Wisper

Trade Member
May 6, 2021
11
3
Hello,
if you contact our support department support@wisperbikes.com we may have the controller you are looking for in stock so you can do a straight replacement.
 

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