790 Display Problem

[blooka]

Hi all
I have just replaced the display on my wife's bike cyclamatic CX2
I must have ordered the wrong one as when it arrived it had a different connector
Mine is 1 black connector with 6 wires in it, the display that arrived had 3 separate connectors each with 2 wires to it.
I thought no problem ill just resolder the wires as they are all the same colour. Unfortunately this didnt fully work
It powered on ok and seemed to show battery use ok but when i put it to mode low nothing happened and then when i put it in
mode med and high it started working ok but without the need to turn the pedals . I nearly shot out of the garage lol
Also the headlight didn't turn on or off. Anyone know the correct wiring for this hopefully i haven't blown anything.
i have posted some pics if this helps
many thanks
Dave

 

[Benjahmin]

Generally displays and controllers are bought as a matched pair, otherwise problems, such as you are having, ensue.

 

[saneagle]

There are two types of 790.One is digital and the other is analogue. The only way to know is by measuring the voltage on the green wire. The analogue one is 1v on level 1, 2v level2, etc. You can't measure any voltage on the digital one., but if you look inside it, two of the wires will me marked tx and rx on the PCB where they connect.

You should be able to make your bike work temporarily without any control panel. Just put a switch or bridge between the red and blue wires. If it doesn't work, you might need to bridge the green and another wire that isn't red, black or blue. Tell me what colours you have and I should be able to tell you.

 

[blooka]

thanks for the reply
not sure which wires i need to look at
there is a picture of the wires coming out of the controller do i just put a bridge across 2 of those
got no voltage from green wire when running on new display
its weird the bike wheel runs speed med. and then high ok but nothing on low.
but it does this when i do not turn the pedal. Also why is the light not working?
the bike is 2016 so i presume it an analogue display but not sure
if i cant fix it by rearranging the wires ill just buy another one that fits but cant seem to see any with my connector
thanks again for the help its much appreciated
dave

 

[saneagle]

Instead of sending data to your controller to tell it what power level to give, you're sending it a throttle signal down that green wire, which is zero throttle on level 1 (1v), low throttle on level 2 (2v), half throttle on level 3 (3v), and if you try the walk assist, it'll go full throttle (4v).

 

[blooka]

thanks for the reply
ill probably just buy a new speed controller and display all together.
as the other ones are old
would something like this be ok?
36V 250W/350W E-bike Scooter Brushless Speed Motor Controller with LCD Panel UK | eBay
many thanks again for the advice
cheers dave

 

[saneagle]

All controllers work the same, so it'll work, but it probably won't be plug-and-play.

First, check the size against your present one to make sure that it fits in the compartment. It gives a maximum of 13 amps, which is a bit on the low side, though should be OK for a 20" wheeled bike. Check what's written on your present one, then decide if you would be happy with more, less or the same power

You will probably find that the pedal sensor works backwards with it, so you have to take the chainwheel and magnet disc off and flip the magnet disc over.