Pendleton Somerby - how to fix broken cables at rear hub

[Nealh]

Drill the center out .

 

[saneagle]

Is there a good supplier of cables you would recommend?

I think they all come from the same place because they all have exactly the same wire in them, so whoever sells them the cheapest.

Sorry, didn't realize you were selling that. Managed to source one from a colleague, but will come back if that's not sufficient.

It wasn't mine. I just linked it because it was suitable and cheap. They're normally £7.

 

[AndiB]

Thanks to all for the help. I managed to replace the cable today. Write up below.
Sadly the bike still doesn't provide any assist. Any tips what to check next from anyone? (Will start a new thread for that... )

Cable change on Pendleton Somerby
Using a suitable tool (see eg @saneagle s post above) removed the cassette. Came off pretty easy, once I "cracked" the resistance on the thread. Unscrewed cassette the whole way.

The motor cover required a specialist torx bit, one with a hole in the middle. Luckily my company's workshop had some on hand.
Took off the plate and took out the motor from the hub.

Snipped all cables (3 large, 6 small) and pulled out the old broken cable.

To push the new cable in, I but an oversized length of heat shrink on the cable end, then pulled the shrink through first, pulling the cable behind. Overall that part was easy, just like @saneagle suggested.

Then solder all wires in, colour by colour, and cover each with heat shrink.

Put it all back together, done.

 

[saneagle]

Thanks to all for the help. I managed to replace the cable today. Write up below.
Sadly the bike still doesn't provide any assist. Any tips what to check next from anyone? (Will start a new thread for that...)

Cable change on Pendleton Somerby
Using a suitable tool (see eg @saneagle s post above) removed the cassette. Came off pretty easy, once I "cracked" the resistance on the thread. Unscrewed cassette the whole way.

The motor cover required a specialist torx bit, one with a hole in the middle. Luckily my company's workshop had some on hand.
Took off the plate and took out the motor from the hub.

Snipped all cables (3 large, 6 small) and pulled out the old broken cable.

To push the new cable in, I but an oversized length of heat shrink on the cable end, then pulled the shrink through first, pulling the cable behind. Overall that part was easy, just like @saneagle suggested.

Then solder all wires in, colour by colour, and cover each with heat shrink.

Put it all back together, done.

The problem is that the phase wires carry high voltage that's enough to do damage if one touches any of the thin wires. You need to check to see what's wrong. Don't give the motor any prolonged power when it doesn't move otherwise you can do more damage.

First check. Switch on everything and check whether you have 5v on the thin red and black wires. If there's no 5v, you've probably blown the 5v regulator.

Second check. Set your meter to 20v DC and measure the voltage between the black and each of the thin green, blue and yellow wires while you turn the motor BACKWARDS. You should see 5v pulsing on and off. If it doesn't pulse, you've blown a hall sensor.

Well done on what you've achieved so far. That's probably the most difficult repair that anybody can do to an ebike. It should be easy from here, just a bit of testing to find out what's wrong.

 

[Sturmey]

The motor coils in photo are very badly burnt. (see photos above)

 

[AndiB]

The motor coils in photo are very badly burnt. (see photos above)

Could that mean a broken motor? Wonder if I can do some sort of continuity check on the windings?

 

[AndiB]

The problem is that the phase wires carry high voltage that's enough to do damage if one touches any of the thin wires. You need to check to see what's wrong. Don't give the motor any prolonged power when it doesn't move otherwise you can do more damage.

First check. Switch on everything and check whether you have 5v on the thin red and black wires. If there's no 5v, you've probably blown the 5v regulator.

Second check. Set your meter to 20v DC and measure the voltage between the black and each of the thin green, blue and yellow wires while you turn the motor BACKWARDS. You should see 5v pulsing on and off. If it doesn't pulse, you've blown a hall sensor.

Well done on what you've achieved so far. That's probably the most difficult repair that anybody can do to an ebike. It should be easy from here, just a bit of testing to find out what's wrong.

Thanks @saneagle !
Will take the motor apart again this week and see if I can diagnose it like you suggest.

 

[AndiB]

Thanks to all for the help. I managed to replace the cable today. Write up below.
Sadly the bike still doesn't provide any assist. Any tips what to check next from anyone? (Will start a new thread for that... )

Cable change on Pendleton Somerby
Using a suitable tool (see eg @saneagle s post above) removed the cassette. Came off pretty easy, once I "cracked" the resistance on the thread. Unscrewed cassette the whole way.

The motor cover required a specialist torx bit, one with a hole in the middle. Luckily my company's workshop had some on hand.
Took off the plate and took out the motor from the hub.

Snipped all cables (3 large, 6 small) and pulled out the old broken cable.

To push the new cable in, I but an oversized length of heat shrink on the cable end, then pulled the shrink through first, pulling the cable behind. Overall that part was easy, just like @saneagle suggested.

Then solder all wires in, colour by colour, and cover each with heat shrink.

Put it all back together, done.

Started a new thread to collect your thoughts on further diagnosis https://www.pedelecs.co.uk/forum/threads/diagnose-pendleton-not-working.47383/
Already got some additional pointers from you all, thanks!

 

[Sturmey]

Could that mean a broken motor? Wonder if I can do some sort of continuity check on the windings?

I think you need a new motor. I would be inclined to buy a full replacement 36v 700c rear conversion kit for that bike and wire it in to existing battery.
(I reposted your photo so others may give an opinion)

 

[Nealh]

Yes motor windings are toast on one phase , even if you got it working applied power would be poor as that aprt of the winding will be demagnetised.

 

[saneagle]

I think you need a new motor. I would be inclined to buy a full replacement 36v 700c rear conversion kit for that bike and wire it in to existing battery.
(I reposted your photo so others may give an opinion)

View attachment 58409

I wouldn't give up on that motor. It got hot, but that's normal when you break a phase wire. It's probably still OK, but needs to be tested. There is now a higher probability that a MOSFET has blown in the controller.

To test the coils, you need a meter that can read very low resistances, as each phase is around 0.1 Ohms. You take three readings, one between each pair of phase wires, then between each phase wire to the casing to check for shorts.

When a motor can't turn because of any reason, the power still goes into it and becomes heat instead of motion. That's why you must never give prolonged power when the motor isn't turning smoothly. A very short burst is OK for testing.

 

[Ghost1951]

I wouldn't give up on that motor. It got hot, but that's normal when you break a phase wire. It's probably still OK, but needs to be tested. There is now a higher probability that a MOSFET has blown in the controller.

Would you not think that the insulating enamel on the wire of the burned coils will have broken down? I'd have expected them to be shorted out if not yet, pretty soon when some vibration gets at them.

I've seen some youtube videos of a Chinese girl rewinding and replacing field coils like that in old motors and generators. Amazing stuff really because even when they are burned up, most of the hardware is salvageable. There used to be an electrical engineering workshop in Newcastle that restored ruined alternators and starter motors for cars. I think they tackled anything and exchanged your ruined part for a re-built one. Mind - I am going back thirty years. They are probably just tossed away now and new parts bought from the main dealer at vast expense.

 

[saneagle]

Would you not think that the insulating enamel on the wire of the burned coils will have broken down? I'd have expected them to be shorted out if not yet, pretty soon when some vibration gets at them.

I've seen some youtube videos of a Chinese girl rewinding and replacing field coils like that in old motors and generators. Amazing stuff really because even when they are burned up, most of the hardware is salvageable. There used to be an electrical engineering workshop in Newcastle that restored ruined alternators and starter motors for cars. I think they tackled anything and exchanged your ruined part for a re-built one. Mind - I am going back thirty years. They are probably just tossed away now and new parts bought from the main dealer at vast expense.

It's probably OK. only testing will confirm.

 

[AndiB]

I think you need a new motor. I would be inclined to buy a full replacement 36v 700c rear conversion kit for that bike and wire it in to existing battery.
(I reposted your photo so others may give an opinion)

View attachment 58409

I'm still checking out all other components before taking the plunge to buy a new motor / conversion kit, but do you have any vendors you can recommend for a full kit, @Sturmey ? Doesn't hurt to start window shopping...
Thanks!

 

[saneagle]

I'm still checking out all other components before taking the plunge to buy a new motor / conversion kit, but do you have any vendors you can recommend for a full kit, @Sturmey ? Doesn't hurt to start window shopping...
Thanks!

Kirbebike kits have KT controllers. They do a 250w kit without battery, so you can keep your pendleton one if you want.