Hi Folks, I am moving this query here from my original (mistaken) posting in FAQ’s section ‘threepenny bit motor’ problem on a Thompson 36v SLA bike.
The bike has a rear hub 200 watt, 8 wire hall motor, as well as knocking/bumping under power, it knocks even when switched off, once pedalled up to about 6mph, (with the bike on it’s stand) Putting a meter across the main power cables show the motor acting like a generator, 12v and more being read. (an earlier thread had sug. Making some logical meter tests).
On the tiny ‘green’ hall sensor lead to -(black lead) the knock starts when 6v is ‘generated’. (however, on the blue and yellow hall wires to - only 3v was generated). Disconecting both these Yel/Blu wires completely, stopped the knocking, but still registered 6v generated on the green wire.
Finally, reading between the black- and red supply (whilst pedalling) gave 6v, obove that voltage the knocking cuts in.
Doing the ‘turn the wheel backwards’ to check the hall sensors (as recommended in the earlier thread) showed a regular series of 3 pulses at 6v followed by 3 at 0 volt. This was for yellow and blue hall wires, but nothing showing on green wire.
So I removed the rear wheel and with utmost difficulty, due to the magnetism! (had a real battle to remove the rotor, only with the spindle gripped in a 6" bench vice and an enormous pull was I able to withdraw rotor from the wheel rim magnets).
No evidence of any catching, so as suspected it’s an ‘electrical’ knock. All the tiny hall wires checked ok for continuity within the hollow spindle.
But,testing each hall sensor on the rotor in turn showed yellow to – (neutral) 3.4ohms; blue to – also 3.4 ohms but green to – ...nothing (open circuit)……..a duff hall sensor?
It is marked S41; 421.
I have been on to technical help at Farnell and the Hall they sell for £2.48 an OHN 314OU, it is 4.5 mm wide, (mine is 3.5mm) and my ref. S41;421 means nothing to Farnell.
So, unless I use my Dremel mini grinder to open up the slot in the rotor... I am stuck! (but hope this 'open heart surgery' is not req.)
Be very grateful if any electronic experts can rec. a suitable suplier of a 3.5mm Hall sensor. I may have been able to post some pics here, if they do not appear...sorry! silversurfer
The bike has a rear hub 200 watt, 8 wire hall motor, as well as knocking/bumping under power, it knocks even when switched off, once pedalled up to about 6mph, (with the bike on it’s stand) Putting a meter across the main power cables show the motor acting like a generator, 12v and more being read. (an earlier thread had sug. Making some logical meter tests).
On the tiny ‘green’ hall sensor lead to -(black lead) the knock starts when 6v is ‘generated’. (however, on the blue and yellow hall wires to - only 3v was generated). Disconecting both these Yel/Blu wires completely, stopped the knocking, but still registered 6v generated on the green wire.
Finally, reading between the black- and red supply (whilst pedalling) gave 6v, obove that voltage the knocking cuts in.
Doing the ‘turn the wheel backwards’ to check the hall sensors (as recommended in the earlier thread) showed a regular series of 3 pulses at 6v followed by 3 at 0 volt. This was for yellow and blue hall wires, but nothing showing on green wire.
So I removed the rear wheel and with utmost difficulty, due to the magnetism! (had a real battle to remove the rotor, only with the spindle gripped in a 6" bench vice and an enormous pull was I able to withdraw rotor from the wheel rim magnets).
No evidence of any catching, so as suspected it’s an ‘electrical’ knock. All the tiny hall wires checked ok for continuity within the hollow spindle.
But,testing each hall sensor on the rotor in turn showed yellow to – (neutral) 3.4ohms; blue to – also 3.4 ohms but green to – ...nothing (open circuit)……..a duff hall sensor?
It is marked S41; 421.
I have been on to technical help at Farnell and the Hall they sell for £2.48 an OHN 314OU, it is 4.5 mm wide, (mine is 3.5mm) and my ref. S41;421 means nothing to Farnell.
So, unless I use my Dremel mini grinder to open up the slot in the rotor... I am stuck! (but hope this 'open heart surgery' is not req.)
Be very grateful if any electronic experts can rec. a suitable suplier of a 3.5mm Hall sensor. I may have been able to post some pics here, if they do not appear...sorry! silversurfer
