Hello,
I had problems with the v-boost operation for some time. The movement did not happen at all or it happened incompletely. Then one day it stopped working. I first checked the servomotor by applying there voltage through b/r and b/y wires, but no action either way.
As I did not want to buy a new unit / motor, but on the other hand wanted well working adjustable system - had to think about getting it repaired or repairing it by myself. Then I remembered that my old Yamaha RD350LC (RZ350) does also have a servo motor in it's YPVS (Yamaha Power Valve System). This adjusts the exhaust port height in that two stroke motor. Considering the manufacturer's point of view - it makes no sense to produce small amounts of components like servo motors of different types - it felt likely that the motor and maybe the whole unit could be actually same. Now, the year model of RZ is -84 and the operation range (starting from 6000 rpm) is similar to that of v-boost. When checking it out, the colour codes of the wires were also identical. Only difference was the shape of the wire connector socket that has those five wires in. The connector socket containing three wires (brown, black and grey) was of the same shape. In RZ the grey was black/white colour code as far as I remember.
To check the operation of the v-boost control unit and possible similarity of the motor, I connected it to the YPVS servo via suitable self made wire adapters. The operation circuit seemed to be perfect, as the servo made correct open-close movement. Therefore the v-boost controller unit was proved to be ok and also the YPVS servo seemed to work. Well, easy solution would have been to just take the YPVS servo and connect it to V-Max, but then there would have been one not working unit. I measured the resistance values from the YPVS servo, and they were as follows:
9,5 ohm between black/red and black/yellow
6,46 kilo ohm between white/black and white/red
7,72 kilo ohm between white/black and yellow/blue
1,44 kilo ohm between white/red and yellow/blue
no continuity between the rest
For comparison the measurements from the not working v-boost servo were:
no continuity between black/red and black/yellow
4,61 kilo ohm between white/black and white/red
7,21 kilo ohm between white/black and yellow/blue
2,77 kilo ohm between white/red and yellow/blue
no continuity between the rest
Conclusion seemed obvious that the motor winding was broken somewhere.
Had to open the motor to see... The both motors (from v-boost and YPVS servo were of the same type, the text in the label is PXN-15EE13A, and below that is the manufacturing date mentioned).
To open the motor you have to dismantle the servo gearbox first from the other side of the package. Then two screws open from the gearbox side (under the pinions) that hold the electric motor in place, and the motor can be dismantled from the servo package. Then take the black rubber plug away from the motor top and carefully bend the two metal "ears" that hold the plastic head (where the b/r and b/y wires are connected by soldering) in it's place. After dismantling the wire head, the anchor (rotor) can be taken out - but not before the brass pinion has been removed from the end of the axle (this pinion gives the force to the servo gearbox). There is tight compression fitting between the brass pinion and the rotor axle, and violence must not be used as you have to put it back and fit it tight again. So after giving some direct flame heat by lighter directly to the pinion, it could be taken out easily.
The wire in the three pole anchor winding was broken from several places.
I first visited a professional motor service shop to ask for repair, but as predicted, the price would have been quite high for such a repair - allthough very possible to do. The guy sold be some suitable winding wire (diameter 0,12mm) as I wanted to try to repair it by myself. The wire only cost 5 euro.
The key point in this repair was to know how many rounds of wire was in the winding of each pole. How many rounds, not the wire length... And then the winding of each pole has to have same number of rounds. Calculated the number of rounds by carefully rolling the old wire away. There was exactly 250 rounds in one pole (meaning 750 rounds totally in the anchor).
The next thing to do was to solder (used 25 W solder) one end of the wire into the connection place of one of the poles. The connection is just below the commutator. Then started wrapping the wire around one pole counter clockwise and to calculate the rounds. After 250 completed rounds connected the wire by soldering it to the connection place of the next pole and repeated the action...250 rounds. And then once more again. Now the whole circle was done and the wire end had to be soldered into the same connector where it all began. After this confirmed the result by measuring the resistance in between all the poles. The result seemed ok (11 ohms).
By this arrangement the servo motor was resurrected. The repair took maybe two hours and cost 5 euros. I think it was worth it. The gearbox side of the servo motor was in perfect condition. Had to just put some new grease in.
And during the diagnosis it was also found that the servo motors and their units in the RZ series bikes are same as the v-boost. So these could be used for testing purposes as well as for the replacement parts, if there are no V-Max parts available. Only thing there to modify is the connector plug between the unit and the motor - unless you are going to replace both of them!
It also seems that the servo motor system of the Yamaha EXUP valve (used in FZR, R1 etc.) is same as the v-boost. This I can not yet confirm, because I have not had these here, but it is very likely from the manufacturer's point of view as said.
Someone who has access to EXUP servos, please check this.
I had problems with the v-boost operation for some time. The movement did not happen at all or it happened incompletely. Then one day it stopped working. I first checked the servomotor by applying there voltage through b/r and b/y wires, but no action either way.
As I did not want to buy a new unit / motor, but on the other hand wanted well working adjustable system - had to think about getting it repaired or repairing it by myself. Then I remembered that my old Yamaha RD350LC (RZ350) does also have a servo motor in it's YPVS (Yamaha Power Valve System). This adjusts the exhaust port height in that two stroke motor. Considering the manufacturer's point of view - it makes no sense to produce small amounts of components like servo motors of different types - it felt likely that the motor and maybe the whole unit could be actually same. Now, the year model of RZ is -84 and the operation range (starting from 6000 rpm) is similar to that of v-boost. When checking it out, the colour codes of the wires were also identical. Only difference was the shape of the wire connector socket that has those five wires in. The connector socket containing three wires (brown, black and grey) was of the same shape. In RZ the grey was black/white colour code as far as I remember.
To check the operation of the v-boost control unit and possible similarity of the motor, I connected it to the YPVS servo via suitable self made wire adapters. The operation circuit seemed to be perfect, as the servo made correct open-close movement. Therefore the v-boost controller unit was proved to be ok and also the YPVS servo seemed to work. Well, easy solution would have been to just take the YPVS servo and connect it to V-Max, but then there would have been one not working unit. I measured the resistance values from the YPVS servo, and they were as follows:
9,5 ohm between black/red and black/yellow
6,46 kilo ohm between white/black and white/red
7,72 kilo ohm between white/black and yellow/blue
1,44 kilo ohm between white/red and yellow/blue
no continuity between the rest
For comparison the measurements from the not working v-boost servo were:
no continuity between black/red and black/yellow
4,61 kilo ohm between white/black and white/red
7,21 kilo ohm between white/black and yellow/blue
2,77 kilo ohm between white/red and yellow/blue
no continuity between the rest
Conclusion seemed obvious that the motor winding was broken somewhere.
Had to open the motor to see... The both motors (from v-boost and YPVS servo were of the same type, the text in the label is PXN-15EE13A, and below that is the manufacturing date mentioned).
To open the motor you have to dismantle the servo gearbox first from the other side of the package. Then two screws open from the gearbox side (under the pinions) that hold the electric motor in place, and the motor can be dismantled from the servo package. Then take the black rubber plug away from the motor top and carefully bend the two metal "ears" that hold the plastic head (where the b/r and b/y wires are connected by soldering) in it's place. After dismantling the wire head, the anchor (rotor) can be taken out - but not before the brass pinion has been removed from the end of the axle (this pinion gives the force to the servo gearbox). There is tight compression fitting between the brass pinion and the rotor axle, and violence must not be used as you have to put it back and fit it tight again. So after giving some direct flame heat by lighter directly to the pinion, it could be taken out easily.
The wire in the three pole anchor winding was broken from several places.
I first visited a professional motor service shop to ask for repair, but as predicted, the price would have been quite high for such a repair - allthough very possible to do. The guy sold be some suitable winding wire (diameter 0,12mm) as I wanted to try to repair it by myself. The wire only cost 5 euro.
The key point in this repair was to know how many rounds of wire was in the winding of each pole. How many rounds, not the wire length... And then the winding of each pole has to have same number of rounds. Calculated the number of rounds by carefully rolling the old wire away. There was exactly 250 rounds in one pole (meaning 750 rounds totally in the anchor).
The next thing to do was to solder (used 25 W solder) one end of the wire into the connection place of one of the poles. The connection is just below the commutator. Then started wrapping the wire around one pole counter clockwise and to calculate the rounds. After 250 completed rounds connected the wire by soldering it to the connection place of the next pole and repeated the action...250 rounds. And then once more again. Now the whole circle was done and the wire end had to be soldered into the same connector where it all began. After this confirmed the result by measuring the resistance in between all the poles. The result seemed ok (11 ohms).
By this arrangement the servo motor was resurrected. The repair took maybe two hours and cost 5 euros. I think it was worth it. The gearbox side of the servo motor was in perfect condition. Had to just put some new grease in.
And during the diagnosis it was also found that the servo motors and their units in the RZ series bikes are same as the v-boost. So these could be used for testing purposes as well as for the replacement parts, if there are no V-Max parts available. Only thing there to modify is the connector plug between the unit and the motor - unless you are going to replace both of them!
It also seems that the servo motor system of the Yamaha EXUP valve (used in FZR, R1 etc.) is same as the v-boost. This I can not yet confirm, because I have not had these here, but it is very likely from the manufacturer's point of view as said.
Someone who has access to EXUP servos, please check this.
unk:
