Has anyone ever taken a YPVS servo apart?

[Dave B]

I have a problem with a YPVS servo. When the ignition is turned on, it just runs backwards and forwards for ten degrees or so. It does not respond to the "Test PV" function on the Zeeltronic hand controller. Sometimes, it shows an "Error 1" warning on the controller- sometimes not.
I'm thinking that inside there is a motor, a train of gears and a potentiometer used as a poition sensor. I suspect an intermittent fault on the Pot.
Does the symptom sound familiar? And has anyone ever tried to replace the potentiometer?
Help and advice welcome.
Cheers
Dave

[alastairh]

I had one that was working fine and when re-fitted to the bike had decided to stop working. I brought a 2nd hand unit of flea bay. Motor resistance should be around 15 - 18 ohms (RHS Top and RHS bottom pins - unused pin is centre bottom - view on end of connector). Pot resistance should be 7.5k ohm +/-30% @ 20 deg C(top centre to bot LHS) Y/L to W/B. Top LHS to top Centre should be around 3.8k ohm and top LHS to Bot LHS about the same.

(Y-L to W/R) + (W/R+W/B) = 7.5k +/- 30%

From memory I don't think changing the pot was an option.

Power valves should open around 7,000 rpm if the control unit is working correctly. Check continuity of the wires / condition of the connectors.

[dusty350]

Hi
Pretty sure forum member "Bare" has posted about this before. Think he said Fzr1000 servo motor is the same ? Long time since I read about it so might be worth a pm to him.

Regards

Dusty

[kostas]

Correct Dusty,

Exup servo motors are the same.
I did open a servo once as I thought it was faulty. I think the test in the Haynes book is wrong.

The potentiometer can be replaced but I doubt you will find a replacement one as it is a carbon face type.
What I did is that I tools the cover off from the pot and cleaned the small wire type contacts that run on the carbon face. I also cleaned the carbon surface. Watch out the contact wires are very delicate.

My issue turned out to be the controller but the problem I had was not like the one you get. And since you have a Zeel fitted I doubt you have an issue with that.

Note you can open the pot side of the motor without messing with the gears. Just undo the screws from the side the wires go thru.

Cheers

Kostas

[Dave B]

Excellent, many thanks to all.
Now I have test data and a good idea how to go about the job.
I was thinking that at this stage I have nothing to lose by taking it apart- since it doesn't work anyway. I'll give it a fair chance to work before it goes in the bin.
If i can get it going, fine, if not it was scrap anyway!
Cheers and thanks again,
Dave

[dusty350]

Hi
I also read that servo's cycle differently when hooked up with a Zeeltronic system. Maybe worth researching that too.

Dusty

[bare]

As above Yama Exup servos are the ..SAME... part, albeit the connector plug differs in design.
Typically these sell for Very little on ebay (v low/no demand)
That said the rascals are tough, rarely failing except perhaps from Crash damage.
It's true though that the Servos' Potentiometer is a bespoke design and 'problematic' to replace ,
But then as an Exup servo is less coin than even a not quite right replacement pot..it's Pointless.

Note that the Yama controllers are common (too) failures
Zeel cycles identically to OEM.
BUT it's also user programmable to do whatever start up cycle dance ..pleases.