Wurli sustain pedal issue

[Alan Lenhoff]

After re-assembling my Wurli 200A recently, I'm getting a little, monentary static "tick" through the speakers when the sustain pedal is depressed nearly to the floor.   

I tried tightening all the grounds. Still there. I used my hand to actuate the sustain mechanism from underneath the top (without using the pedal) and did not hear the "tick."

Any ideas?

Alan

[pianotuner steveo]

Alan, it has been a while since I opened a wurli pedal, but I think there is a ground in the pedal base part itself...it may have broken or come loose.

[Alan Lenhoff]

Thanks for the tip Steve.  I'll check it out...

Alan

[Alan Lenhoff]

I opened the pedal, and found two "orphaned" ground lugs attached to a couple of screws.  I added a ground wire between those points, but I still hear the static tick through the speakers when I push the pedal down quickly.  (If I do it very slowly, I generally don't hear the tick.)

I'm thinking this has to be a ground issue somewhere. I loosened all the ground connection points, sprayed them with contact cleaner, and tightened them up well.  That didn't solve the issue.  I also used contact cleaner on the connection between the pedal cable and the piano.

I have noticed that with the top off, if I touch the sustain mechanism, the hum level of the unit falls somewhat.  (In general, the hum level of my Wurli is low.) 

Any ideas? I'm thinking of using a little emery cloth to polish up the ground points, but I just hate to potentially get any dust/debris in the Wurli that might short out some of the tines.

One other question:  When you attach the ground lugs to the screws that hold on the hum shield. should those lugs go outside -- or inside -- the shield?

Thanks,

Alan

[pianotuner steveo]

Is the outer pedal cable sheath grounded inside the pedal bottom?


Do you have a continuity tester or ohm meter?

[Alan Lenhoff]

Is the outer pedal cable sheath grounded inside the pedal bottom?

Do you have a continuity tester or ohm meter?

Actually, I think there is a slight gap between the bottom of the sheath and the top of the pedal. I'll have to take the pedal apart again and have a look.  I'm assuming there must be some sort of clamp-like device to hold the sheath inside the pedal -- and creates a proper ground connection.  Hadn't really thought of that.

And, yes, I do have a DMM that tests for continuity and resistance.

Thanks,

Alan

[Alan Lenhoff]

Just took it apart, and the housing is nicely clamped inside the pedal -- but it's broken just above the pedal.  No wonder there's not a good ground!

Time to do a little shopping for a new housing -- and the cable is a little frayed, too.

Thanks Steve.

Alan

[pianotuner steveo]

 No problem, my friend.

[Alan Lenhoff]

I ended up buying the Vintage Vibe cable kit.   Very easy installation.

I had considered buying housing and cable from a bike shop (cycling is one of my passions, so I know my way around bike shops), but doing that wouldn't have saved more than a few dollars (because you can't just buy the short pieces you need for the sustain pedal), and cutting cable housing is a pain. It's hard to do evenly and without collapsing the end you cut. So you wedge it open with a screwdriver, and then pull out your Dremel to grind it to make it even -- and then you melt the plastic that surrounds the housing. I'm sure experience -- and the right pro tools -- help, but it's no fun for me...

I tried the pedal briefly last night, and felt I still heard a little static tick when I used the pedal (although less often and lower in volume than before).  So, I'll have to check out the piano's grounds. At least, though, I now have a pedal that I can actually ground.

Kind of excited because after recently replacing one speaker in my 200A, and putting some stick-on foam insulation  tape on the inside of the cover to provide damping, I can finally run the piano at pretty much maximum volume without any buzzing or feedback. I didn't know that was possible. It really sounds good.

Alan

[Alan Lenhoff]

I still haven't solved this issue. I tried leading an extra ground wire to the sustain rod bracket, but that didn't do it.

One curious thing:

On the rod that activates the sustain mech, there is a large spring with a sort of cap-like fitting on the top and the bottom.  Looking at the bottom of the spring, I can see that there is a rubber grommet -- maybe an inch in diameter --  that is sticking out considerably from below that bottom cap. It seems to be wedged between the cap and the bottom of the cabinet.

I have no idea whether that grommet is supposed to be neatly seated underneath the bottom cap -- or whether it doesn't belong there at all.  I'm mostly wondering whether it's either preventing that bottom cap from making a necessary ground contact -- or whether the grommet is supposed to be keeping that spring assembly from making contact with what's below it.

Any experience to share?

Alan

[pianotuner steveo]

Good question. I think the rubber washer is there to prevent metal on metal noise, but the cable ferrule ( is that the right word?) shoud be connecting to ground through the threads....

[Alan Lenhoff]

Good question. I think the rubber washer is there to prevent metal on metal noise, but the cable ferrule ( is that the right word?) shoud be connecting to ground through the threads....

That certainly makes sense.

Just to clarify the issue, I don't hear static sounds when the pedal is fully depressed and held down.  I only hear a single static pop through the speakers just when the pedal begins to travel down -- when I've depressed it a 1/4" or so.

Makes me wonder whether something in the sustain mechanism (in the piano, not the pedal) might be contacting a ground wire -- or an ungrounded part -- when it starts to travel upwards.

I'll have to find some time this weekend to explore this more. 

[adcurtin]

take your multimeter and set it to continuity mode (it should beep audibly when the 2 probes are touching). Connect 1 probe to chassis ground, and the other to pedal ground, then depress the pedal. If the meter doesn't beep the whole time, it's a ground issue. If it continuously beeps, then it's something else.

[Alan Lenhoff]

Thanks for the suggestion.  Will try...

[Alan Lenhoff]

take your multimeter and set it to continuity mode (it should beep audibly when the 2 probes are touching). Connect 1 probe to chassis ground, and the other to pedal ground, then depress the pedal. If the meter doesn't beep the whole time, it's a ground issue. If it continuously beeps, then it's something else.

I think you're on to something here:  At the point in the travel of the pedal where I hear that static sound, I do lose continuity to ground.  Continuity returns as soon as I depress the pedal a touch further.  That failure point coincides with the point at which the dampers just start to lift off the reeds.

(If I slightly unscrew the ferrule connecting the pedal cable to the piano, the cable becomes more slack, and the failure point occurs when the pedal is depressed closer to the ground.  But it's still at the point where the dampers first lift off the reeds.)

I checked the continuity to ground at the ferrule. Same Issue. Checked the damper connecting rod inside the piano. Same issue. Checked the damper rail lift arm (that the damper rod connects to) and it DID NOT have the interruption of the continuity.

Any thoughts/suggestions?

Alan

[pianotuner steveo]

I would try running a ground wire from the connecting rod to the lift arm....

[Alan Lenhoff]

Sounds logical.  First thing, though, is that I can't see a place to attach a ground to the connecting rod.  Maybe I'm wrong, but it seems like the only way that rod is grounded is through the threads of the screw that attach it to the damper arm lift rail.  Sure doesn't seem like it would be a reliable ground.  Am I missing another connection to ground for that assembly?

Then, I noticed that if I press a finger on the lift rail while I operate the pedal, the static click goes away.  There's already a ground wire leading to the rail, but I added a second one from a screw on the amp base plate.  Didn't solve the issue, but, again, I can make the problem vanish by holding my finger on the lift rail.

I know the solution must be simple -- but it's frustrating... 

Alan

[pianotuner steveo]

What about scratching or sanding a spot all the way around the connecting rod, wrapping a wire around this spot and soldering the wire? Then run the wire up to the lift arm and connect it to a screw. ( I believe there is at least one screw on this rod) If  this doesn't help, it may have to do with the spring possibly breaking the ground connecion temporalily when the edal is depressed.... Actually you may want to check this first with the continuity tester....if so connect the wire to the spring too.

[Alan Lenhoff]

Good ideas.

I started experimenting with a wire and some alligator clips.  I found that I could lose the click if I put one clip on the lift rail and one on the connecting rod.  But it only worked if I pushed on the clip that was on the rod.

The clip handles are insulated, so I wasn't providing more grounding with my finger.  But I came away unsure whether pressing with my finger was helping to get better contact on the ground -- or whether pushing on the mechanism was simply causing something to make better mechanical contact. That ought to be easy enough to test -- but that's all the time I have today.

I'm thinking that if I do have to connect a ground wire to the rod, maybe soldering, plus using a hose clamp would make it secure.

Anyway, to be continued....

Thanks Steve.

Alan

[pianotuner steveo]

 I think the pressure helped to make better contact.

The clamp is a good idea.

This info will be helpful to all once we figure it out!

[adcurtin]

making a good solder connection to the connecting rod (I assume it's pretty much the same as the piano you sold me) is going to be difficult, especially with it inside the piano. To make a good solder connection, you've got to get the connection rod hot enough to melt the solder (though just the part your want to melt the solder to, not the whole thing). The easiest way to do this is with a small blowtorch, heat the part of the rod on the opposite side of the rod from the solder point, so the solder won't be directly in the flame (rosin burns). You also definitely want to sand the part of the rod you intend to solder to, to remove oxidization and ensure a proper connection. If you're careful (and / or have proper shielding, they make some stuff for when soldering together plumbing pipes that is for heat insulation from the surroundings) you could try soldering that in the piano.

[Alan Lenhoff]

Adcurtin, I'm sure you're right that to get a proper solder joint, you have to heat that rod far more than you could with a soldering iron.  But any sentence I write that begins "I used a blow torch..." probably ends with "and when the fire fighters arrived at my house..."  This is beyond my comfort zone.

Seems to me that since every other ground connection in the piano is a physical one (rather than a soldered connection), that I ought to be able to do that with the rod, too.  A couple possibilities:

1)  Use a hose clamp to attach a ground wire in place. Maybe I'd even line the clamp with a piece of rubber cut from a bike tire inner tube to give it some grip so it doesn't slip.

2) There are a variety of copper grounding clamps available that are apparently used to attach ground wires to water pipes.

So, I'll be experimenting along these lines.  (See example photos below.) In either case, I'd make sure to sand the rod first.

Any suggestions on how to maximize the quality of the ground?  Would a relatively thick gauged wire work better than a thin one?  The part does move, so would using stranded wire be advisable?  Or would that compromise the quality of the ground?

Thanks,

Alan

[adcurtin]

I would try to use similar gauge stranded wire (I think it's 14 or 16 they used for the other ground wires).

If you use a method other than soldering, make sure to test the resistance of the connection to make sure it's a good connection. The blowtorch I would use it a radioshack soldering iron with a torch tip, think like a creme brûlée torch, but a little smaller. (this guy: http://www.radioshack.com/product/index.jsp?productId=2062753 ; it comes with the blowtorch tip as well.)

something else you could try is sanding the point of contact beween the top of the rod and the damper rail, and a wire brush on the screw, including the threads. That's metal on metal, so I would think it should be able to provide a ground connection. You can test the resistance before and after to see if it improves.

[Alan Lenhoff]

Thanks very much.  With your suggestions, I feel like I have a pretty good menu of solutions to try over the next several days.

One more question:  I just want to make sure that my lift arm and rod are connected with all the pieces in the right place.  From outside to inside, I see:

The bolt head, a wave washer, the lift arm, a felt washer and the rod. So, in other words, the bolt threads are the only thing that connects the grounded lift arm to the "needs-to-be grounded" sustain rod.

[Alan Lenhoff]

My problem is solved.  Finally!

There's a clue to the solution earlier in this thread. I mentioned that when I pushed on the temporary ground wire connection I had added to the damper connecting rod, it caused the static tick to vanish.  Steve said the pressure was probably helping to make better contact.  That proved correct -- but it apparently wasn't better contact for the ground wire that was making the difference.

I discovered that I could actually make the sound vanish by pushing lightly anywhere on the damper connecting rod or the damper arm lift rail.  (And it wasn't that I was grounding those parts with my finger -- I could get the same effect pushing with the handle of  a screwdriver. )  Something was making poor contact.  But what?

I finally pulled out a can of Caig Deoxit contact cleaner, and used a little on the metal pins on which the damper arm lift rail rotates, and at the top and the bottom of the spring assembly attached to the rod. 

It is perfectly silent now!  (I think the issue was those pins.) 

One other take-away:  We had discussed how to add a ground wire to the damper connecting rod.  My no-solder method actually worked well.  (Lightly sanding the connection point, and using a small hose clamp to secure the wire to the rod.  I used a crimp-on spade connector on the end of the ground wire to give it a larger surface area for the clamp to grip.)  Maybe this info will come in handy for someone else.

Anyway, thank you Adcurtin and Steveo for your insights and suggestions. I'm so happy to have solved this annoying issue...

Alan

[pianotuner steveo]

YAY!

[icelander]

...

I finally pulled out a can of Caig Deoxit contact cleaner, and used a little on the metal pins on which the damper arm lift rail rotates, and at the top and the bottom of the spring assembly attached to the rod. 

It is perfectly silent now!  (I think the issue was those pins.) 

...

Sorry to bump this old topic but I found this thread from a google search. I've got a 200A and have been experiencing a very similar static tick when using the sustain pedal. Mine seems to occur on pedal release, and it only happens randomly, not every time (maybe once every 5-10 pedal releases or so). I've eliminated the pedal as the culprit since the same thing happens when using either the original pedal or a brand new Vintage Vibe sustain pedal.

Alan, if you're still around, could you possibly clarify which "metal pins" on the damper rail lift arm you are talking about in the quote above? Do you mean the ends of the metal rods that run through the center length of each rail (both bass and treble sides). See the attached photo where the red arrow is pointing. Or do you mean some other metal pins inside the damper rod lift arm bracket?

Just looking for which ones so I can try some contact cleaner on the same spots and see if my issue also goes away.

Thanks.

[Alan Lenhoff]

...

I finally pulled out a can of Caig Deoxit contact cleaner, and used a little on the metal pins on which the damper arm lift rail rotates, and at the top and the bottom of the spring assembly attached to the rod. 

It is perfectly silent now!  (I think the issue was those pins.) 

...

Sorry to bump this old topic but I found this thread from a google search. I've got a 200A and have been experiencing a very similar static tick when using the sustain pedal. Mine seems to occur on pedal release, and it only happens randomly, not every time (maybe once every 5-10 pedal releases or so). I've eliminated the pedal as the culprit since the same thing happens when using either the original pedal or a brand new Vintage Vibe sustain pedal.

Alan, if you're still around, could you possibly clarify which "metal pins" on the damper rail lift arm you are talking about in the quote above? Do you mean the ends of the metal rods that run through the center length of each rail (both bass and treble sides). See the attached photo where the red arrow is pointing. Or do you mean some other metal pins inside the damper rod lift arm bracket?

Just looking for which ones so I can try some contact cleaner on the same spots and see if my issue also goes away.

Thanks.

First of all, you get points for searching the archives to find this old thread, rather than asking the question over again.  (The archives of this group are nothing short of amazing for solving issues.)

Unfortunately, I no longer own a 200A, so I can't take a look to refresh my memory.  (I've become a Wurli 140B guy.) But as I recall, yes, it would be the rods you mentioned, and the cleaning was done at the points where the damper lift arm rotates on those rods as it moves up and down.  I also used a little contact cleaner on the top and bottom of the spring that attaches to that arm.  I can't say which cleaning point got the job done.

In hindsight, I would probably not use a contact cleaner spray in the insides of an electric piano, which might get it into places where it doesn't belong. So, I'd use a brush with some contact cleaner or maybe some 99% isopropyl alcohol at those points.

I hope my memory about the above is correct. Let us know if you're successful.

Alan

[cinnanon]

Do you have a grounding wire that connects the damper mechanism to the reedbar? It snakes through the middle.

[jam88]

Alan, totally off topic-- Thanks, belatedly, for all your great work with the Michigan Daily. It was an interesting time to be in Ann Arbor. Great music!

(From Bob, retired in Traverse City)