New build, choked up?

[CraigB]

Hello, everyone!  I've got a strange problem with a new build and wondered if this has ever come up in your experience.  Just finished a single channel 2x6L6 AB763, with the tremolux trem circuit, all stock values.  I've built a few of these.  The trem works great with plenty of speed and depth range.  What's weird is if I turn the depth up say between 7-10, and increase the speed to a fairly fast clip, I'm getting a "mechanical" clicking sound coming from the choke (standard 125C1A Made in USA)in unison with the speed of the oscillation.  The noise doesn't come through the speaker at all.  If I lower the bias to about 10-11mA each tube, the clicking is not present at any setting of the trem controls.  Anything above that, and the choke no likey. I've tried different power tubes, PI and oscillator, same thing.  Anyway, just wondered, anybody ever had a choke do this?

[sluckey]

I haven't seen that. First thing I'd try is temporarily adding another filter cap to the node that supplies the screens and trem circuit.

[SILVERGUN]

Are you able to monitor current through the choke as it's happening?

[CraigB]

I haven't seen that. First thing I'd try is temporarily adding another filter cap to the node that supplies the screens and trem circuit.

Thanks Steve!  I will try that.  Would you suggest just tacking another 22uF/500v parallel with the existing 22uF/500 at that node?

Are you able to monitor current through the choke as it's happening?

Thanks SILVERGUN!  I haven't done that yet.

[PRR]

The choke current is varying. That should not be a problem. But "clicking" makes me wonder if the choke has loose windings or something. It might click for a lifetime or come un-done the first hard gig.

[CraigB]

The choke current is varying. That should not be a problem. But "clicking" makes me wonder if the choke has loose windings or something. It might click for a lifetime or come un-done the first hard gig.

PRR, that's what I was thinking it sounds like.  To me, the cost of ordering and installing a new one is worth avoiding the possibility of damaging any other components on the day that it stopped clicking 

[SILVERGUN]

Craig, my concern/curiosity was based on the idea that you might be hearing a brief over-current that is exposing that loose winding.
 
I would have to know before I put a new one in....just me and an over imagination, and a desire to know

[shooter]

I would have to know

Would an experiment like setting up a ?wobble micrometer? , (like measuring a rotor for tolerance), work, once you *adjusted* for normal *system vibration*? just a wild thought

[SILVERGUN]

I would have to know

Would an experiment like setting up a ?wobble micrometer? , (like measuring a rotor for tolerance), work, once you *adjusted* for normal *system vibration*? just a wild thought

I just wanted to see if he could see the 'click' on a Simpson's needle
 
I didn't want you to think that I was ignoring your post....it's a little (ok, a lot) 'out there'    beyond where I was heading

[shooter]

(ok, a lot) 'out there'   

I've always been 19degrees outta phase with the world , but we're in the same park, "looking for some visual indication of what our ears see"

[CraigB]

I would have to know

Would an experiment like setting up a ?wobble micrometer? , (like measuring a rotor for tolerance), work, once you *adjusted* for normal *system vibration*? just a wild thought

I just wanted to see if he could see the 'click' on a Simpson's needle
 
I didn't want you to think that I was ignoring your post....it's a little (ok, a lot) 'out there'    beyond where I was heading

Not ignoring your posts, either!  OK, I'll be honest....you guys are speaking about stuff that's clearly over my head 

[SILVERGUN]

Not ignoring your posts, either!  OK, I'll be honest....you guys are speaking about stuff that's clearly over my head 

No problem Craig.
I was suggesting that if you had an old analog meter (Simpson is a common type) with a needle indicator, that you might actually be able to see the current spike that is causing the click, by watching the needle jump in time with the click.
 
I don't have a "wobble micrometer" so shooter's experiment was out the window.
 

[CraigB]

Not ignoring your posts, either!  OK, I'll be honest....you guys are speaking about stuff that's clearly over my head 

No problem Craig.
I was suggesting that if you had an old analog meter (Simpson is a common type) with a needle indicator, that you might actually be able to see the current spike that is causing the click, by watching the needle jump in time with the click.
 
I don't have a "wobble micrometer" so shooter's experiment was out the window.

Ah, Simpson Needle, I get it.  I know I have a 15A panel ammeter somewhere, but...ordered new choke from Doug, so it'll be here faster than I can find the ammeter!

[jojokeo]

Hey there Craig! Aside from the good advice you're already getting I'm curious about the cap & resistor values all being the same (customary) & usual or not? Other than this you HAVE to provide us a sound demo? (love your playing) 

[CraigB]

Hey there Craig! Aside from the good advice you're already getting I'm curious about the cap & resistor values all being the same (customary) & usual or not? Other than this you HAVE to provide us a sound demo? (love your playing) 

Hey, glad to hear from you - yeah, I think I can whip up a demo once I get this issue straightened out.  Choke's on the way.  Let's hope that takes care of the problem

See attached, the only thing that the original power supply didn't have is the bleeder on the first cap 

[shooter]

You can borrow mine anytime, kinda beat-up, but works

[jojokeo]

See attached, the only thing that the original power supply didn't have is the bleeder on the first cap

I was actually thinking about the trem parts & area?

[Paul1453]

So Shooter,

That contraption of yours actually measures micrometer movements?

It is mechanical and has nothing to do with the magnetic field or current flow?

An interesting device and concept.

Can you tell us how you use this as a troubleshooting aid?

[pompeiisneaks]

He's joking, its a way to 'visualize' the phasing issues, which, doesn't really work :) 

Or at least that's how I took it lol

that evil grin at the end triggered a 'just kidding' kind of response from me

[Paul1453]

OK, so I guess I'm open minded enough to be considered gullible. 

I am willing to consider outside the box ideas, if they can be proven to work as an effective troubleshooting aid.   

[shooter]

while mostly humor, IF there is a loose, bobbin?, you should be able measure a physical movement even if you can't see it real-time, the mic measures .001" per increment.

[CraigB]

You can borrow mine anytime, kinda beat-up, but works

Sweet!

See attached, the only thing that the original power supply didn't have is the bleeder on the first cap

I was actually thinking about the trem parts & area?

Yeah, it's the same as 6G9 (I believe that's the model number) tremolux circuit.  See drawing

[CraigB]

These kinds of surgeries are usually a big drag, right?  But as luck would have it for me today, it was easy enough to push the board out of the way just enough to get my screwdriver on the mounting bolts and get the old choke out and replace.  Now, this is weird.  Holding it in my hand, give it a little shake and you can hear and feel the coil moving around inside the end bells.  I don't think that's normal, and the new one (same manufacturer) doesn't do that, either.

Anyway, problem solved, but I really hate throwing stuff away...so can anyone recommend how I might be able to stabilize the innards so I could reuse the thing on another build?  Maybe try dipping in varnish, let dry, dip again, etc?  Or should I just call it a bench paperweight?  Thanks for the replies, everyone, & hope ya'll have a great weekend!

[PRR]

> the coil moving around inside the end bells.

So take off the end bells and look what's up.

I recall a fair number of coils with wood/fiber wedges driven between core and bobbin. Maybe the wedge-whacker missed one.

[CraigB]

> the coil moving around inside the end bells.

So take off the end bells and look what's up.

I recall a fair number of coils with wood/fiber wedges driven between core and bobbin. Maybe the wedge-whacker missed one.

Thanks again PRR - opened it up, pulled off one endbell, no wedges.  The coil moves sloppily back and forth inside the lams.  I'm thinking a couple blobs of silicone between core and bobbin should do the trick, unless you think some hardwood wedges jammed in there would be a better plan.  Might even work to jam a couple little pieces of plain vector board on both sides?

[jojokeo]

Nice to have an irritating problem like that solved isn't it!? And even better that it wasn't too invasive on top of it    I find it really strange to have something like that which moves and even stranger that it was moving and causing the ticking sound and moving in sync with the tremolo!? But weirder things have happened in the amp world I guess? Now for that sound sample...???   

[HotBluePlates]

... opened it up, pulled off one endbell, no wedges.  The coil moves sloppily back and forth inside the lams.  I'm thinking a couple blobs of silicone between core and bobbin should do the trick, unless you think some hardwood wedges jammed in there would be a better plan. ...

I'd personally use wood to tighten it up. Then if you feel like silicone or varnish would be a good idea, you could do one of those.

[CraigB]

I find it really strange to have something like that which moves and even stranger that it was moving and causing the ticking sound and moving in sync with the tremolo!? But weirder things have happened in the amp world I guess? Now for that sound sample...???   

Yeah, weird.  Never had that before, and the spacing and orientation of trannys is the same as the other builds. Had a chance to play it for a while yesterday afternoon, really liking how it sounds and the trem works great.  Hopefully I'll have some time to get going on some tracks next weekend.  But for now, it's back to the day job     

I'd personally use wood to tighten it up. Then if you feel like silicone or varnish would be a good idea, you could do one of those.

Thanks HBP, a couple wood pieces pushed in did the trick.  I tried some pieces of circuit board cutoff, but the bobbin still slipped around.