TromboneChat

Hi, all-

I’m having this problem on my 50A3 bell… the first valve (F valve) has started rattling/buzzing on a C when not engaged (middle C in 3rd position, 3rd partial C when played in 6th position or 2nd valve/2nd position…)

I’m guessing it may be the spring on the valve vibrating? I’m not sure. Anyone else with similar experiences? Any suggestions?

Thanks!

Are both valves and all linkages fully oiled?

Burgerbob wrote: Sun Feb 13, 2022 8:44 am Are both valves and all linkages fully oiled?

Plus all tuning slides lubed... Do the bottom caps fit firmly? If not, the rubber O ring might be on the way out, or not properly seated.

Thanks for the suggestions.

Yes, I keep them well oiled. I know what you mean, though—I’ve definitely picked up horns with completely dry valves that rattle.

The caps are tight. If anything, the tuning slides fit tighter than on most other horns I’ve had.

I adjusted my grip so that I could press on different parts of the valve while playing…the only thing that made the buzz go away was pressing on the end of the spindle, toward the cap, or taking off the cap and pressing the opposite direction on the valve core. Touching the free end of the spring sometimes made it worse, and sometimes had no effect.

I tried putting some slightly thicker oil (Superslick key & rotor oil) on the spindle and one drop down the slide receiver receiver onto the valve, but no effect.

Any other ideas? Can the spring possibly need to be wound tighter, like one more revolution around the spindle? I might try and see if that’s possible.

Maybe a full disassemble / clean / reassemble?
Something might not be seated correctly ?
Plus it's just fun to do!

Jimkinkella wrote: Sun Feb 13, 2022 2:43 pm Maybe a full disassemble / clean / reassemble?
Something might not be seated correctly ?
Plus it's just fun to do!

True—I may do this once I have time later this week!

Isn’t there a set screw that’s kind of hidden somewhere on the spindle? Is it tight?

ChadA wrote: Mon Feb 14, 2022 1:55 pm Isn’t there a set screw that’s kind of hidden somewhere on the spindle? Is it tight?

There's the set screw that fixes the cap onto the spindle, and there's also the threaded post that acts as the stop point for the bumpers on the underside of the cap.

https://www.youtube.com/watch?v=VqARW6TzANs might help - unless, knowing yourself, you know this ought to be a job for someone else. If you do take it apart, be careful how you handle the core because the brazed inner tubes are very thin and soft (and because any bending of the long thin spindle is going to be pretty fatal).

ChadA wrote: Mon Feb 14, 2022 1:55 pm Isn’t there a set screw that’s kind of hidden somewhere on the spindle? Is it tight?

Thanks. I believe it is, but I’ll double-check that later. Yes, it’s a small hex screw that allows you to take off/adjust the depth of the circle thing (technical term) that the linkage connects to.

Ok, the buzz seems to be gone!

I did disassemble and reassemble the F valve…and here’s what I realized:

If you are unaware of how the 50A3 is constructed, the minibal linkage for the F valve connects inside the spindle cap, while the linkage for the 2nd valve is connected to the outside of the cap. This makes for a pretty tight space for the F valve linkage between the cap and the valve casing. If the cap is absolutely all the way down on the spindle as far as it will go, all works as it should. If it isn’t, the geometry of that tight space is thrown off, and the linkage gets too close to the spindle cap. This is what was buzzing…in fact, I realized that if I held it a certain way, I would also hear a slight “click” when I released the trigger, as they momentarily intersected as the rubber bumper got slightly compressed on the return stroke.

I made sure to reassemble it with the cap pressed all the way onto the spindle tightly, and all seems to be well!

Thanks for all of the suggestions.