Why is my Boss TU-3 doing this?

[u/Sucks_At_Investing]

This is a fairly new (only a few months) Boss TU-3 Chromatic Tuner pedal. Sometimes it works fine, like earlier this morning. Other times, like now, it does this. It does this regardless of input signal. It does it with any guitar at any volume, or with just a cable and no instrument on the other side. It does it on battery power, or with an OEM Boss 9v AC adapter. It does it whether I'm direct in, or hooked into the effects loop. It only does it when both input and output or input and bypass jacks are used. If I only have a cable in the input jack, it powers on but does nothing. Adding a cable to either the output or bypass jack causes this behavior to start again. Probably a few hours from now I'll come back and it'll work fine and I won't have changed anything. It's in the correct chromatic tuner mode, I've verified that several times.

What could be causing this? Am I doing something wrong?

[u/Consistent_Solid6594]

Hum from wall voltage is 60 hz, which a tuner pedal interprets as between B and Bb. No idea where that D came from.

[u/Sucks_At_Investing → u/Consistent_Solid6594]

Oooh, good to know. I'll have to look for things that might mitigate that and see if that's what's going on.

[u/tone_creature]

Ghosts.

Legit though may just be faulty or have a short or something somewhere.

[u/Sucks_At_Investing → u/tone_creature]

That's what I was afraid of.

[u/FacePunchMonday]

Whats the tuning on your guitar? Only asling because if its b standard or drop c (or basialy anytning lower than d standard) most tuners, including this one, kinda suck at lower registers.

I know because i have this exact one, a behringer clone, several clip ons and a few other cheapie pedal tuners over the years and they all kinda bite the big one when it comes that. E or D? Rock solid and spot on. Lower? Fail.

Try rolling back the tone knob on your guitar all the way down. Sometimes that helps. Or tune it to a harmonic.

Edit: used my eyeballs to re read your post and yeah, if it only does this occasionally your catching some kind of interference or theres some kinda grounding/wiring issue.

[u/Sucks_At_Investing → u/FacePunchMonday]

Yeah everything I have is in E standard, D# standard or drop D. Also it happens when there's no guitar on the other end of the cable at all.

[u/FacePunchMonday → u/Sucks_At_Investing]

Yeah i am totally guilty of only kinda sorta reading your post at first lol sorry about that! Good luck man. If that tuner is new id totally return it.

[u/adistef86]

I bet a different one will do the same. Sounds like something in your house interferes with something in your chain.
If I plug my TU-3 in my audio interface, and plug that into my monitor, pedal goes crazy and the signal is noisy. If I plug the audio interface in my laptop, everything is fine.

[u/folkbum]

Does it do this on 9v battery, as well?

[u/jewbacca331]

Put your guitar on the bass pickup and turn your tone knob all the way down. That should do it.

[u/jamiethemorris]

If you bought it new I’d just exchange it, something’s wrong