Calibrating a Boss TU-12H

Stephen Gambrell · Post by **Stephen Gambrell** » 6 Jul 2003 3:55 pm

Am I imagining things(again), or was ther a thread on calibrating a Boss TU-12H tuner a while back? I think mine's off a little, and I want to start using it again. Can anybody help? THANKS!!

Loren Morehouse · Post by **Loren Morehouse** » 6 Jul 2003 7:21 pm

Stephan, I too have one and there's no adjustment for calibration, only pitch. Loren.

Doug Earnest · Post by **Doug Earnest** » 7 Jul 2003 5:09 am

There was a thread about two years ago on this subject.

You can calibrate the TU12H, you have to take it apart and find the little pot. It's one of those little round white do-hickeys with the straight slot in it. I don't know that it is advisable, but it isn't hard to do.

We are getting ready to move so my wife packed up my music room stuff while I was out of town. Haven't seen my TU12H since.........

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Doug Earnest
The only Zum Keyless U12, Fender Cyber Twin

Bill Crook · Post by **Bill Crook** » 7 Jul 2003 10:42 am

Better let a "Teckie" type guy do it for you. He will have the necessary equipment to do it right. Without the Signal generators and scopes,etc,etc, you WILL cause more problems than you fix.

"Been there, Done that,Got war stories about it"

Stephen Gambrell · Post by **Stephen Gambrell** » 7 Jul 2003 4:43 pm

I've got a scope, signal generator--all that stuff. Just, when I popped the back off the tuner, I didn't see a little pot! All I want to do is make the Boss match my other tuners, which all match each other.
Did I just say that????

Bill Crook · Post by **Bill Crook** » 8 Jul 2003 3:56 am

Stephen......

There should be 3 trimmer adjustments in the tuner.

1) One is for the Mic volumne input when used with acoustical guitars. It adjust the input level to the tuner.
2) One is for the frequency osc,(Tone Generator). This sets the tone heard when the note is produced by the tuner. Also,is used as the pitch reference point when used to check tuning.
3) One is for the meter movement. This trimmer is used to adjust the needle pointer to "0" when the frequency osc is KNOWN to be at the correct pitch.

As the battery begins to get weak, the tuner WILL begin to show wrong values. A weak battery cause the tuner to creep upward a bit. Also,keep in mind that even room tempature can affect the tuner's main osc function. Just the nature of any osc driven device.

Be sure to let Freq counter,O-scope,DVM,Tuner,etc,etc all be turnd on for at least 20 minutes to stabilize. You will be chaseing your-self if you start tweakin' things early.

Bill

Doug Earnest · Post by **Doug Earnest** » 8 Jul 2003 6:15 am

Stephen,
You have to take the boards out of the tuner to get to the trim pots as well as I remember (as I said, I can't find mine).
Bill, I'm sure you know more about this than I do, but does this thing really have a tone generator? It isn't the kind of tuner that produces an audible tone, it only recognizes one. Or does it have an internal generator to use as a means of comparing the sound being tuned to a reference? Obviously I don't really know how a tuner works, just curious?
Good luck Stephen.

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Doug Earnest
The only Zum Keyless U12, Fender Cyber Twin

Bill Crook · Post by **Bill Crook** » 9 Jul 2003 4:48 am

Some do,Some don't............

Most of the small ones made today don't. These $39-$59.00 units are considered to be throw-a-way devices. The early models mostly always had sound output (The AT-12,for example) built-in the system. These tuners generally sold for a bit more coins than the cheaper overseas stuff.

Anyway,all of em' have calibration trimmers in them. Again,I suggest that we really don't go into them without a somewhat working knowledge & proper equipment.

Stephen Gambrell · Post by **Stephen Gambrell** » 9 Jul 2003 11:15 am

Thanks, guys. I think I've got it corrected, and I couldn't have done it without help! I love the "Electronics" section---nobody gets mad!
Close this one up, please.