Boss TU-120 Electronic Tuner Schematic Roland LED Strobe Guitar Tuning
Wild_Bill
repaired, but have been unable to locate a schematic or service manual.
The output frequency at the Monitor jack, appears to be incorrect for the
internal Calibrate settings, and when checked with a reliable counter
(SC3100 AutoTracker readout) the freq is about 432Hz, when I think it should
be adjustable to over 440Hz.
I was about to ask Roland Support when I saw that they require registered
user identity sign-in/account to be established before asking a question.
I have the operating instructions, and it describes the pot adjustment for
the internal Calibrate steps, as something like "adjust the front panel Cal
(pot) until the drifting stops, and the LEDs appear to be stopped/remain
stationary".
The point of rotation where the front panel Cal pot gets the LEDs to stop
drifting is all the way to the end stop of the rotation, so I can't find the
mid position between scroll left/scroll right.. and the freq is about 432Hz,
not 440, when I assume that it should be able to adjust from below 440 to
over 440Hz as the Calibrate pot is adjusted.
The Calibrate output freq is independent of the 12-position Note Selector
switch.
I marked the 2 internal PC mount pots before twiddling them, but the freq
doesn't get to 440Hz.
After tweaking, I can see 129Hz For "C", not 130.81..(possibly just a
counter accuracy tolerance issue) but 242Hz for "B", not 246.9Hz.
I believe the tuning reference freq is from a 3-terminal component marked
Iwata 880.0 T (3 '79 Japan) with a tuning fork symbol on it.
I'm operating at a musically impaired level here, as I've only recently
become interested in learning to play guitar, and I don't fully comprehend a
lot of how actual frequencies relate to notes, other than the harmonics.
I have a functionig Boss TU-12 Chromatic tuner, so I don't really need the
older tuner, but I'd like to know if I can get it to work properly, since it
does have a strobing display that easier to see at a distance, moreso than
the-needs-to-be-positioned-closely TU-12's meter pointer.
I'd also like to lower the non-adjustable speaker volume too, perhaps later.
I don't think installing a 0-6 volume knob would be a solution.
--
Cheers,
WB
.............
N_Cook
news:Jp_bp.678852$Bh.1...@en-nntp-12.dc1.easynews.com...
Assuming the "880.0" is an oscillator is the wiring from the calibration pot
(definitely a resistive pot ?) directly to the 880.0 ? Is there a tuning
capacitor near the 880.0 ?
N_Cook
early 70s that hummed to themselves. Corrossion to the forks over decades
would lower the frequency
N_Cook
news:Jp_bp.678852$Bh.1...@en-nntp-12.dc1.easynews.com...
I would guess you have an 880Hz version of the 360Hz elements in these
watches
http://members.shaw.ca/abts/218_technical.htm
then corrossion over the decades slowing the frequency of the fork. There is
probably some range limiting resistors to the Cal pot. You could probably
get away with changing one/both of them a bit to change the capture range,
Meat Plow
If you need brushing up on the theory. Closest I have is a TU-15. If it's
layout is similar I could give you some freq readings for reference.
--
Live Fast, Die Young and Leave a Pretty Corpse
Wild_Bill
user control panel and selectors, and the basic instructions on the bottom
label.
http://www.bossarea.com/other/tu120.asp
If the tuner had had been able to adjust the Calibrate setup to 440Hz at the
Monitor output, I would've assumed that it was probably operating normally.
I suspect that the oscillator/tuning reference and/or other components have
drifted in value(s), especially since the thing is 30+ years old.
There are a few online manual sellers that list a service manual for the
TU-120 model, so I may end up going that route, or contact Roland support..
I just thought I'd check SER since several regulars are familiar with quite
a bit of musical gear.
The TU-60 model may be close, containing somewhat similar circuitry, and
about the same age, maybe Roland's first model.
http://www.bossarea.com/other/tu60.asp
The fairly current/more recent *TU-12* model is a completely different unit,
not surprisingly.. one SMT quad flat pack and a TV color burst 3.579..? MHz
crystal, but of course, numerous other components too (and I was able to
find an online schematic for the *TU-12* model).
I have this model, and it gets me tuned fairly accurately (using the
chromatic mode) according to a friend that's been playing a long time.
--
Cheers,
WB
.............
"Meat Plow" <mhy...@yahoo.com> wrote in message
news:pan.2011.03...@lmao.lol.lol...
William Sommerwerck
> a TV color burst 3.579...? MHz.
3.579545 MHz. That number should be burned into the brain of anyone (in the
US or Japan, plus some Central and South American countries) who services
electronic equipment.
Wild_Bill
mechanical tuning fork-type device would likely upset it's characteristics..
detune it.
I didn't think to feel the 880Hz component to see if it was actually
vibrating while I had it apart, but maybe it does.
The 3-terminal gizmo is maybe 8x12mm with maybe a 10mm height (metric, how's
that? heh). The thing is marked Iwata Japan, and a symbol (((Y))) except the
Y looks like a tuning fork.. I just assumed it was a ceramic resonator or
something similar.
If it hadn't been marked 880, I wouldn't have thought it had any direct
relation to the 440Hz that is supposed to be the Cal pitch/note? frequency.
The front panel pot (far right end of front) for the user to set during the
Cal setup is about as physically far from the 880 gizmo as it can get.
http://www.bossarea.com/other/tu120.asp
My days of drawing even partial schematics are essentially over.. I used to
do that stuff when I was driven by ambition and inspired by satisfying
curiousity.. but anymore, it just eats up countless hours, so I generally
avoid it.
I checked the values of a few items near the I/O jacks in case they'd been
subjected to a misplaced voltage source or similar mistake/external
equipment fault, but that was the extent of actual checking anything other
than reading the output freq.
I recall that the 880 gizmo was at one end (by the rotary selector) and the
right end appeared to be a combination of I/O jacks, audio circuit for the
speaker (faces up thru the top grille) and an area of ICs which seem tied to
the circuit that operates the strobing LEDs (which don't actually strobe,
but light in sequential groups of 2-3 which will appear to drift left or
right, but stop drifting when the note is accurate).
BTW, there is a front panel mic (beside the front pot) for picking up
various instrument sounds, or an electronic signal can be input into the
unit (electric guitar cable, etc).
I suspect that the 30+ year old components' values have drifted, and a
schematic or service manual would be the most practical approach for me.
As I mentioned, I have a tuner that works, but the older TU-120 appears as
though it would be handy to use.
--
Cheers,
WB
.............
"N_Cook" <div...@tcp.co.uk> wrote in message
news:ikq7eq$4g1$1...@news.eternal-september.org...
N_Cook
Even so-called Standard Kilograms gain something like 1 microgram per year
in very carefully controlled environments
Holding a guitar tuner to your ear is not normal practise
A Mr Iwata was publishing audio technical papers in the 1990s , the same
person ?
N_Cook
news:ikrv6k$ud3$1...@news.eternal-september.org...
I still remember 0.4971 and its significance
William Sommerwerck
Are you referring to the Peter Mitchell paper about the influence of the
pocket calculator on teaching math and science? I'd like to read the
article, but I'm blocked because I'm not a subscriber.
hrho...@att.net
> Wild_Bill <wb_wildb...@XSPAMyahoo.com> wrote in message
> then corrossion over the decades slowing the frequency of the fork. There is
> probably some range limiting resistors to the Cal pot. You could probably
>
> - Show quoted text -
Does the questionable unit have an 880 setting? Can you cross-
reference the good unit to the questionable unit at any frequency?
Wild_Bill
Instructions booklet shows 880 as an A note with the selector switch in the
High Octave setting.
It's helpful that you brought this up, and although I'd looked at the chart
previously and noted the selections covering frequencies of 130.81 to
996.76, I hadn't made the connection.
This appears to be another example of RTFM.
If you've ever heard the radio comedy routine where people call in to ask
Mr. Obvious for advice, it's a funny version (although it's all scripted,
not real).
Mr. Obvious, I think I have a wild animal under my sink.. (questions,
replies).. oh, and there's a switch by my sink that doesn't seem to have any
purpose, doesn't turn on any lights, (more).
I'd considered connecting the older unit to the newer tuner, but I haven't
since I wasn't sure about the output from the Monitor jack of the older unit
being an overload for the input of the newer tuner.
When I saw the freq readings, I was convinced that the older unit needed
repaired.
--
Cheers,
WB
.............
<hrho...@att.net> wrote in message
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