The TU-120 model (old one with strobing LEDs) has a fairly straightforward
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" wrote in message
news

http://guitartunerguide.com/

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