Arfa Daily wrote in message
...


"N_Cook" wrote in message
...
I don't remember seeing this since the days of wired-in VCR remotes. A
chain
of R varying from 680R to 10K for 11 of the main key switch sensing, not
diode array. That single resistance-set control line goes through the 14
pin
lift-off front panel connection to the main micro. Was thinking if
outside
the allowed range, or dirty contacts, then perhaps an illegal mode, but
they
check out true considering E12 series. High probability of a break
somewhere
in such a chain of SM resistors.



I have seen this scheme of button sensing on many audio units,
particularly
of Sony manufacture. Makes for very simple software to determine which
button has been pressed. The CPU only needs to read a single A-D input
pin,
and then compare the result to a lookup table programmed with what
function
belongs to what sensed voltage.

Arfa


Made a return with effects selection, with a standatd pot, on likes of
Roland Cubes.

One other person out there had this symptom ( unanswered)
"Im trying to fix an old car stereo, Sony XR-410. Cassette player works fine
but there is no sound in FM mode altough the frequency is displayed."
but as not a commonly reported fault I have to continue with front panel
fault cue