19 May
2005
19 May
'05
5:53 p.m.
Surely there's one encoder and IR transmitter for
the
entire keyboard (there may be several IR LEDs, but
normally they're wired in series and send the same
information). In which case if _any_ keys work, then
it's very unlikely the problem is with the IR transmitter.
Not true. IR formats where the energy density per bit type
differs can fail on specific codes due to the IR LED supply
capacitor failing. E.g. in the Sony SIRC protocol a 1 bit is
transmitted as 1.2ms of carrier and .6ms gap whereas a 0 bit
is .6ms of carrier and .6ms gap. In this case any command that
has a sequence of two or more 1s may fail where a code with
only single 1s way work.
Not very likely I'll admit but it can happen. The easy way to
diagnose this is if it works with brand new cells but cells a
couple of weeks old don't work well.
Lee.
.
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