Bob F wrote in message
...
Klaatu wrote:
"N_Cook" wrote in message
...
Video projector without an IR R/C , originals or substitute not
available and cannot access the presets.
Setting a One-for-all so-called universal, URC 3445 in search mode
ellicited
nothing in TV/VCR/Sat/DVD sub sets, as usual. What is not
specifically stated in the URC manual is after setting in search
mode , why you press power button, and then + to advance through the
presets in the firmware, to
send power on/off codes.
I forgot to press Power in the DVD subset sequence and instead of
transmitting variously coded Power codes it must have sent various +
codes.
Anyway on DVD code 1928 the "Keystone +" box popped up on screen.
The "-" ,
Power , or no other button worked in this DVD subset mode. I intend
getting
into the URC, remove ceramic resonator, and putting about 2V rms of sig
gen
around the resonant frequency (done this before on a different URC)
and see
if that opens up more buttons , set on 1928.
Failing anything more useful from that, monitor that "+" sequence on
digital
storage scope should give the "50 KHz" pulse rate , coding clock
rate and combined model+code sequence for "+".
Then something like this circuitry of settable clock + CMOS switch
settable
PISO shift register for model code (HCT165 ?) / settable delay SR
(4557?) /
another settable PISO for buton code / gating a settable "50 KHz "
oscillator / IR diode / ( learnable remote for regular use ).
Changing switch settings for the button PISO from the known working
"+" code
to the missing ones particularly for MENU and ENTER functions in
particular
. Any flaws in this potential hack, as only thought experiment at
the moment?

ps , for the UK anyone know what is the cheapest souce of very basic
learnable remote controls?



Perhaps make and model might be made available?

And searching for that in JP1 code lists might find the codes to be
programmed
into a JP1 programmable remote.



Not listed there , but that would have spoilt my fun.
I've just captured that "+" code on a learning remote so I can play it at
will , rather than counting 105 steps on the URC . Whatever the code was the
URC sent is not stored in the URC as the same code.
So I've "learned" the 2 , to see what the difference is also.
Will have a look on a straight scope for the 2 basic timings and then DSO to
read the 0s and 1s.
I looked into the learner to see if its possible to change the resonator to
a much lower frequency to actually observe/count/time the code by swapping
IR LED to visible LED. But an 8 MHz 2 element 3 pin , I've previously done
that when I had no DSO access.

Even going down the LIRC route you still have to crack into the IR receive
hidden decoding to get started, if no listing. It would be nice to have a
general "all codes" sniffer , I was just lucky with this attempt this time .
Anyone know, if you had access to the uP of the device in question and could
put a nanoamp monitor or something in a supply line, whether you could zero
in , like cracking a combination lock