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Panasonic model CT37G24A continuing problems

This is the set that took a serious lightning hit. It was dead with a
blown fuse when I first got it. I replaced about ten components so far
in the power supply and startup circuits. The last remaining 4
problems were: that the set was stuck on one channel, the sound was
moderate and would not change, the remote would not work, and the
"action" button would not invoke the menus. I just replaced the
microprocessor and this has fixed the channel and sound problems, but
the "action" menu and the remote still will not work. My scope fell
off the cart yesterday and so its not working either so I can't look
at the output of the remote receiver. This has been a real dog. I've
tried several receivers out of other sets but I still can't get the
remote to operate. I've never found the receivers to code sensitive. I
thought that any receiver would send an adaquate signal to any
micro,.as long as it works on 5V. Is this correct? The input and
output DC voltages on the receiver are correct. This is like a
"closed" circuit with just a few components from the receiver into the
micro so I can't imagine what else could inhibit the remote from
working. Can I check the receiver with anything other than a scope?
Does anyone think that there could still be some common problems
causing these remaining two fuctions not to work? I gotta stop taking
in these lightning jobs. Thanks, Lenny
 
F

Franc Zabkar

Jan 1, 1970
0
This is the set that took a serious lightning hit. It was dead with a
blown fuse when I first got it. I replaced about ten components so far
in the power supply and startup circuits. The last remaining 4
problems were: that the set was stuck on one channel, the sound was
moderate and would not change, the remote would not work, and the
"action" button would not invoke the menus. I just replaced the
microprocessor and this has fixed the channel and sound problems, but
the "action" menu and the remote still will not work. My scope fell
off the cart yesterday and so its not working either so I can't look
at the output of the remote receiver. This has been a real dog. I've
tried several receivers out of other sets but I still can't get the
remote to operate. I've never found the receivers to code sensitive. I
thought that any receiver would send an adaquate signal to any
micro,.as long as it works on 5V. Is this correct? The input and
output DC voltages on the receiver are correct. This is like a
"closed" circuit with just a few components from the receiver into the
micro so I can't imagine what else could inhibit the remote from
working. Can I check the receiver with anything other than a scope?
Does anyone think that there could still be some common problems
causing these remaining two fuctions not to work? I gotta stop taking
in these lightning jobs. Thanks, Lenny

AFAIK, the IR signal is most often modulated on a 38kHz carrier. If
your set uses a different frequency, then the sensitivity of any 38kHz
replacement sensors may be too low.

Why not hold down the Volume key on your remote and monitor the
receiver's output with a DMM? Assuming a +5V supply rail, a continuous
pulse train should show up as a DC level somewhere between 0v and +5V.

Or you could hook up an LED to the output, buffered with a transistor
if necessary.

- Franc Zabkar
 
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