Panasonic sa-ak25

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I have this piece of.... on my bench for a few days now, its problem
is the sound is not loud enough, you have to put it to max to hear
something. My co worker is convinced its not the output ic because the
sound is not distorted, i re-did solders everywhere, still with the
same problem. someone please help. Thanks Shane.

 

[hr(bob) [email protected]]

I have this piece of.... on my bench for a few days now, its problem
is the sound is not loud enough, you have to put it to max to hear
something. My co worker is convinced its not the output ic because the
sound is not distorted, i re-did solders everywhere, still with the
same problem. someone please help. Thanks Shane.

Did you try a different loudspeaker????

 

[[email protected]]

Two pieces of information are needed. At least one would help, but
both would be better.

Is the sound low when you use the AV jacks ?

Does the TV have an indication when it is recieving a stereo
broadcast ? Is it indicating a stereo signal ? On a Panasonic it might
not, but if you have a channel you know has SAP, you can try to switch
to that.

If it reads the SAP the level coming out of the IF strip is
sufficient, and if that is the case I'd say you have an 80% chance
that the AV jacks will have low sound as well.

In that case, if you lack a print, download the datasheet for the
audio output IC. Find out just where volume control is achieved.

This is all assuming this TV is stereo, if it is not, say so because
then there is an entire different direction to take.

JURB

 

[Arfa Daily]

Two pieces of information are needed. At least one would help, but
both would be better.

Is the sound low when you use the AV jacks ?

Does the TV have an indication when it is recieving a stereo
broadcast ? Is it indicating a stereo signal ? On a Panasonic it might
not, but if you have a channel you know has SAP, you can try to switch
to that.

If it reads the SAP the level coming out of the IF strip is
sufficient, and if that is the case I'd say you have an 80% chance
that the AV jacks will have low sound as well.

In that case, if you lack a print, download the datasheet for the
audio output IC. Find out just where volume control is achieved.

This is all assuming this TV is stereo, if it is not, say so because
then there is an entire different direction to take.

JURB

I think you'll find that this "TV", is actually a hi-fi ...

To the OP. I guess you have got the speakers in the right set of jacks and
the right way round ? With their red / black / blue / grey terminals, it's
easy to get the connections confused on one of these, if you're not using
its original speakers with the matching 4 coloured wires. Use the blue (-)
and grey (+) terminals if you are testing with 'normal' 2 wire speakers. The
unit is also mutable from the handset only, so if it has been muted, and you
don't have the handset, then it might still be in that condition. I really
can't remember if it de-mutes after a full power down, or if the volume is
adjusted. Might be worth a look though. The RSN series output hybrid used on
these is not the most reliable, but they are expensive, so if you do get to
suspecting it, be pretty sure first ...

Note that headphone switching is carried out at the RSN, pin 8, which should
be at 0v. CP503 pin 12 is where it comes in. Might be worth checking that
there is nothing amiss with either the headphone socket, or its solder
joints, as I seem to recall that it pulls that line to pin 8 down via a
grounding switch built into it. If that switch or a solder joint on it goes
bad, the line is pulled up to rail, and the unit mutes. If you get to
needing the schematics for this part of the circuit, mail me direct
off-group, and I'll see what I can do for you.

Arfa

 

[[email protected]]

I think you'll find that this "TV", is actually a hi-fi ...

To the OP. I guess you have got the speakers in the right set of jacks and
the right way round ? With their red / black / blue / grey terminals, it's
easy to get the connections confused on one of these, if you're not using
its original speakers with the matching 4 coloured wires. Use the blue (-)
and grey (+) terminals if you are testing with 'normal' 2 wire speakers. The
unit is also mutable from the handset only, so if it has been muted, and you
don't have the handset, then it might still be in that condition. I really
can't remember if it de-mutes after a full power down, or if the volume is
adjusted. Might be worth a look though. The RSN series output hybrid used on
these is not the most reliable, but they are expensive, so if you do get to
suspecting it, be pretty sure first ...

Note that headphone switching is carried out at the RSN, pin 8, which should
be at 0v. CP503 pin 12 is where it comes in. Might be worth checking that
there is nothing amiss with either the headphone socket, or its solder
joints, as I seem to recall that it pulls that line to pin 8 down via a
grounding switch built into it. If that switch or a solder joint on it goes
bad, the line is pulled up to rail, and the unit mutes. If you get to
needing the schematics for this part of the circuit, mail me direct
off-group, and I'll see what I can do for you.

Arfa- Hide quoted text -

- Show quoted text -

thanks a lot for your input guys. that was one thing we checked was
the headphone jack, we've seen that problem before, where the micro
thinks theres a jack plugged in so it cuts the sound to the speakers.
but no it wasn't that. There's another control ic that was muting the
sound, but not completely, it was like a half mute. anyways the
headache is over. This was my first post, seems to work nicely thanks
again, ill be sure to stick around Shane.