From: Holland Guldberg (HGuldberg@uascwa.com)
Date: 04/04/00-01:22:37 PM Z
I hooked mine up this way:
1) Get some Belden 3 wire shielded audio cable.
2) Solder the ground wire to a smaller gauge wire (keep it short); then to
pin 14 on the LM4835
3) Solder a .47 uF cap to the end of the black and red (left an right) wires
4) Solder small gauge wire (keep them short) to the other ends of the caps.
The line out signals from pins 9 (right) and 13 (left) go directly to
surface mount resistors. This is handy b/c it provides an easy place to
solder to. On of the resistors is R127 I believe. You need to solder to the
Right side of R127, and the left side of the other one. My reference view is
looking at the resistors so the R127 text reads normally.
You can find the other resistor by following the trace from pin 9. It goes
away from the LM4835 and hits what is called a "via" and then it connect to
the resistor. Make sure you solder to the correct side of the resistors,
b/c I messed up and had no signal coming out of the right channel. It was
b/c I soldered onto the wrong side.
__________---9 |
/ |
o via |LM4835
__/ |
solder here for | |
right channel---> [R unknown] ---13|
| -14| <-ground
|
|______________
[R 127]
^
|
solder here for left channel
I think this diagram is correct. I do not have my i-opener open, but I juts
did this yesterday. Sorry I don't have a digital camera. Be careful, I may
have left and right mixed up...
It is easy to verify which side of the resistors to solder to if you have a
multimeter.
Last step: Take your other end of the Belden cable, strip the ends, and
connect it to a 1/8" female plug.
Tip: Right
Ring: Left
Sleeve: Ground
Holland.
> -----Original Message-----
> From: Greg Daly [mailto:gdaly@u.washington.edu]
> Sent: Monday, April 03, 2000 8:13 PM
> To: ihack@fastolfe.net
> Subject: [ihack] audio signal
>
>
> > Did anyone figure out the easiest way to get at an audio signal?
> >
> > David
>
> easiest way? not sure if I know exactly what you mean....
> read on for what
> looks like a more promising solution (at the bottom). if you
> want to do it
> by the book though, here's the yamaha datasheet (not sure if
> you've seen
> it).
>
> http://www.yamaha.com/lsi/products/pdf/4MF715E20.pdf
> pin82: outleft
> pin81: outright
> pin88: analog gnd
>
> it has to be understood that i _dont have a unit right now_ so I can't
> test this stuff out. however, if there is some noise when
> this method is
> tried, we can try
> (a) disconnecting the amp (might help)
> (b) making a filter (i can easily do that)
> the obvious disadvantage to using these pins is that they necessitate
> soldering to extremely tiny pins.
> So, David, if you don't want to do that, the below looks good:
>
> supposedly the datasheet for the amp:
> http://www.national.com/ds/LM/LM4835.pdf
>
> and when you give pin21 a logic high, it turns pins 17 and 26 into a
> line/headphone out! all you need is 3 resistors, 2 caps, a
> jack and page
> 12 of the pdf manual. :)
>
> now what I need from you guys is some good detective work --
> see, exactly,
> what pins are connected to the speaker outs.
>
> -greg
>
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