removing entire analogue section on squeezebox2

[Builder Brad]

OK....

I want to remove the analogue section on the squeezebox2

I have a hacksaw ready

the image shows where I intend to cut

will the patient live to tell the tale?

[Builder Brad]

joking aside, this is something I really want to do. Ideally I also want to remove any additional regulators and switchers that are not involved with the digital sections of the squeezebox.

is there anyone out there that can guide me in my obsession?

obviously my hand will be a little bit less shaky than when I marked the cut line on the image file above

[Skunk]

I don't understand wanting to saw through the board for a few reasons:

a) It will take too long to isolate with tape and plastic (to avoid debris causing a short).
b) Those holes for standoffs are nice to have there.
c)Removing that big cap might be easier and do much the same thing (though I'm not sure on that one, so you'd have to test/search). Or better yet, you could leave the big cap and remove the IC's local caps/regs/cut traces- but still have a clean 3.3V linear supply from the headphones for the clock circuit. The 3.3V for Vdd on the dac comes from the other side, so you'd have to cut that trace if you don't want any power going to it. There are a few threads with mod suggestions and connection points for the sb2 if you search..

[Builder Brad]

cheers Skunk

those are good points

If I can achieve the same effect by not resorting to making that cut, and have the option of reversing my work that would be even better.

I guess I should target the power supplies to the ICs that are involved with the analogue stages.

I have measured 12v across that 3300uf capacitor, C55 I think on the pcb, and have tried to find the IC that provides this without sccess. Does anyone know if any of the digital stages, or the display use that 12v supply. If they do not I would like to target the internal 12v switcher for removal/disabling initially before looking at other areas for making this Squeezebox completely digital.

Brad

[Bas Horneman]

http://forums.slimdevices.com/showpost.php?p=179326&postcount=2

here is a post detailing how to disable the power supply to the dac

[Builder Brad]

Hi Bas,

thank-you, unfortunately this refers to the SB3

Brad

[Skunk]

Hi Bas,

thank-you, unfortunately this refers to the SB3

Brad

There is a lot of good info here: http://www.slimdevices.com/photos/inside_squeezebox2 . It looks like c53 and c5? correspond to c11 and c10 on Sb3.

You can also see the 3/5/9V linear regs, and the inductors (L2 and L3 I believe) for the regulators that should be disabled to result in no power to c53 and c5?.

According to this diagram posted by Sean, I don't think you can remove the 12/14V supply:

AC -> 5V 2A -----> Dual ----> 3v3 (IO, wireless, logic)
SMPS | Switcher ----> 1v2 (CPU core)
|
|----> Linear reg ----> 3v3 (headphone)
|
|
|----> Switcher ----> Multiplier -----> 11VAC VFD ef
| |
| |
14VDC | |-------> 55VDC VFD vdd2
----------RC filter<-----|
|
|
|------> Linear reg ---> 9vdc (op-amps)
|
|------> Linear reg ---> 5vdc (DAC)

[Builder Brad]

Cheers Skunk

re. the 12/14v switched internal supply

on mt other Squeezebox2 that was modded by Red Wine Audio, the 14v supply is disabled by the removal of R29 and a wire is fed from the 12v battery supply to the + side of the large capacitor.

what does the 14v/12v section supply? is it only the analogue sections - u know what I am thinking...

Brad

[Builder Brad]

Ok

I have now removed the DAC IC, the op amp that supplies the headphone output, the out put op amp and the 12? mhz crystal.

The above changes have definately improved the ausio quality when using the digital output.

I want to remove the regulators that feed the analogue components. I have attached an image and marked up 3 x rega that I intend to remove, but wanted to double check here to ask if any of the indicated 1,2,3 regulators are involved with any of the digital stages b4 I remove them.

I have also marked the 12v supply trace (4), and wondered if I could just cut this, or remove the resistor shown in order to disable more analogue parts.

help

[singleended40]

Builder Brad,

I just got a SB2 and Newava SS22203 pulse transformer. I saw the picture you installed SC947-02 in your SB2 but that view was not so clear to my eyes.

Would you once again show me on which resistor R2(249 Ohm) or R3(160 Ohm)do you connect to SC947-02 pin5 and pin8. Center pin of BNC or RCA connector is connected to pin1 and ground to pin4, is that right? Newava Tx has only 1-3 and 4-5. Thanks or your time.

Regards,
Tan

[zanash]

I'm being dense here ....why can't you just unhook the dc supplies to the various stages you want to eliminate ?

[singleended40]

I just installed the Newava S22083 pulse transformer into the SB2. My first impression is this pulse transformer has more smooth detail and more musicality than the SC947-02 in my SB3. I will let it burn-in in a couple days and let see how the sound will be.