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  1. #1
    Junior Member
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    May 2010
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    how to open up the squeezebox touch?

    hi guys

    been playing for a few hours and these are my findings. i know it's still early but here you go.

    1. the digital output is better than sb3 but still can be improved.
    2. asian language characters doesn't display correctly (chinese, japanese, thai...). no problem with sb3.

    that aside, i'm trying to figure out how to open up the unit. want to see what's inside and evaluate potential for modding it, should the sonics not improve much after running in.

    anyone knows how to open up the unit? i so far managed to remove the stand and 2 other screws.

    thx!

    yeo

  2. #2
    Senior Member Phil Leigh's Avatar
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    Quote Originally Posted by yeo View Post
    hi guys

    been playing for a few hours and these are my findings. i know it's still early but here you go.

    1. the digital output is better than sb3 but still can be improved.

    yeo
    Really? - how exactly?

    Forget about SC transformers for a start...
    It's already a low-jitter design and sounds great into any properly designed DAC via 1.5m+ of correct cable. Futzing with the power supply won't change it very much.

    IMO the only way to really improve it is to run the DAC clock back into the touch (or maybe use i2s) - but that isn't really s/pdif then...


    By the way, getting it apart is easy, putting it back together is HARD... good luck! (and be very careful).
    You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal...
    Touch(wired/W7)+Teddy Pardo PSU - Audiolense 3.3/2.0+INGUZ DRC - MF M1 DAC - Linn 5103 - full Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Pekin Tuner, Townsend Supertweeters,VdH Toslink,Kimber 8TC Speaker & Chord Signature Plus Interconnect cables
    Stax4070+SRM7/II phones
    Kitchen Boom, Outdoors: SB Radio, Harmony One remote for everything.

  3. #3
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    Jun 2006
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    The S/PDIF output circuit is actually quite good, much better than what is in the SB3. The biggest bang for the buck there is to get rid of the RCA jack and put in a true 75ohm BNC. Thats going to be the biggest improvement. Not so easy to do, you have to keep the impedances to the board etc correct.

    Now as for opening it up:

    It comes in two pieces, front and back plastic case, the front has the display attached and the back has the board attached. In between is the umbilical for the display, this is two flexible PC (FPC) assemblies, one one small (for power) and one wider (for signals). These are permanently attached to the display and go into connectors on the board attached to the back. There is very little slack on these FPCs, this is the main problem with taking it apart and getting it back together.

    You have two approaches here: take the cables out of the connectors and separate the two pieces OR leave the umbilical in place unscrew the board from the back case.

    Taking the FPCs out of their connectors is quite easy, but it is a royal pain getting them back in correctly without damaging anything when putting it back together. In the other approach you keep the umbilical in place and "clamshell" the two halves, opening up a small space between them and getting a small screwdriver in to take out the screws holding the board to the back case. You do this for all four sides. All the screws are around the periphery of the board so this can be done. Be careful not to exert too much tension on the FPCs, you don't want to rip anything or cause them to come out of the connectors (the connectors are latching, the FPCs are held quite well in their grasp).

    Its hard to say which is the best approach, I've done it both ways and its about equal amount of swearing either way.

    Even if you go for the disconnect the FPCs route you still have to unscrew the board from the back, all the interesting stuff is on the side of the board between the board and back.

    Currently you have taken off the silver "foot" and the two screws that hold the front and back together. At this point the only thing holding them together is friction, there are no more fasteners or latches or any such. You just have to pull them apart. A thin blade such as a putty knife might be helpful in trying to pry them apart. Once they DO come apart make sure you don't put much tension on the FPC. You DON'T want to grab the front and back and put huge force on them, and then have them "explosively" separate and rip the FPCs out. Gentle persuasion works better.

    In addition to the above there are two twisted pair going between the front assembly and the board (the microphone and the speaker). These have connectors and are easy to remove, just make sure you draw a picture noting the orientation of the colored wires so you can put it back together the right way.

    After you have the board unscrewed from the back you have to get the board out of the back. This isn't easy. The board fits under a "lip" molded into the case, the fit is VERY tight. I found the best way to get it out is to hold the back in your fingers and use your thumbs to apply pressure to the connectors on the back, pushing them back in, this will force the board out of the back case.

    Now on to what to do once you HAVE it apart. The first thing is to bypass the caps on the analog outs, they are not needed, getting rid of them makes a big improvement in sound.

    Next I would work on the power supplies. There are two switching DC-DC converters inside, they supply the 1.2 and 1.4 volts for the processor. One of these also supplies 10V to a 5V regulator which drives the DAC chip. So even though the DAC chip is 5V it is NOT run off the main 5V supply, they did try and isolate it from what is going on inside the box.

    I would build an external supply that had two 5V supplies, one for the main input, and one very good one for the DAC chip. In addition it will provide the 1.2 and 1.4V for the CPU. You can't just replace the DC-DC converters with linear regs in the box, they would dissipate too much heat. There are no ventilation holes and its a plastic case, the heat from these regs would fry the insides.

    Next would be the oscillators. They are just regular logic gate and crystals, same as used in the SB3. The power rails in the Touch are cleaner so you DO get lower jitter, but its possible to get even better. I would build a tiny board with two low jitter SMD oscillators and a really low noise regulator and install that over the main board (there is a LITTLE room between the board and case) with very short pigtails going down to the main board to replace the crystals.

    Thats what I would do for first level mods.

    There is a lot of work that could be done on the headphone amp, but anybody REALLY into headphone listening is probably already using an external headphone amp connected to the analog outs or to an external DAC.

    That should keep you busy for awhile!

    John S.

  4. #4
    Junior Member
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    May 2010
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    9
    hi john

    thx for your detailed write-up.

    i'm still at the samge stage, trying to pull apart the case. yes, very slowly. looks like i really need a putty knife.

    yes, i want to replace the digital output rca with a bnc. i also want to see whether i could get i2s or not. see what chips are used and what i could do to get the best digital output out of it.

    i'm only using it as a digital transport so the dac and headphone amp section, i'm going to ignore it. if i could remove its power, that's even better!

    right now powering with paul hynes 5v supply for squeezebox. as i'm not using an hdd nor thumbdrive to it, paul's 1.5a supply is still sufficient.

    thx again!

    yeo

  5. #5
    Senior Member
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    Jul 2008
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    PLease keep us all informed Yeo how your getting on!

    Sounds like a good project.

  6. #6
    Junior Member
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    i managed to separate the front case from the back. i could see the 2 flexi-pcb. dang! the connectors are so tiny. i see what john is warning. either way, best way to do it is still to get the flexi pcb out of the way first.

    as i work on this, i'll update when i get the chance. i'm curious how is spdif generated. is there i2s in the first place?

    thx!

    yeo

  7. #7

    Connecting I2S and clock signals

    I am interested in modding the Touch as I did with the receiver, to bring out I2S signals with LVDS drivers and bring in slave clocks from my Dac. This requires mounting LVDS driver and receivers in the vicinity of the Touch DAC or processor. In the receiver I was also able to mount a DVI connector on the box. It seems like the room for this may not exist inside the Touch. (The receiver is WONDERFULLY spacious)

    John, you have the most experience with the insides of the Touch. Any room for such mods? If not, I will likely want to pull out the receiver circuit board to mount elsewhere (sacrificing the controller - I am very happy with SlimControl on my Windows phone and don't really use the Touch controller).

    Actually, all I want is an upgraded receiver for 88.2K and 96K files...

    Any guidance would be greatly appreciated.

    Jack Jones

  8. #8
    Senior Member
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    There IS I2S inside. The S/PDIF and I2S come directly out of the processor. They both go through reclocker flops. I don't remember if all the signals on the I2S are reclocked or just one of the clock signals.

    There is a quarter inch or so between the main board and the back case so thin boards can be added. As long as the board has SMD chips and caps (no electrolytics that stick up from the board) you should be able to add boards. I would just mount them with insulating double stick tape to the existing board.

    Jack, I'm planing on doing exactly the same thing, a small board with LVDS interfaces to feed the clocks and take the I2S out. It worked fine on the SB3. For the SB3 I just ran a pigtail cable (the rolled up twisted pair IDC cable) through one of the holes after I took out the connector. Something similar could be done with the Touch.

    The connectors for the FPCs have a latch which is on the front of the connector. Look at the part of the connector where the FPC enters, that part is actually on a hinge. You need to take a small flat blade screw driver and pry up that front piece, it will rotate up out of the way. Once its up its obvious. You can then just pull the cable out. This is the easy part.

    The hard part is putting it back together. You have to feed the cable back in, properly lining it up, push it all the way in, and then rotate the latch back down. While holding both pieces of the assembly slightly apart and trying to squeeze your fingers down in the very narrow space between sections. Small hands help here! I don't know how they assemble this in the factory!

    John S.

  9. #9

    I2S Clocks

    Thanks John,

    I wonder if you have decided whether to use your existing clocks and add a clock doubler to output to the Touch or to use double frequency clocks? I am tempted to use a clock doubler, which would be jittery, but since I am reclocking the final output to the DAC anyway with the receiver-frequency clocks, it shouldn't matter in the end. All the clock doubler circuits I know require a perfect square wave (50% duty cycle) input. My Tent clocks are not specified for duty cycle, but they look good on the scope. I wonder how sensitive you think the Touch processor is to clock jitter, and whether a doubler circuit would be good enough? Thanks for your help.

    Jack

  10. #10
    Senior Member lrossouw's Avatar
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    Quote Originally Posted by yeo View Post
    2. asian language characters doesn't display correctly (chinese, japanese, thai...). no problem with sb3.
    Try this thread: http://forums.slimdevices.com/showth...ht=asian+touch. Haven't tested it myself.
    Louis
    Last.fm

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