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MOTU 896 mk3 re-cap

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    MOTU 896 mk3 re-cap

    Aaaaaand here we go again

    Ended up managing to "move up in the world", as it were, and upgrade my recording rig, and was fortunate enough to catch one of these babies "locally", for a smidge over half the price of a brand-new one (700eu versus 1200+)

    "Before" photos illustrate my issue (a pet-peeve, if you will) - chock full of Lelon (blue), Meritek (black), and a couple of SWC(?) and Teapos plus a JunFu in the power supply.

    Some cool design features, though - diode clamps on ALL analog inputs and outputs (in the form of those DIP-cased rectifier bridges), the casing's made out of two identical cast aluminium pieces, PGA2500's on each analog input, all opamps are Rohm BA4580R's, apart from a whole bunch of ST TS922's between the PGA's and the two CS5368 ADC's (8ch each); AKM AK4396 DAC's.

    Odd thing though, but i think they're "cheating" a bit In its internal DSP mixer, you can flip the phase, but i've got a hunch that each analog in is routed to TWO ADC channels, with opposed phases, and depending on whether the phase-flip option is active or not, the "appropriate" ADC input is selected.

    The Xilinx Spartan, my hunch is, is used mostly for routing the audio between the outside connections (analog i/o, digital i/o, computer connections) and the DSP chip (TI TMS320C6722). At least that's my (semi)educated guess, going by the traces going to and from it. The "brains" of the whole thing must be that Atmel microcontroller (AT91SAM7S256) - datasheet says it has some ARM7 core, and that 8-pin flash is nearest to it, so...
    Attached Files
    Last edited by Khron; 07-24-2015, 06:49 PM.
    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

    #2
    Re: MOTU 896 mk3 re-cap

    After - look at all them lovely Panasonics Plus a handful of Nichicons, and a Rubycon in the PSU

    Photo 1, output and AES/EBU board - 20pcs 100u/63v Panasonic FR on the analog outputs, 47u/63v Panasonic NHG's filtering the analog rails (i filled in all the unpopulated spots too, just for the heck of it), and three Panasonic FL 1800u/6.3v (last one fitted after taking the photo) on the digital rails (3.3v & 5v).

    Photo 2, power supply - 4pcs Panasonic FK 2200u/16v, an FC 22u/63v start-up cap, and a 22u/400v Rubycon WXA as the primary cap.

    Photo 3, mainboard - 47u/63v Panasonic FR's on the inputs, 4pcs Nichicon HM 1500u/16v (NOT from the '06-'07 bad batches ) and a pair of Panasonic FR 100u/63v on the analog rails, digital rails filtered by 3pcs Nichicon PL 4700u/6.3v, several HD 1500u/6.3v and a few Panasonic FL 1800u/6.3v.

    ADC's got two 330u/6.3v Sanyos each, and the output of the inverting boost (5v gets converted into -8v, which goes into a 7905 for the -5v rail, for the PGA2500's) got a Panasonic FL 1000u/16v. Phantom power got a 22u/63v Nichicon PL, and i decided to install an actual inductor at its output, as the silkscreen said (replacing the 10ohm resistor that was there).

    Couldn't be bothered even considering about replacing the SMD electrolytics, so this'll have to do for now
    Attached Files
    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

    Comment


      #3
      Re: MOTU 896 mk3 re-cap

      You didn't want to try bipolar capacitors on the outputs/inputs?
      Presonus Audiobox USB, Schiit Magni 3, Sony MDR-V700

      Comment


        #4
        Re: MOTU 896 mk3 re-cap

        Yes and no Yes, i guess it would've been interesting(?), but no, because i didn't have any in stock

        And besides, polarized ones are fine on the inputs, due to the existence (or possibility of using) phantom power. A quick datasheet check for Panasonic SU bipolars show they only go up to 50v, which is a wee bit too close for comfort, for me.
        Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

        Comment


          #5
          Re: MOTU 896 mk3 re-cap

          Anyone got any Motu schematics to share??
          I will exchange some Focusrite schematics.

          Comment


            #6
            Re: MOTU 896 mk3 re-cap

            What exactly for?
            Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

            Comment


              #7
              Re: MOTU 896 mk3 re-cap

              since I also own the 896 I also need Motu schematics to share...in case let me know by mail
              Last edited by jocondor; 02-29-2016, 11:28 AM.

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                #8
                Re: MOTU 896 mk3 re-cap

                did you also replace all op amps? which one brand and model with ?
                Last edited by jocondor; 02-29-2016, 12:21 PM.

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                  #9
                  Re: MOTU 896 mk3 re-cap

                  Khron can you please tell me which stock headphone op amps are inside the 896 cause it's impossible to read on your pics

                  Comment


                    #10
                    Re: MOTU 896 mk3 re-cap

                    I didn't / don't have any schematics available, sorry. On the other hand, though, it's not all THAT complex, imho

                    No, i haven't bothered messing with the opamps - 4580's are "low noise" to start with, and Rohm aren't exactly some no-name chinese manufacturer, so i'm ok with that :P

                    That particular area might've went a bit out of focus or something, but judging by the shade of gray and the rough outline of the fonts, they look like the opamps on the output board, ie. BA4580R's.
                    Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                    Comment


                      #11
                      Re: MOTU 896 mk3 re-cap

                      KHRON tnx for answer....in any case I want to try to replace just the first 4 output channel 4580 op amp with LM4562 and AD8066 what do you think about? Regarding the input channels which is the first device which the signal meets the PGA2500 or is there an hidden op amp which I can't see on your pic prior the PGA2500? Another question can you clearly explain what is the function of the 4 pins device DBL1036?
                      Last edited by jocondor; 02-29-2016, 03:28 PM.

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                        #12
                        Re: MOTU 896 mk3 re-cap

                        In the last photo attached to post #2, i can see there are a pair of opamps (possibly 4580's) between each input XLR and the row of relays.

                        What do i think about those? They're expensive

                        1) http://nwavguy.blogspot.fi/2011/08/o...ths-facts.html
                        2) http://nwavguy.blogspot.fi/2011/08/o...surements.html

                        The 4-pin devices are bridge rectifiers. In this case, they're used as diode clamps.

                        https://www.gearslutz.com/board/atta...a217-large.gif
                        Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                        Comment


                          #13
                          Re: MOTU 896 mk3 re-cap

                          Originally posted by Khron View Post
                          In the last photo attached to post #2, i can see there are a pair of opamps (possibly 4580's) between each input XLR and the row of relays.

                          What do i think about those? They're expensive

                          1) http://nwavguy.blogspot.fi/2011/08/o...ths-facts.html
                          2) http://nwavguy.blogspot.fi/2011/08/o...surements.html

                          The 4-pin devices are bridge rectifiers. In this case, they're used as diode clamps.

                          https://www.gearslutz.com/board/atta...a217-large.gif
                          Thanks once again for further answer ..ok do you confirm there is an op amp possibly the 4580 prior the PGA2000 in each channel ? What is its own purpose to amp the audio signal before the PGA2000? Moreover what is the function of the row of relays to select pad function and to enable the phantom power?
                          Last edited by jocondor; 02-29-2016, 04:12 PM.

                          Comment


                            #14
                            Re: MOTU 896 mk3 re-cap

                            See for yourself:

                            https://www.badcaps.net/forum/attach...4&d=1437783248

                            Actually, now that i take a closer look at that picture, the writing on those looks more similar to the ST ones that are ahead of ADC's - TS922.

                            I have no idea about the exact role of those opamps, i haven't bothered tracing out the circuit And regarding the relays, that's most likely.
                            Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                            Comment


                              #15
                              Re: MOTU 896 mk3 re-cap

                              Ok Khron thanks ...what's the weather and the temperature in Finland in these days? ..back to 896, can you tell me the role or the IC's CS 5368? They seem to be A/D converter, moreover what are the IC's which control the 8 input gain enconders ? And the IC's which drive the leds S/meter?
                              Last edited by jocondor; 03-01-2016, 02:58 AM.

                              Comment


                                #16
                                Re: MOTU 896 mk3 re-cap

                                It's the first of March, so "obviously" it's nice & wintery

                                CS5368 - see my first post. they're the ADC's, so... odds are pretty good they play the role of converting the analog input signals into digital ones Shocking, i know :P

                                Umm... Technically, the encoders are the one doing the controlling If they had motors attached to them, THEN they would be the devices that are being controlled Going by what i can see in the last picture in the 2nd post, that pin header's likely connected to that 74-series chip next to it (which i'm guessing, does some serial-to-parallel converting for the LCD & leds), which then goes into the Xilinx FPGA. I wouldn't be surprised if the encoders were multiplexed by some chip(s) on the front panel board, and then go straight into the FPGA (if not even the Atmel chip).

                                May i ask why you're so concerned with such details (which aren't really involved in the sound aspect)?
                                Khron's Cave - Electronics - Audio - Teardowns - Mods - Repairs - Projects - Music - Rants - Shenanigans

                                Comment


                                  #17
                                  Re: MOTU 896 mk3 re-cap

                                  Hi Khron I confess you I really would like to visit your country ...I will do it one day maybe...hence are the two CS5368 the ADC for the frontal 8 input channels? I guess it....so why am I so concerned with such detail ?? Just why I have to do servicing very soon in to gears like that

                                  Comment


                                    #18
                                    Re: MOTU 896 mk3 re-cap

                                    do you have bears in the forests of Filland Khron?

                                    Comment


                                      #19
                                      Re: MOTU 896 mk3 re-cap

                                      only russian ones probably.

                                      Comment


                                        #20
                                        Re: MOTU 896 mk3 re-cap

                                        Originally posted by stj View Post
                                        only russian ones probably.
                                        Here in Italy we have some ....in North and center side....and you where are you based?

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