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Re: [YamahaDX] Re: DX7 Service manual + schematics

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  • Daniel Forró
    Dear friends, thanks for your thanks, that s enough :-) I m glad it was useful to you. If necessary for more of you, I can send again, or any of you who got
    Message 1 of 42 , Feb 1, 2013
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      Dear friends,

      thanks for your thanks, that's enough :-)  I'm glad it was useful to you. If necessary for more of you, I can send again, or any of you who got it can use that server for sending big files, it's easy.

      I didn't expected thanksgiving letters, as I didn't do anything special, just collected some material from internet during years and resend it to you. I have more different manuals, if somebody of you needs something, just try to ask here.

      As I've been living in Japan for last ten years, I became more aware what politeness means :-) Sorry if somebody feels offended.   

      Have a nice day!

      Daniel Forro

      P.S.: Paljon kiitoksia, Erkki!   


      On 1 Feb, 2013, at 4:46 PM, Erkki Pöyhönen wrote:



      :-)  Thank you Daniel very very much!  This time I managed to squeeze myself into the group also, 4 downloads left...

      So kind of you! Děkuju mnohokrát!  (Google translate to the rescue :-)

      Cheers, Erkki

    • jimshoppin
      It was the DAC. I replaced BA9221 with a known working one and my DX7 came to life - loud and clear :) Thanks all for the help and advice. Jim
      Message 42 of 42 , Aug 20, 2013
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        It was the DAC.

        I replaced BA9221 with a known working one and my DX7 came to life - loud and clear :)
        Thanks all for the help and advice.

        Jim

        --- In YamahaDX@yahoogroups.com, Narfman96 - Narfland Studio <narfman96@...> wrote:
        >
        > Is the output muting relay RY-1 working? These things die all the time. Make sure all of the op amps are getting 15 volts. Some get +/- 15 volts.
        >  
        > One trick tracing out an audio circuit is take a 10uf capacitor and solder it to the tip end of an old guitar cord then plug the other end into a small amplifier or even sensitive headphones. When you probe the audio circuit from the DAC through to the output you should be able to tell where it loses it. Be aware that there will be switching noise and DC offsets in some of these early signals close to the DAC so they may sound terrible.
        >  
        > Let us know how it goes....
        >
        >
        > >________________________________
        > > From: jimshoppin <jimshoppin@...>
        > >To: YamahaDX@yahoogroups.com
        > >Sent: Tuesday, July 30, 2013 9:34 AM
        > >Subject: [YamahaDX] Re: Need Tech help : My trusty Old DX7 just died on Me
        > >
        > >
        > > 
        > >
        > >I swapped out IC40 but still no joy.
        > >I don't have a scope.
        > >
        > >--- In mailto:YamahaDX%40yahoogroups.com, "Pablo H Molina Leyton" <py5phl@> wrote:
        > >>
        > >> James,
        > >> I would go far as IC40 which gets the DAC's output. Do you have a scope? That would help trace any changes on the signal level.
        > >>
        > >> --- In mailto:YamahaDX%40yahoogroups.com, "jimshoppin" <jimshoppin@> wrote:
        > >> >
        > >> > I just received a DX7 whose volume is extremely low on the Output and Headphone jacks.
        > >> >
        > >> > The volume knob is fine.
        > >> > I've replaced the battery but the problem remains.
        > >> > I've replaced IC53, IC54, IC55 and IC56 but the problem remains.
        > >> > The 560Ohm resistor is fine.
        > >> > The relay works fine.
        > >> >
        > >> > So.. is it now recommended to replace ALL the electrolytics and hope my DX7 finally starts working properly?
        > >> >
        > >> > Cheers,
        > >> > James
        > >> >
        > >> > --- In mailto:YamahaDX%40yahoogroups.com, Daniel Forró <dan.for@> wrote:
        > >> > >
        > >> > > You can find DX7 Service manual on more web pages, for example here:
        > >> > >
        > >> > > http://elektrotanya.com/?q=showresult&what=yamaha%20dx7&kategoria=&kat2=all
        > >> > >
        > >> > > If not, I can send you all I have.
        > >> > >
        > >> > > I would start with Diagnostic test, maybe it will help and reset
        > >> > > instrument if there's a software problem.
        > >> > >
        > >> > > If no improvement, go usual checking routine - power supply (fuses),
        > >> > > and I would recommend changing all electrolytic capacitors after so
        > >> > > many years in service. (I have changed all in PS and on main board
        > >> > > recently.)
        > >> > >
        > >> > > Then check usual things like all connectors (reseat or clean), reseat
        > >> > > IC's in sockets. Then output circuit from IC56, then 53, 54, 55
        > >> > > (especially trimmer VR3 near), output relay RY1 and its circuit
        > >> > > (transistor), also volume slider. But relay is probably OK, if you
        > >> > > still can hear signal.
        > >> > >
        > >> > > I'm sure you will repair it, such great instrument deserves it.
        > >> > >
        > >> > > Good luck!
        > >> > >
        > >> > > Daniel Forro
        > >> > >
        > >> > >
        > >> > > On 27 Jan, 2013, at 8:51 AM, aztech222 wrote:
        > >> > >
        > >> > > > Today I was having a blast at my music practice today with my band
        > >> > > > and bang !
        > >> > > > My trusty Old DX7 just died on me.
        > >> > > > But hey its normal its served me well, I've had 23 years and I
        > >> > > > bought it second hand ...
        > >> > > > The problem : Its has no sound output.
        > >> > > > I check my headphone output it works although weak, I think.
        > >> > > > The output can be heard a softly when i cranked the volume at maximum
        > >> > > > but its very weak. i presume its the uotput Op amp or an electroyte
        > >> > > > capacitor associated with the op amp.
        > >> > > >
        > >> > > > I can change the parts no problem but I don't have a schematic or
        > >> > > > know which part number to change can anyone help me out ?
        > >> > > >
        > >> > > > Thanks
        > >> > > >
        > >> > > > Chris
        > >> > >
        > >> >
        > >>
        > >
        > >
        > >
        >
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