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...and all of the sudden, no sound!

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  • likeandrot
    I just recently moved to Japan from the Seattle area and brought a couple treasured items along to create with, the Mono/Poly being one of them. So today, I
    Message 1 of 14 , May 27, 2010
      I just recently moved to Japan from the Seattle area and brought a couple treasured items along to create with, the Mono/Poly being one of them. So today, I was recording with the MonoPoly playing in poly mode while adjusting the filter and the sound very quickly faded out. No nothing from any of the oscillators the filter or the noise gen. I can however hear a very quiet sound of maybe the ADSR when I play the keys. Just so all possible information is present I want to also note that I was powering it through a newly purchased step up transformer (not sure if that could have had any effect on my precious)


      I also have a couple keys that don't work -it's not just dirty contacts either. It looks like the contacts for those keys are corroded somehow. Is it possible to find or repair the contact board?

      Please, any help would be greatly appreciated!

      thank you,
      chad
    • Alan Dicker
      From your description it sounds like you filter chip SSM2044 may have gone.  you pick then up for around 25 euro.  as for the contacts do you mean it seems
      Message 2 of 14 , May 27, 2010
        From your description it sounds like you filter chip SSM2044 may have gone.  you pick then up for around 25 euro.  as for the contacts do you mean it seems that the rubber contact has corroded or the PCB contact?  You night find the rubber strips on ebay. same type as in the polysix and another few keyboards.  as for finding a complete keyboard PCB that might be more tricky.
         
        Alan

        --- On Thu, 27/5/10, likeandrot <likeandrot@...> wrote:

        From: likeandrot <likeandrot@...>
        Subject: [korg_mono-poly] ...and all of the sudden, no sound!
        To: korg_mono-poly@yahoogroups.com
        Date: Thursday, 27 May, 2010, 11:11

         
        I just recently moved to Japan from the Seattle area and brought a couple treasured items along to create with, the Mono/Poly being one of them. So today, I was recording with the MonoPoly playing in poly mode while adjusting the filter and the sound very quickly faded out. No nothing from any of the oscillators the filter or the noise gen. I can however hear a very quiet sound of maybe the ADSR when I play the keys. Just so all possible information is present I want to also note that I was powering it through a newly purchased step up transformer (not sure if that could have had any effect on my precious)

        I also have a couple keys that don't work -it's not just dirty contacts either. It looks like the contacts for those keys are corroded somehow. Is it possible to find or repair the contact board?

        Please, any help would be greatly appreciated!

        thank you,
        chad


      • Florian Anwander
        Hi Alan ... first he should check whether there is a signal at pin 1 (input) of the SSM2044 Also it is worth checking the four ICs 2033 at pin 8, 3 and 12
        Message 3 of 14 , May 27, 2010
          Hi Alan

          > From your description it sounds like you filter chip SSM2044 may have
          > gone.
          first he should check whether there is a signal at pin 1 (input) of the
          SSM2044
          Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
          there is a signal.


          > mean it seems that the rubber contact has corroded or the PCB contact?
          > You night find the rubber strips on ebay. same type as in the polysix
          > and another few keyboards. as for finding a complete keyboard PCB that
          > might be more tricky.
          check also http://www.oldcrows.net/~oldcrow/synth/korg/polysix/keyclean.html

          If the contacts don't work ever, then maybe also some of the diodes in
          the keyboard matrix might have died.

          Florian
        • chad imes
          it s the PCB that s corroded somehow -like the previous owner spilt a soft drink on it or something? Soooo, is it possible to check these things using a DMM?
          Message 4 of 14 , May 27, 2010
            it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?

            Soooo, is it possible to check these things using a DMM?  0_o  That's all I got.

            thanks again,
            chad




            From: Florian Anwander <fanwander@...>
            To: korg_mono-poly@yahoogroups.com
            Sent: Thu, May 27, 2010 8:39:38 PM
            Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

             

            Hi Alan

            > From your description it sounds like you filter chip SSM2044 may have
            > gone.
            first he should check whether there is a signal at pin 1 (input) of the
            SSM2044
            Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
            there is a signal.

            > mean it seems that the rubber contact has corroded or the PCB contact?
            > You night find the rubber strips on ebay. same type as in the polysix
            > and another few keyboards. as for finding a complete keyboard PCB that
            > might be more tricky.
            check also http://www.oldcrows.net/~oldcrow/synth/korg/polysix/keyclean.html

            If the contacts don't work ever, then maybe also some of the diodes in
            the keyboard matrix might have died.

            Florian


          • Alan Dicker
            got any pictures?  it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to
            Message 5 of 14 , May 27, 2010
              got any pictures?  it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to uneaven to give good contact over the the pad.  testing the curcuit by simply holding a wier over the connection in place of the rubber pad might help you determin of the pads non conductive any more but as Florain said it may be the associated diode thats faild.  those diodes are very cheap parts to get.
               
              I take it the board and rubber contacts have all been cleaned in the past?
               

              --- On Thu, 27/5/10, chad imes <likeandrot@...> wrote:

              From: chad imes <likeandrot@...>
              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
              To: korg_mono-poly@yahoogroups.com
              Date: Thursday, 27 May, 2010, 13:18

               
              it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?

              Soooo, is it possible to check these things using a DMM?  0_o  That's all I got.

              thanks again,
              chad




              From: Florian Anwander <fanwander@mnet- online.de>
              To: korg_mono-poly@ yahoogroups. com
              Sent: Thu, May 27, 2010 8:39:38 PM
              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

               
              Hi Alan

              > From your description it sounds like you filter chip SSM2044 may have
              > gone.
              first he should check whether there is a signal at pin 1 (input) of the
              SSM2044
              Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
              there is a signal.

              > mean it seems that the rubber contact has corroded or the PCB contact?
              > You night find the rubber strips on ebay. same type as in the polysix
              > and another few keyboards. as for finding a complete keyboard PCB that
              > might be more tricky.
              check also http://www.oldcrows .net/~oldcrow/ synth/korg/ polysix/keyclean .html

              If the contacts don't work ever, then maybe also some of the diodes in
              the keyboard matrix might have died.

              Florian


            • chad imes
              thanks Alan and Florian! I ll take pictures of the PCB so you can see. One point I m still not clear on is how I might test the output of the SSM 2044 and the
              Message 6 of 14 , May 27, 2010
                thanks Alan and Florian!

                I'll take pictures of the PCB so you can see.  

                One point I'm still not clear on is how I might test the output of the SSM 2044 and the 2033s.  Can that be done with a DMM or in another easy cheap way?

                thank you very very much!!!

                chad 


                From: Alan Dicker <alanmdicker@...>
                To: korg_mono-poly@yahoogroups.com
                Sent: Thu, May 27, 2010 11:09:43 PM
                Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                 

                got any pictures?  it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to uneaven to give good contact over the the pad.  testing the curcuit by simply holding a wier over the connection in place of the rubber pad might help you determin of the pads non conductive any more but as Florain said it may be the associated diode thats faild.  those diodes are very cheap parts to get.
                 
                I take it the board and rubber contacts have all been cleaned in the past?
                 

                --- On Thu, 27/5/10, chad imes <likeandrot@yahoo. com> wrote:

                From: chad imes <likeandrot@yahoo. com>
                Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                To: korg_mono-poly@ yahoogroups. com
                Date: Thursday, 27 May, 2010, 13:18

                 
                it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?

                Soooo, is it possible to check these things using a DMM?  0_o  That's all I got.

                thanks again,
                chad




                From: Florian Anwander <fanwander@mnet- online.de>
                To: korg_mono-poly@ yahoogroups. com
                Sent: Thu, May 27, 2010 8:39:38 PM
                Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                 
                Hi Alan

                > From your description it sounds like you filter chip SSM2044 may have
                > gone.
                first he should check whether there is a signal at pin 1 (input) of the
                SSM2044
                Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
                there is a signal.

                > mean it seems that the rubber contact has corroded or the PCB contact?
                > You night find the rubber strips on ebay. same type as in the polysix
                > and another few keyboards. as for finding a complete keyboard PCB that
                > might be more tricky.
                check also http://www.oldcrows.net/~oldcrow/synth/korg/polysix/keyclean.html

                If the contacts don't work ever, then maybe also some of the diodes in
                the keyboard matrix might have died.

                Florian



              • Alain
                ...I want to also note that I was powering it through a newly purchased step up transformer... Japan s household power is 100v A.C. if I m not mistaken. Your
                Message 7 of 14 , May 27, 2010
                  "...I want to also note that I was powering it through a newly purchased
                  step up transformer..."

                  Japan's household power is 100v A.C. if I'm not mistaken. Your step up transformer is listed as what ? 100v to 120v A.C. ? If it says anything else, like 120v to 240V then it will certainly damage your MP4.

                  Also, it sounds very much like your SSM2044 has died. In case this would also happen to me, I've purchased a replacement recently on an Ebay store in China for about $10 (including shipping!). It arrived quickly and in perfect condition and is now in my MP4 working fine, the date stamp is 1987. I have kept the original (date stamp 1982) as a back-up now.

                  These chips are 28 years old after all, and they were manufactured in an era where reliability rates were quite low. I'm surprised that they've lasted that long ! I only hope none of the SSM2033 in my MP4 dies, because these chips are impossible to find, unless taken from another non-working MP4.

                  Good luck.
                  Alain.


                  --- In korg_mono-poly@yahoogroups.com, "likeandrot" <likeandrot@...> wrote:
                  >
                  > I just recently moved to Japan from the Seattle area and brought a couple treasured items along to create with, the Mono/Poly being one of them. So today, I was recording with the MonoPoly playing in poly mode while adjusting the filter and the sound very quickly faded out. No nothing from any of the oscillators the filter or the noise gen. I can however hear a very quiet sound of maybe the ADSR when I play the keys. Just so all possible information is present I want to also note that I was powering it through a newly purchased step up transformer (not sure if that could have had any effect on my precious)
                  >
                  >
                  > I also have a couple keys that don't work -it's not just dirty contacts either. It looks like the contacts for those keys are corroded somehow. Is it possible to find or repair the contact board?
                  >
                  > Please, any help would be greatly appreciated!
                  >
                  > thank you,
                  > chad
                  >
                • Alain
                  This is who I bought a replacement SSM2044 from. Excellent Ebayer.
                  Message 8 of 14 , May 27, 2010
                    This is who I bought a replacement SSM2044 from. Excellent Ebayer.

                    http://cgi.ebay.com/1-x-IC-Chip-SSM2044-4-Pole-Voltage-Controlled-DIP-16pin-/180393142562?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2a0044e922

                    --- In korg_mono-poly@yahoogroups.com, "likeandrot" <likeandrot@...> wrote:
                    >
                    > I just recently moved to Japan from the Seattle area and brought a couple treasured items along to create with, the Mono/Poly being one of them. So today, I was recording with the MonoPoly playing in poly mode while adjusting the filter and the sound very quickly faded out. No nothing from any of the oscillators the filter or the noise gen. I can however hear a very quiet sound of maybe the ADSR when I play the keys. Just so all possible information is present I want to also note that I was powering it through a newly purchased step up transformer (not sure if that could have had any effect on my precious)
                    >
                    >
                    > I also have a couple keys that don't work -it's not just dirty contacts either. It looks like the contacts for those keys are corroded somehow. Is it possible to find or repair the contact board?
                    >
                    > Please, any help would be greatly appreciated!
                    >
                    > thank you,
                    > chad
                    >
                  • Alan Dicker
                    One thing to test is can your filter self oscillate with the res right up?  the resonance feedback is all on chip with the 2044 so if it can do that your
                    Message 9 of 14 , May 28, 2010

                      One thing to test is can your filter self oscillate with the res right up?  the resonance feedback is all on chip with the 2044 so if it can do that your chip is bad.
                       
                      A digital multi meter wont really cut it re testing the correct tool to use is an Oscilloscope.
                      If you don have one of those....
                       
                      try bellow methods at your own risk.
                       
                      Many might disagree with me her and I would like to say be very careful while working this way but I often find that if no oscilloscope is available that simply testing the signal path with a wire attached to the tip of an audio jack will tell you allot.
                      it is a rather gorilla method and you need steady hands to work this way as if you touch or short out something you shouldn't it could cost you allot more than a SSM 2044.
                       
                      Audio comes in to pin 1 of the 2044.  if you follow this trace from pin one to the first resistor leg it meets you can hold your wire there and see if you here anything?  I would recommend having your monopoly arps running in poly mode so you don't have to hit the keys your self.
                      Also remember that the signal level at this point will be quite different from the final output stage.  most likely allot higher so start with the level of your gear quite low to safe guard your speakers and amp.
                      you should here un-filtered VCOs.
                      pin 3 is the audio out.  test here with the same method.  if your chip were working you would here something if not your chip is dead.  I suspect the chip is dead anyway.  with a dead chip you would still here a slight noise of the final amp envelope open and close when monitoring at high volume as this stage comes after the filter.
                       
                      remember though 2044s are cheap to get comped to allot of SSM chips so its really worth getting a few installing a socket and swapping out the old one rather than poking around and causing more damage.
                      --- On Fri, 28/5/10, chad imes <likeandrot@...> wrote:

                      From: chad imes <likeandrot@...>
                      Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                      To: korg_mono-poly@yahoogroups.com
                      Date: Friday, 28 May, 2010, 0:21

                       
                      thanks Alan and Florian!

                      I'll take pictures of the PCB so you can see.  

                      One point I'm still not clear on is how I might test the output of the SSM 2044 and the 2033s.  Can that be done with a DMM or in another easy cheap way?

                      thank you very very much!!!

                      chad 


                      From: Alan Dicker <alanmdicker@ yahoo.co. uk>
                      To: korg_mono-poly@ yahoogroups. com
                      Sent: Thu, May 27, 2010 11:09:43 PM
                      Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                       
                      got any pictures?  it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to uneaven to give good contact over the the pad.  testing the curcuit by simply holding a wier over the connection in place of the rubber pad might help you determin of the pads non conductive any more but as Florain said it may be the associated diode thats faild.  those diodes are very cheap parts to get.
                       
                      I take it the board and rubber contacts have all been cleaned in the past?
                       

                      --- On Thu, 27/5/10, chad imes <likeandrot@yahoo. com> wrote:

                      From: chad imes <likeandrot@yahoo. com>
                      Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                      To: korg_mono-poly@ yahoogroups. com
                      Date: Thursday, 27 May, 2010, 13:18

                       
                      it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?

                      Soooo, is it possible to check these things using a DMM?  0_o  That's all I got.

                      thanks again,
                      chad




                      From: Florian Anwander <fanwander@mnet- online.de>
                      To: korg_mono-poly@ yahoogroups. com
                      Sent: Thu, May 27, 2010 8:39:38 PM
                      Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                       
                      Hi Alan

                      > From your description it sounds like you filter chip SSM2044 may have
                      > gone.
                      first he should check whether there is a signal at pin 1 (input) of the
                      SSM2044
                      Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
                      there is a signal.

                      > mean it seems that the rubber contact has corroded or the PCB contact?
                      > You night find the rubber strips on ebay. same type as in the polysix
                      > and another few keyboards. as for finding a complete keyboard PCB that
                      > might be more tricky.
                      check also http://www.oldcrows .net/~oldcrow/ synth/korg/ polysix/keyclean .html

                      If the contacts don't work ever, then maybe also some of the diodes in
                      the keyboard matrix might have died.

                      Florian




                    • Florian Anwander
                      Hello Alan ... I do this all the time, the way you are describing (and I think most technicians do it that way). Use only extremely simple speakers or
                      Message 10 of 14 , May 28, 2010
                        Hello Alan

                        > Many might disagree with me her and I would like to say be very careful
                        > while working this way but I often find that if no oscilloscope is
                        > available that simply testing the signal path with a wire attached to
                        > the tip of an audio jack will tell you allot.
                        I do this all the time, the way you are describing (and I think most
                        technicians do it that way). Use only extremely simple speakers or
                        headphones for this, because there may signal transitions happen, which
                        can kill tweeters or delicate headphones! I have a set of old car hifi
                        speakers on my workbench for this.

                        Florian
                      • Alan Dicker
                        Good to know Im not alone ... From: Florian Anwander Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound! To:
                        Message 11 of 14 , May 28, 2010
                          Good to know Im not alone

                          --- On Fri, 28/5/10, Florian Anwander <fanwander@...> wrote:

                          From: Florian Anwander <fanwander@...>
                          Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                          To: korg_mono-poly@yahoogroups.com
                          Date: Friday, 28 May, 2010, 10:32

                           
                          Hello Alan

                          > Many might disagree with me her and I would like to say be very careful
                          > while working this way but I often find that if no oscilloscope is
                          > available that simply testing the signal path with a wire attached to
                          > the tip of an audio jack will tell you allot.
                          I do this all the time, the way you are describing (and I think most
                          technicians do it that way). Use only extremely simple speakers or
                          headphones for this, because there may signal transitions happen, which
                          can kill tweeters or delicate headphones! I have a set of old car hifi
                          speakers on my workbench for this.

                          Florian

                        • chad imes
                          so per your fine advice I didn t even test anything I just went straight to replacing the 2044 (there was already a socket installed) and now my darling
                          Message 12 of 14 , Jun 9, 2010
                            so per your fine advice I didn't even test anything I just went straight to replacing the 2044 (there was already a socket installed) and now my darling analogue princess sings again!

                            thank you so much!!!!


                            From: Alan Dicker <alanmdicker@...>
                            To: korg_mono-poly@yahoogroups.com
                            Sent: Fri, May 28, 2010 5:55:44 PM
                            Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                             


                            One thing to test is can your filter self oscillate with the res right up?  the resonance feedback is all on chip with the 2044 so if it can do that your chip is bad.
                             
                            A digital multi meter wont really cut it re testing the correct tool to use is an Oscilloscope.
                            If you don have one of those....
                             
                            try bellow methods at your own risk.
                             
                            Many might disagree with me her and I would like to say be very careful while working this way but I often find that if no oscilloscope is available that simply testing the signal path with a wire attached to the tip of an audio jack will tell you allot.
                            it is a rather gorilla method and you need steady hands to work this way as if you touch or short out something you shouldn't it could cost you allot more than a SSM 2044.
                             
                            Audio comes in to pin 1 of the 2044.  if you follow this trace from pin one to the first resistor leg it meets you can hold your wire there and see if you here anything?  I would recommend having your monopoly arps running in poly mode so you don't have to hit the keys your self.
                            Also remember that the signal level at this point will be quite different from the final output stage.  most likely allot higher so start with the level of your gear quite low to safe guard your speakers and amp.
                            you should here un-filtered VCOs.
                            pin 3 is the audio out.  test here with the same method.  if your chip were working you would here something if not your chip is dead.  I suspect the chip is dead anyway.  with a dead chip you would still here a slight noise of the final amp envelope open and close when monitoring at high volume as this stage comes after the filter.
                             
                            remember though 2044s are cheap to get comped to allot of SSM chips so its really worth getting a few installing a socket and swapping out the old one rather than poking around and causing more damage.
                            --- On Fri, 28/5/10, chad imes <likeandrot@yahoo. com> wrote:

                            From: chad imes <likeandrot@yahoo. com>
                            Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                            To: korg_mono-poly@ yahoogroups. com
                            Date: Friday, 28 May, 2010, 0:21

                             
                            thanks Alan and Florian!

                            I'll take pictures of the PCB so you can see.  

                            One point I'm still not clear on is how I might test the output of the SSM 2044 and the 2033s.  Can that be done with a DMM or in another easy cheap way?

                            thank you very very much!!!

                            chad 


                            From: Alan Dicker <alanmdicker@ yahoo.co. uk>
                            To: korg_mono-poly@ yahoogroups. com
                            Sent: Thu, May 27, 2010 11:09:43 PM
                            Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                             
                            got any pictures?  it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to uneaven to give good contact over the the pad.  testing the curcuit by simply holding a wier over the connection in place of the rubber pad might help you determin of the pads non conductive any more but as Florain said it may be the associated diode thats faild.  those diodes are very cheap parts to get.
                             
                            I take it the board and rubber contacts have all been cleaned in the past?
                             

                            --- On Thu, 27/5/10, chad imes <likeandrot@yahoo. com> wrote:

                            From: chad imes <likeandrot@yahoo. com>
                            Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                            To: korg_mono-poly@ yahoogroups. com
                            Date: Thursday, 27 May, 2010, 13:18

                             
                            it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?

                            Soooo, is it possible to check these things using a DMM?  0_o  That's all I got.

                            thanks again,
                            chad




                            From: Florian Anwander <fanwander@mnet- online.de>
                            To: korg_mono-poly@ yahoogroups. com
                            Sent: Thu, May 27, 2010 8:39:38 PM
                            Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                             
                            Hi Alan

                            > From your description it sounds like you filter chip SSM2044 may have
                            > gone.
                            first he should check whether there is a signal at pin 1 (input) of the
                            SSM2044
                            Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
                            there is a signal.

                            > mean it seems that the rubber contact has corroded or the PCB contact?
                            > You night find the rubber strips on ebay. same type as in the polysix
                            > and another few keyboards. as for finding a complete keyboard PCB that
                            > might be more tricky.
                            check also http://www.oldcrows.net/~oldcrow/synth/korg/polysix/keyclean.html

                            If the contacts don't work ever, then maybe also some of the diodes in
                            the keyboard matrix might have died.

                            Florian





                          • Alan Dicker
                            Great news,  and how handy to have a socket there already.  I would assume quite a few MP4s will have had a socket put in by now.   Alan ... From: chad imes
                            Message 13 of 14 , Jun 9, 2010
                              Great news,  and how handy to have a socket there already.  I would assume quite a few MP4s will have had a socket put in by now.
                               
                              Alan

                              --- On Wed, 9/6/10, chad imes <likeandrot@...> wrote:

                              From: chad imes <likeandrot@...>
                              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                              To: korg_mono-poly@yahoogroups.com
                              Date: Wednesday, 9 June, 2010, 10:14

                               
                              so per your fine advice I didn't even test anything I just went straight to replacing the 2044 (there was already a socket installed) and now my darling analogue princess sings again!

                              thank you so much!!!!


                              From: Alan Dicker <alanmdicker@ yahoo.co. uk>
                              To: korg_mono-poly@ yahoogroups. com
                              Sent: Fri, May 28, 2010 5:55:44 PM
                              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                               

                              One thing to test is can your filter self oscillate with the res right up?  the resonance feedback is all on chip with the 2044 so if it can do that your chip is bad.
                               
                              A digital multi meter wont really cut it re testing the correct tool to use is an Oscilloscope.
                              If you don have one of those....
                               
                              try bellow methods at your own risk.
                               
                              Many might disagree with me her and I would like to say be very careful while working this way but I often find that if no oscilloscope is available that simply testing the signal path with a wire attached to the tip of an audio jack will tell you allot.
                              it is a rather gorilla method and you need steady hands to work this way as if you touch or short out something you shouldn't it could cost you allot more than a SSM 2044.
                               
                              Audio comes in to pin 1 of the 2044.  if you follow this trace from pin one to the first resistor leg it meets you can hold your wire there and see if you here anything?  I would recommend having your monopoly arps running in poly mode so you don't have to hit the keys your self.
                              Also remember that the signal level at this point will be quite different from the final output stage.  most likely allot higher so start with the level of your gear quite low to safe guard your speakers and amp.
                              you should here un-filtered VCOs.
                              pin 3 is the audio out.  test here with the same method.  if your chip were working you would here something if not your chip is dead.  I suspect the chip is dead anyway.  with a dead chip you would still here a slight noise of the final amp envelope open and close when monitoring at high volume as this stage comes after the filter.
                               
                              remember though 2044s are cheap to get comped to allot of SSM chips so its really worth getting a few installing a socket and swapping out the old one rather than poking around and causing more damage.
                              --- On Fri, 28/5/10, chad imes <likeandrot@yahoo. com> wrote:

                              From: chad imes <likeandrot@yahoo. com>
                              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                              To: korg_mono-poly@ yahoogroups. com
                              Date: Friday, 28 May, 2010, 0:21

                               
                              thanks Alan and Florian!

                              I'll take pictures of the PCB so you can see.  

                              One point I'm still not clear on is how I might test the output of the SSM 2044 and the 2033s.  Can that be done with a DMM or in another easy cheap way?

                              thank you very very much!!!

                              chad 


                              From: Alan Dicker <alanmdicker@ yahoo.co. uk>
                              To: korg_mono-poly@ yahoogroups. com
                              Sent: Thu, May 27, 2010 11:09:43 PM
                              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                               
                              got any pictures?  it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to uneaven to give good contact over the the pad.  testing the curcuit by simply holding a wier over the connection in place of the rubber pad might help you determin of the pads non conductive any more but as Florain said it may be the associated diode thats faild.  those diodes are very cheap parts to get.
                               
                              I take it the board and rubber contacts have all been cleaned in the past?
                               

                              --- On Thu, 27/5/10, chad imes <likeandrot@yahoo. com> wrote:

                              From: chad imes <likeandrot@yahoo. com>
                              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                              To: korg_mono-poly@ yahoogroups. com
                              Date: Thursday, 27 May, 2010, 13:18

                               
                              it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?

                              Soooo, is it possible to check these things using a DMM?  0_o  That's all I got.

                              thanks again,
                              chad




                              From: Florian Anwander <fanwander@mnet- online.de>
                              To: korg_mono-poly@ yahoogroups. com
                              Sent: Thu, May 27, 2010 8:39:38 PM
                              Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!

                               
                              Hi Alan

                              > From your description it sounds like you filter chip SSM2044 may have
                              > gone.
                              first he should check whether there is a signal at pin 1 (input) of the
                              SSM2044
                              Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
                              there is a signal.

                              > mean it seems that the rubber contact has corroded or the PCB contact?
                              > You night find the rubber strips on ebay. same type as in the polysix
                              > and another few keyboards. as for finding a complete keyboard PCB that
                              > might be more tricky.
                              check also http://www.oldcrows .net/~oldcrow/ synth/korg/ polysix/keyclean .html

                              If the contacts don't work ever, then maybe also some of the diodes in
                              the keyboard matrix might have died.

                              Florian






                            • Alain
                              Woohoo! Great news! Now, if all repairs could be that simple ? By the way, mine too had a socket already installed... You will notice, however, that your
                              Message 14 of 14 , Jun 9, 2010
                                Woohoo! Great news! Now, if all repairs could be that simple ?
                                By the way, mine too had a socket already installed...

                                You will notice, however, that your beloved MP4 filter might behave a little differently than before. This is due to the fact that each new 2044 replacement, it would ideally require a re-calibration of the filter section to re-adjust for maximum resonance, self-oscillation threshold, full range of the cutoff, maximum level of modulation, and so on... Since each SSM2044 is a linear circuit and they each behave slightly differently.

                                That being said, it might also behave close enough to your old one and not need any significant re-adjustments. Mine needed to be re-calibrated. Yours might not.

                                Anyway, the most important thing is: it's alive again !

                                Alain.


                                --- In korg_mono-poly@yahoogroups.com, chad imes <likeandrot@...> wrote:
                                >
                                > so per your fine advice I didn't even test anything I just went straight to replacing the 2044 (there was already a socket installed) and now my darling analogue princess sings again!
                                >
                                > thank you so much!!!!
                                >
                                >
                                >
                                > ________________________________
                                > From: Alan Dicker <alanmdicker@...>
                                > To: korg_mono-poly@yahoogroups.com
                                > Sent: Fri, May 28, 2010 5:55:44 PM
                                > Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                                >
                                >
                                >
                                > One thing to test is can your filter self oscillate with the res right up? the resonance feedback is all on chip with the 2044 so if it can do that your chip is bad.
                                >
                                > A digital multi meter wont really cut it re testing the correct tool to use is an Oscilloscope.
                                > If you don have one of those....
                                >
                                > try bellow methods at your own risk.
                                >
                                > Many might disagree with me her and I would like to say be very careful while working this way but I often find that if no oscilloscope is available that simply testing the signal path with a wire attached to the tip of an audio jack will tell you allot.
                                > it is a rather gorilla method and you need steady hands to work this way as if you touch or short out something you shouldn't it could cost you allot more than a SSM 2044.
                                >
                                > Audio comes in to pin 1 of the 2044. if you follow this trace from pin one to the first resistor leg it meets you can hold your wire there and see if you here anything? I would recommend having your monopoly arps running in poly mode so you don't have to hit the keys your self.
                                > Also remember that the signal level at this point will be quite different from the final output stage. most likely allot higher so start with the level of your gear quite low to safe guard your speakers and amp.
                                > you should here un-filtered VCOs.
                                > pin 3 is the audio out. test here with the same method. if your chip were working you would here something if not your chip is dead. I suspect the chip is dead anyway. with a dead chip you would still here a slight noise of the final amp envelope open and close when monitoring at high volume as this stage comes after the filter.
                                >
                                > remember though 2044s are cheap to get comped to allot of SSM chips so its really worth getting a few installing a socket and swapping out the old one rather than poking around and causing more damage.
                                > --- On Fri, 28/5/10, chad imes <likeandrot@yahoo. com> wrote:
                                >
                                >
                                > >From: chad imes <likeandrot@yahoo. com>
                                > >Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                                > >To: korg_mono-poly@ yahoogroups. com
                                > >Date: Friday, 28 May, 2010, 0:21
                                > >
                                > >
                                > >
                                > >thanks Alan and Florian!
                                > >
                                > >
                                > >I'll take pictures of the PCB so you can see.
                                > >
                                > >
                                > >One point I'm still not clear on is how I might test the output of the SSM 2044 and the 2033s. Can that be done with a DMM or in another easy cheap way?
                                > >
                                > >
                                > >thank you very very much!!!
                                > >
                                > >
                                > >chad
                                > >
                                > >
                                > >
                                > ________________________________
                                > From: Alan Dicker <alanmdicker@ yahoo.co. uk>
                                > >To: korg_mono-poly@ yahoogroups. com
                                > >Sent: Thu, May 27, 2010 11:09:43 PM
                                > >Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                                > >
                                > >
                                > >got any pictures? it may be that the pads have carodid to the piont wher the metirial don;t conduct properley or it might be just that the surface is to uneaven to give good contact over the the pad. testing the curcuit by simply holding a wier over the connection in place of the rubber pad might help you determin of the pads non conductive any more but as Florain said it may be the associated diode thats faild. those diodes are very cheap parts to get.
                                > >
                                > >I take it the board and rubber contacts have all been cleaned in the past?
                                > >
                                > >
                                > >--- On Thu, 27/5/10, chad imes <likeandrot@yahoo. com> wrote:
                                > >
                                > >
                                > >>From: chad imes <likeandrot@yahoo. com>
                                > >>Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                                > >>To: korg_mono-poly@ yahoogroups. com
                                > >>Date: Thursday, 27 May, 2010, 13:18
                                > >>
                                > >>
                                > >>
                                > >>it's the PCB that's corroded somehow -like the previous owner spilt a soft drink on it or something?
                                > >>
                                > >>
                                > >>Soooo, is it possible to check these things using a DMM? 0_o That's all I got.
                                > >>
                                > >>
                                > >>thanks again,
                                > >>chad
                                > >>
                                > >>
                                > >>
                                > >>
                                > >>
                                > >>
                                > >>
                                > ________________________________
                                > From: Florian Anwander <fanwander@mnet- online.de>
                                > >>To: korg_mono-poly@ yahoogroups. com
                                > >>Sent: Thu, May 27, 2010 8:39:38 PM
                                > >>Subject: Re: [korg_mono-poly] ...and all of the sudden, no sound!
                                > >>
                                > >>
                                > >>Hi Alan
                                > >>
                                > >>> From your description it sounds like you filter chip SSM2044 may have
                                > >>> gone.
                                > >>first he should check whether there is a signal at pin 1 (input) of the
                                > >>SSM2044
                                > >>Also it is worth checking the four ICs 2033 at pin 8, 3 and 12 whether
                                > >>there is a signal.
                                > >>
                                > >>> mean it seems that the rubber contact has corroded or the PCB contact?
                                > >>> You night find the rubber strips on ebay. same type as in the polysix
                                > >>> and another few keyboards. as for finding a complete keyboard PCB that
                                > >>> might be more tricky.
                                > >>check also http://www.oldcrows.net/~oldcrow/synth/korg/polysix/keyclean.html
                                > >>
                                > >>If the contacts don't work ever, then maybe also some of the diodes in
                                > >>the keyboard matrix might have died.
                                > >>
                                > >>Florian
                                > >>
                                > >>
                                > >
                                > >
                                >
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