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Guitar synth fails self test

Discussion in 'Troubleshooting and Repair' started by glen, May 25, 2018.

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  1. glen

    glen

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    Apr 3, 2016
    Hi folks,I have a guitar synth that is acting strangely.Did the internet searches for the usual suspects and eventually came across it's "service notes".In the "notes" which doesn't cover much I found that the unit can perform some self tests so I ran them and believe it was test #3 that it did not pass.Anywho the test is to check midi output(the unit acts irratically ,sometimes some strings won't sound,sometimes they all do,but the vol is always so low that I have to run the the guitar and the amp almost wide open and it's still not enough volume).The service notes do list 2 ic's to check but I cannot locate them on the block diagram or the parts list.there are not a lot of ic's in this(maybe 10)so I am wondering if there is some way to check the ic's in this unit and maybe find the culprit.Must warn you that I know next to nothing about electronics(I do have a multi-meter tho if that helps:).Also my brother does electronic repairs but he is very busy guy so seeing if I can sort this myself.Appreciate any info or advice,thanks,Glen.
     
  2. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Let me guess........ hmmmmm.......... nope, my crystal ball fu is none existent tonight. It seems there's absolutely no way I can detect the make, the model, the schematic or the board layout no matter how I throw my Tarot cards down......

    :rolleyes:
     
    73's de Edd likes this.
  3. glen

    glen

    6
    1
    Apr 3, 2016
  4. kellys_eye

    kellys_eye

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    Jun 25, 2010
  5. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Test #3 relates to the MIDI functions - did you 'loop through' the MIDI in/out ports?
     
  6. kellys_eye

    kellys_eye

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    Jun 25, 2010
    I get to at LEAST 45 IC's.......
     
  7. kellys_eye

    kellys_eye

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    Jun 25, 2010
    Have you checked your leads?
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Hey, they actually give you a schematic. That's impressive!
     
  9. kellys_eye

    kellys_eye

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    Their keenness to supply schematics is inversely proportional to the chances of you fixing it.
     
  10. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Sir glen . . . . .

    If all of the Rockin' Rolands very special bells and whistles operate and it's just very low audio . . . . . .

    All roads tend to lead to Rome . . . . and to Adobe page 14 and its IC46 . . . . .TDA1313T . . . with its inputs and outputs and as to to whether Q24, 25 and 29 mute transistors might possibly be having an unwanted base bias, presently being upon them.

    73's de Edd
    .....
     
  11. glen

    glen

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    1
    Apr 3, 2016
    thanks for all the comments everybody,pretty clear that this is way over my head.Believe I will have to bug my buddy with electronics repair background.At least I can give him a good start as to what to look at.If my bud can fix this I will post back exactly what he had to do in case someone else runs into this it may help them out.thanks again will be in touch,Glen.
     
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