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Mesa mark v diode problem

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  • Mesa mark v diode problem

    I found a bad diode on my amp after having what i thought was a bad rectifier tube and cant find the picture i took.it is d55 on v7.could someone post a picture of the correct location right or left.thanks.i think i will wait until i have the correct diode as i was going to try a 4148.could wreck the fuse.i hope nothing went along with this part or i will probably have it checked over.

  • #2
    You'll get faster results if you can post or link a schematic.
    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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    • #3
      Ok sounds good i will find it on my phone.https://el34world.com/Forum/index.php?topic=11865.0 attachments were not uploading yhis should work.pg7
      Last edited by qwerty; 08-28-2018, 12:47 AM.

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      • #4
        Pdf
        Attached Files
        Last edited by qwerty; 08-29-2018, 11:07 PM.

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        • #5
          It could be that I'm blind, but I don't see a D55 anywhere.
          "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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          • #6
            I forgot its on the board not shematic.going into v7a it says 12 volts.
            Attached Files
            Last edited by qwerty; 08-29-2018, 11:00 PM.

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            • #7
              Originally posted by qwerty View Post
              I forgot its on the board not shematic.going into v7a it says 12 volts.
              Maybe one of the series 12V zeners (type 4742) in the 24V supply, but these don't seem to connect to V7a. There is a chain of 4x15V zeners (1N4744) connected to the input cap of V7a though.
              Last edited by Helmholtz; 08-29-2018, 01:41 PM.
              - Own Opinions Only -

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              • #8
                Yep its the 4752.i found the 2 ik r near it one righr and left.easy way would be to look at another amp.i wonder if i could put in a diode rectifier plug to prevent this for now on.this one diode was protecting i guess the amp.since i liked the diode setting on the amp.v7 should be rectifier because 6 is driver 12ax7.
                Attached Files
                Last edited by qwerty; 08-29-2018, 10:58 PM.

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