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Need help and schematic for Ashdown 515 bass combo

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  • Need help and schematic for Ashdown 515 bass combo

    Had an Ashdown 515 in the junk pile. No output. Running TIP 142/147 pair for output. One was dead, other had leakage. I removed and looked at the OC voltages on the pads ( emitters appx 46v bases millivolts, collector 2 and 6 volts ground ref). I had a tip142/147 T pair just to try. Lower power rating. The amp worked for 5 seconds then both sizzled. The pots may have been maxed. Did they burn because of the power rating or a bias issue?

    Does anyone have a schematic? Thanks

  • #2
    Already covered.
    Here; https://music-electronics-forum.com/...ad.php?t=33661
    Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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    • #3
      Thanks Jon. I did ashdown term search but did not dig enough i guess.

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      • #4
        My pleasure.
        Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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        • #5
          That file in post #2 of the linked thread is not working. The picture of the schematic in post #6 works:
          https://music-electronics-forum.com/...4&d=1373501076
          Last edited by g1; 05-25-2020, 03:00 AM.
          "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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          • #6
            pdf of old 515 and mod attached
            Attached Files
            "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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            • #7
              Probably because it was 2013 but the main schematics are in the threads
              Attached Files
              Last edited by Jon Snell; 05-25-2020, 09:09 AM. Reason: Added information
              Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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              • #8
                We had a server crash a few years back and many files were lost. The titles remain but they contain a 1x1 pixel image.
                Education is what you're left with after you have forgotten what you have learned.

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                • #9
                  Originally posted by Jon Snell View Post
                  Probably because it was 2013 but the main schematics are in the threads
                  Like Enzo said, there was a crash and a lot of the schematic download links are dead. Unfortunately you need to try downloading them before they can be trusted to add to a post.
                  Even worse, you can not re-upload the same file as one of the dead links, it will not show up. If you always zip the files you upload, then it will always work.
                  "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                  • #10
                    Regarding the mod to the Ashdown 515 changing the .22 ohm to .33 ohm... what would be the result if I used .47 ohm 5 watters...have a bunch.

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                    • #11
                      You probably wouldn't notice any difference unless driving a very low impedance speaker.
                      Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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                      • #12
                        Originally posted by fredcapo View Post
                        Regarding the mod to the Ashdown 515 changing the .22 ohm to .33 ohm... what would be the result if I used .47 ohm 5 watters...have a bunch.
                        You should do the math and calculate the mV reading across those resistors so you get the same idle current through the transistors.
                        Not a big difference but might as well. They say approx. 3mV across each of the .33R, which is around 10mA. So if using .47R, you would adjust for 4 to 5mV instead.
                        "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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