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Thread: Need help and schematic for Ashdown 515 bass combo

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    Member fredcapo's Avatar
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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

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    Member Jon Snell's Avatar
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    Member fredcapo's Avatar
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    Thanks Jon. I did ashdown term search but did not dig enough i guess.

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    Member Jon Snell's Avatar
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    My pleasure.

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    Don't forget the joker g1's Avatar
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    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

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    Last edited by g1; 05-25-2020 at 03:00 AM.
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    pdf of old 515 and mod attached
    Attached Files Attached Files

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    Member Jon Snell's Avatar
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    Probably because it was 2013 but the main schematics are in the threads
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Jon Snell; 05-25-2020 at 09:09 AM. Reason: Added information
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    Lifetime Member Enzo's Avatar
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    We had a server crash a few years back and many files were lost. The titles remain but they contain a 1x1 pixel image.

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    Quote 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.

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    Member fredcapo's Avatar
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    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. #11
    Member Jon Snell's Avatar
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    You probably wouldn't notice any difference unless driving a very low impedance speaker.

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    Quote 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.

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