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Thread: Ampeg SVT3 Pro Line Out Schematic (Not svt3proa) or just IC6

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    Ampeg SVT3 Pro Line Out Schematic (Not svt3proa) or just IC6

    I have searched the forums quite a bit looking for the Schematic for the Line Out board for the Ampeg SVT3 Pro. All of the schematics I find are for the SVT 3 Pro A board. Those schematics are missing "IC6" Pretty much everything else is there.

    The IC6 on this line out board is totally melted. No way to read the top. Any help would be great.

    I have attached a picture of the board with an arrow pointing to specifically what Im looking for
    Click image for larger version. 

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    Supporting Member Jazz P Bass's Avatar
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    Verify that pin 4 is -Vdc & pin 8 is +Vdc.
    If so, pop in a 4558 or somesuch opamp.
    Although a 5532 will have better drive capabilities.

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    Supporting Member Jazz P Bass's Avatar
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    I may have found the schematic.
    It indicates a TL072 opamp.

    http://music-electronics-forum.com/t31725/#post306684
    Attached Files Attached Files

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    Supporting Member Jazz P Bass's Avatar
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    On your board pic, R110 looks like it got a bit toasty.

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    Thank you so much! I'll give it a look. Yes R110 is trashed, as well as 2 of the capacitors and possibly a Diode. I'm hoping that those are the only problems I find.

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    Supporting Member Jazz P Bass's Avatar
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    You have to wonder what got plugged in where!

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    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by Jazz P Bass View Post
    You have to wonder what got plugged in where!
    Tesla coil?

    Click image for larger version. 

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    Juan Manuel Fahey

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    Seriously. One of the musicians I help out brought this to me and asked if I could take a look at it. I'm wondering if some dirty phantom power got sent in through the DI.

    Or a Tesla Coil.. You never really know LOL

    I should also mention that I found a burnt trace on the board running to a capacitor. I'll have to bridge around it in the rebuild. Fortunately it is a 1 layer board.

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    So I have:
    Contacted Ampeg. Turns out that there is a "Version 1" and "Version 2" for this particular amp. I am servicing the original. A different company (SLM) owned ampeg. The company that owns them now does not have the schematics for the V1.

    They're best guess was a TL072 as well. I have replaced 2 caps, a resistor and the opamp. Amplifier still does not show LEDs on the front and if I don't lift the ground I get a weird oscillation via the Sound board from the Line-Out XLR.

    Fans and Tubes Turn on and Light up. Any other suggestions? Maybe a different opamp? other diagnostics suggestions?

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    Caught my first break. Apparently Whoever originally took this amp apart (I received it in pieces) broke the top off of the op amp. I just found the top by accident. It is a 5532D JRC. I've also opened a Support ticket with LS Electronics (Some of the guys that built this amp work there). If the correct opamp doesn't work, I'll send it in to them.

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