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Behringer V-amp Popping faint output

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  • #1

    Behringer V-amp Popping faint output

    Hey guys, Probably not worth it, but decided to try anyhow. I have a Behringer v-amp pro rack, that worked great since I've had it. I sold on evilbay. Guy received and said it didn't work, sent back etc... Anyway it is now dead. I tried all inputs, tightened all grounds, cleaned with Deoxit, etc... and all I get is a very faint output when master is maxed. It also pops very loudly, when switching the s1, s2, L1, L2, output settings. I examined the circuit and shows nothing burnt etc.... Level of volume is the same through headphones, all line outs. Unit changes amp models and effects fine and otherwise seems functional across the unit. Bad Ic, Op amp, cold solder joint? I have no prob gutting the thing but wanted some guidance first. Thanks as always, you guys are awesome.
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  • #2
    probably a bad op amp. Go down the row looking for DC on an output pin.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      I figured, Is the module mounted to the back of the unit, with a small heat sink an op amp? The force is telling me that is the problem, but will do what you said . Sorry again for newbness, I'm learning. I got that Marshall rocking again, so there is hope for me. Lol

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      • #4
        Op amps are little integrated circuit chips. Some are 8-leg, like the 4580, and some are 14-leg, like the TL074. Look up a data sheet if you are unsure of the pinout.

        And when you find a bad one, it will require changing it out on the circuit board. Are you prepared to change a tiny surface mount IC?
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Hey Enzo, I have been out of the loop with issues, blah blah. Anyway I finally got around to gutting the v-amp and about the only thing I could change out is, IC9. The dual sided cicuit board makes it very difficult to bust out the tube amp iron. LOl. I did not anticipate the solder joints being so tiny. I can see why they are so cheap now. I can see the hair dryer soldering all over the place. Amazing how small things are now. It makes it virtually impossible for us diy'ers to work on this stuff. W/out the proper tools anyway. Thanks again Enzo.

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          • #6
            That is called surface mount technology. Your cell phones are made that way, the hard disc drive in your computer is made that way, hell, most of your computer is made that way.

            Look up "Chip Quik"
            Education is what you're left with after you have forgotten what you have learned.

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            • #7
              I know, it's crazy, but cheap. Less employee's too! I've disassembled and reassembled many a hard drive to save someone's data. I have been working on computers for 15 years, but they are so easy. If a motherboard or pci card is shot the bios will let you know. Toss the bad part and replace. All done, and all compatible. Pro audio is crazy proprietary and now built to throw away. Kinda sad, I miss the old quality and craftsmanship that was put into building a piece of gear. I finally made the decision to buy only plentiful vintage stuff. Sounds better and most of it is still kicking. Rocktron stuff seems to always stay alive forever, Marshall too. All these companies seem to be reinventing the wheel over and over, just making it smaller and cheaper, trying to retain quality instead of improving it. Making ice cream out of s@@@. My 2 cents. Thanks Enzo.

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              • #8
                The IC mounted on the rear of the unit is a 5V regulator. There should be 10-12 volts AC feeding the board from the two orange wires, rectified by four diodes. The input voltage should be about 12 volts, the output being 5 volts. There are only 3 connections to the IC - the centre being ground (0v). A meter check on the other two legs should validate it's operation.

                If the unit is lighting up then this IC should be working , as this is the only means of supply to this section of board. There is another pair of yellow wires from the transformer to the audio board, output being about 37 volts total, (yellow/yellow).

                I could do with a schematic of this unit if anyone has one, I have a poorly V-Amp Pro in dire need of repair as well. Mine is definately a control board problem, as it does not boot.

                Regards

                Nick

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                • #9
                  Dont mention it

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                  • #10
                    Hi Nik, welcome to the board.

                    behr schematics are tough to come by. If you google, don;t be arfraid to dive down 5 or 6 pages to find something. You might find it.

                    As service centers we all have to sign non-disclosure agreements. so the schematics are confidential.

                    I have a dead V-amp Pro here, also with a dead CPU board. We wound up just sending a piece of B-stock to the customer.

                    As to the V-amp, if it has control board problems, better hope it is solder. You won;t likely be finding those LSIs.
                    Education is what you're left with after you have forgotten what you have learned.

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