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  • Ampeg B200R

    Received an Ampeg B200R for repair and here is the status...The jack board in the back was manufactured wrong and when plugging into the "Without Horn" Jack, it blows the 4 Mosfets and the fuse. Somebody had modified the jack board ok and just replaced the fuse...and of course it blew again. I have Mosfets on order...checked all associated components there in the circuit and can't find anything else wrong...I do have one question about the circuit though...There is an opto-coupler in the output circuit and I am after seeing this on a few other different brand names of amplifiers...exactly what purpose does this serve??? (I am still in the learning stages and expect to be for quite some time). Any insight greatly appreciated....
    Cheers,
    Bernie

  • #2
    a lot of ampeg power amps use VTL5C7 opto, or Vactrol (led input, photo resistor output).
    this is used at the start of the power amp, as a limiter, to help protect the power amp if it is driven too hard.
    if the led turns on, the photoresistor goes lower in resistance, and reduces the gain of hte input stage

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    • #3
      Originally posted by mozwell View Post
      a lot of ampeg power amps use VTL5C7 opto, or Vactrol (led input, photo resistor output).
      this is used at the start of the power amp, as a limiter, to help protect the power amp if it is driven too hard.
      if the led turns on, the photoresistor goes lower in resistance, and reduces the gain of hte input stage
      Could the B200R schematic help you?
      Attached Files

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      • #4
        For some reason I can't download these schematics.

        Does anybody know what I am doing wrong?

        Thanks!

        Comment


        • #5
          Don't worry, it's some Forum problem , hope it can be addressed soon.
          It neither delivers old schematics nor new ones can be uploaded.
          Oh well.
          Juan Manuel Fahey

          Comment


          • #6
            I have been uploading 'new' attachments for the past week.
            To upload previous versions the schematic must be rescanned.

            Comment


            • #7
              Hello,

              I need to repair my B200R so i'm looking for the schematic but it seems to be impossible to download the files of "doctor". It's just a grey page with a little white square. Could anybody help me?

              Thanks.
              Cams

              Comment


              • #8
                I ended up repairing mine after without the schematics....so I don't have a copy.....have you tried contacting SLM and asking for a copy??
                What is wrong with the unit that you have??
                Cheers,
                Bernie

                Comment


                • #9
                  SLM sold the Crate and Ampeg lines to Loud Technologies quite a few years ago. They will have the schematics at Loud.


                  A server crash on this forum scrambled most of our posted files.
                  Education is what you're left with after you have forgotten what you have learned.

                  Comment


                  • #10
                    SLM sold the Crate and Ampeg lines to Loud Technologies quite a few years ago. They will have the schematics at Loud.


                    A server crash on this forum scrambled most of our posted files.
                    Education is what you're left with after you have forgotten what you have learned.

                    Comment


                    • #11
                      I ended up repairing mine after without the schematics....so I don't have a copy.....have you tried contacting SLM and asking for a copy??
                      What is wrong with the unit that you have??
                      Cheers,
                      Bernie

                      Comment


                      • #12
                        i hope this helps
                        Attached Files

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                        • #13
                          Sorry Enzo...I meant to say Loud not SLM.......
                          Cheers.....

                          Comment


                          • #14
                            Originally posted by bsco View Post
                            Received an Ampeg B200R for repair and here is the status...The jack board in the back was manufactured wrong and when plugging into the "Without Horn" Jack, it blows the 4 Mosfets and the fuse. Somebody had modified the jack board ok and just replaced the fuse...and of course it blew again. I have Mosfets on order...checked all associated components there in the circuit and can't find anything else wrong...I do have one question about the circuit though...There is an opto-coupler in the output circuit and I am after seeing this on a few other different brand names of amplifiers...exactly what purpose does this serve??? (I am still in the learning stages and expect to be for quite some time). Any insight greatly appreciated....
                            Cheers,
                            Bernie
                            Big issue is solder connections. The parts tend to vibrate and break their own solder joints.

                            Loud, not SLM...? what's the difference?
                            It's become pretty obvious to me that the two are related...
                            Last edited by soundguruman; 05-16-2014, 04:13 PM.

                            Comment


                            • #15
                              Originally posted by soundguruman View Post
                              Big issue is solder connections. The parts tend to vibrate and break their own solder joints.

                              Loud, not SLM...? what's the difference?
                              It's become pretty obvious to me that the two are related...
                              The one I had didn't have that problem. It needed a mod to the output jack board...as far as bad connections go I see the same in the Ampegs...full of them...even the so-called American made ones.....I guess all parts tend to vibrate and break their own solder joints at some point in time...

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