Announcement

Collapse
No announcement yet.

Carlsbro Viper 100 W bass combo - need Schematic

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Carlsbro Viper 100 W bass combo - need Schematic

    I am trying to get a second hand Carlsbro Viper 100 W Bass Combo to work and need the schematics.
    It continues to blow the internal fuse and help on the wiring would be appreciated.

    Click image for larger version

Name:	25530720_10212828817569383_1353486900_o.jpg
Views:	1
Size:	102.7 KB
ID:	873159Click image for larger version

Name:	25485316_10212828817689386_1724400665_o.jpg
Views:	1
Size:	101.8 KB
ID:	873160Click image for larger version

Name:	25530352_10212828817769388_889100989_o.jpg
Views:	1
Size:	72.8 KB
ID:	873161

  • #2
    How do I identify a replacement trafo in place of the one that is currently in the amp ? I have removed the transformer and when I test it the secondary current alternates from -5 to + 5 Volt DC. That cant be right but how do I find out the voltage that the unit needs....

    https://youtu.be/CJjgpnaTMm8

    Any help is appreciated

    /Henrik Lynge

    Comment


    • #3
      Transformers make AC volts, not DC volts.

      Does the transformer blow a fuse when not connected to the circuit board? If not, then why do we think the transformer needs replacing?
      Education is what you're left with after you have forgotten what you have learned.

      Comment


      • #4
        When I measure the secondary current as VAC the output is 34,8 Vac between blue and green and 70 Vac between blue and brown.
        Isnt that quite high or is that normal ? the problem is that when i connect it to the board the two internal fuse (2,5 A) blow emmediatly.
        How to proceed ?

        Comment


        • #5
          So the transformer is not the problem, the board is.

          My educated guess is you have shorted output transistors. Those 2N3055s.

          Further down the list would be the bridge rectifier - the black square.

          And further down, a shorted filter cap - the two dark blue cylinders.
          Education is what you're left with after you have forgotten what you have learned.

          Comment


          • #6
            should I start by replacing the two 2N3055s or can I measure if they are the reason ?

            Comment


            • #7
              And the video shows values jumping from 0.05VDC to -0.05VDC (100 times smaller than the +/-5VDC you think you see) , essentially *zero* DC volts, for the very good reason that there is NO DC there and the meter simply is "hunting" trying to find "some".

              Try setting meter to, say, 200VAC scale and remeasure, I bet you´ll find near 30VAC on each secondary half.

              EDIT: lots of posts in the last 5 or 10 minutes.

              OK, the transformer is fine, and supplies 35+35VAC, quite normal for a 100W amplifier.
              I guess Green is the center tap, Blue and Brown are the 35VAC ends.

              To start:
              1) build a lamp bulb limiter. It won´t "repair" your amplifier but will avoid 2.5A fuses blowing for now and let you start measuring something.
              Use a 60W or so bulb, a "real filament" 60W one, not a LED or CFL lamp which claims to be "equivalent to a 60W bulb".
              We are interested in the metallic filament inside the bulb, not light output.
              One of semi-modern "small quartz bulb inside a larger glass envelope" type is fine.


              2) plugged into limiter, transformer fully reconnected as original, with all controls on 0, no speaker connected, no 2.5A fuses (yet) , turn amp on, measure that some 35VAC (might be less because of the bulb limiter) reach the fuse sockets.
              Bulb limiter should blink and then turn off or stay red or dark orange, indicating reasonably low idle consumption.
              If it shines bright, then transformer might be bad, but I don´t think it is.

              3) turn amp off, unplug it for safety, reset both fresh 2.5A fuses, then plug into limiter and turn amp on.
              I guess now bulb will glow bright, indicating a short.

              Test and report.
              Last edited by J M Fahey; 12-17-2017, 11:28 PM.
              Juan Manuel Fahey

              Comment


              • #8
                Don't just start replacing things, we ALWAYS want to know what is wrong. Yes, measure those transistors to see if they are shorted.
                Education is what you're left with after you have forgotten what you have learned.

                Comment


                • #9
                  It's blowing fuses because he has 2 of the transformer lugs connected via cable to the thermal breaker by the output transistors.

                  edit: never mind, an unused transformer lug is being used as a tie-point. Thermal breaker is in series with PT primary.
                  Last edited by g1; 12-18-2017, 07:49 PM.
                  Originally posted by Enzo
                  I have a sign in my shop that says, "Never think up reasons not to check something."


                  Comment


                  • #10
                    When measuring the two transistors there is no resistance between the emmitor and collector and it doesnt change when I short the emmitor and the base so I guess that they are both gone. - more testing before I change them ???


                    Comment for G1: I dont think that that is the problem, the third leg from that right on the trafo is only used to create a loop and connects no where on the trafo when measuring. current enters on number 2 from right, are connecting a loop with temp switch on three from right and exit on 1 from left

                    I I I I I
                    + -+ -

                    /Henrik Lynge
                    Last edited by hlynge; 12-18-2017, 06:22 AM.

                    Comment


                    • #11
                      Test with limiter executed:

                      1) build a lamp bulb limiter. - done with a halogen 116 W = 150 W


                      2) Measuring on the incomming side of the fuse (that is not there) I get 68,5 V on both "channels" crossing and 35 V from midle

                      3) You are right that when putting back the fuses I get a bright light from the bulb so i have a short https://youtu.be/Pdq-DMYVRWA
                      Last edited by hlynge; 12-18-2017, 04:58 PM.

                      Comment


                      • #12
                        Originally posted by hlynge View Post
                        Comment for G1: I dont think that that is the problem, the third leg from that right on the trafo is only used to create a loop and connects no where on the trafo when measuring. current enters on number 2 from right, are connecting a loop with temp switch on three from right and exit on 1 from left
                        Ok. Sorry about that. You mentioned in the other thread that you thought the PT wiring was wrong so I wanted to verify that with resistance checks first. I see you have done that and the primary wiring is correct.
                        Originally posted by Enzo
                        I have a sign in my shop that says, "Never think up reasons not to check something."


                        Comment


                        • #13
                          Originally posted by hlynge View Post
                          When measuring the two transistors there is no resistance between the emmitor and collector and it doesnt change when I short the emmitor and the base so I guess that they are both gone. - more testing before I change them ???
                          When you say 'no resistance' do you mean zero ohms or open circuit?
                          If you mean zero ohms, remove the power transistors and check them again out of circuit.
                          Originally posted by Enzo
                          I have a sign in my shop that says, "Never think up reasons not to check something."


                          Comment


                          • #14
                            When testing out of circuit I find that there is Zero Ohm resistance between the emmitor and collector. There is no change in ressistance when I connect the Emmitor to the base.

                            What replacement part should I use. There are two options for 2N3055:

                            2N3055G, Transistor, NPN 15 A 60 V HFE:5 2,5 MHz, 3 ben, TO-204

                            2N3055AG, Transistor, NPN 15 A 60 V HFE:5 1 MHz, 2 ben, TO-204AA

                            More I should test before I replace the two transistors ?

                            Comment


                            • #15
                              Exchanging the two x 2N3055 was what was needed for the amp to work again. Have been practicing with the band this evening with no problems )

                              Comment

                              Working...
                              X