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  • Traynor ycv40 low output

    i have a traynor ycv40 pcb version 9 with 1k sine into input I cannot get much more than 3 volts into a 8 ohm dummy load. i have replaced the power supply caps all of them. Also found 6.3 volts on tranny was actually 4 volts, so I subbed a 6.3 vac source in.
    Any help or suggestion invited. Tomorrow i will scope the inputs of v1,2,3,4,5

    v1 voltages pin1 150vdc pin6 139 vdc heaters 6.3 vdc
    v2 pin1 153 vdc pin6 155vdc heaters here are 5.7 vdc
    v3 pin1 45 vdc pin6 135 vdc heaters here are 6.3 vac

    v4 pin3 390 vdc pin4 385 vdc pin5 -38
    v5 pin3 388 vcd pin4 384 vdc pin5 -40

    PT
    wc7 wc8 24 VAC
    wc9 300 VAC

    OT
    wc11 410

    Let me know what if anything else I need to provide. Correct schematic for this amp provided by traynor

    schematic-M581-1V8.pdf

    Thanks,
    Jason
    soldering stuff that's broken, breaking stuff that works, Yeah!

  • #2
    When faced with a low output I always look at the power tube grid Vac signal level.

    If it's low, then the problem is before that section.

    If it is not low: output tubes & OT is all that there is.

    Comment


    • #3
      just throwing this out there...... on a lot of those combos the signal path goes across the ic'sthat drive the effects loop and the one that drive the reverb, so if that ic dies the signal path goes with it. I've had to replace that tl072 in a couple of those amps. just a thought
      Last edited by supawah; 10-27-2014, 04:29 AM.

      Comment


      • #4
        V3 pin1 voltage is not right. Should be very similar to pin 6 voltage. Check R43 or bad solder somewhere to pin1.
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


        Comment


        • #5
          Ahh, the Fender 'let's eat the PI plate resistor' trick.

          Comment


          • #6
            Was that 4VAC heater voltage with the leads disconnected?
            Originally posted by Enzo
            I have a sign in my shop that says, "Never think up reasons not to check something."


            Comment


            • #7
              Originally posted by g-one View Post
              Was that 4VAC heater voltage with the leads disconnected?
              That was checking voltage at the tube pins 2 an 7 I think. But it also measured 4 volts disconnected. Power in is 120 volts on a variac.

              Jason
              soldering stuff that's broken, breaking stuff that works, Yeah!

              Comment


              • #8
                Was R43 bad?
                Originally posted by Enzo
                I have a sign in my shop that says, "Never think up reasons not to check something."


                Comment


                • #9
                  Originally posted by g-one View Post
                  Was R43 bad?
                  Yes it was open, replaced it with a half watt 82 k previous one looked like a 1/4 watt(used what i had). Will have time to test tomorrow and update. i tell ya kids will wear you out.

                  Thanks,
                  Jason
                  soldering stuff that's broken, breaking stuff that works, Yeah!

                  Comment


                  • #10
                    update. Hooked it up great volume and squeel swapped OT leads. Volume is as should be now.

                    Thanks a whole lot guys. I really appreciate it.

                    So now back to address the heaters . If I wanted to permanently mount a 6.3 volt transformer in there somewhere, only 3 tubes run off it 2 outputs an PI. It would need to be 2.1 amps or higher correct?

                    Thanks,
                    Jason
                    soldering stuff that's broken, breaking stuff that works, Yeah!

                    Comment


                    • #11
                      You are correct. In this amp the DC the other preamp tubes run their heaters off is taken from a different PT winding.
                      Originally posted by Enzo
                      I have a sign in my shop that says, "Never think up reasons not to check something."


                      Comment


                      • #12
                        So is 2.1amps good or should I raise the bar to 3? Or do tubes only pull the mA specified in data sheet?

                        Thanks,
                        Jason
                        soldering stuff that's broken, breaking stuff that works, Yeah!

                        Comment


                        • #13
                          The heater current remains constant, close to what the data sheet says, but you should probably leave some leeway. Your choices are probably for either 2 or 3 amps, maybe there is a 2.5A available. I would say to go with 2.5 or 3. This also leave option for adding an extra preamp tube or some other power tubes that need more heater current.
                          Originally posted by Enzo
                          I have a sign in my shop that says, "Never think up reasons not to check something."


                          Comment


                          • #14
                            Okay I'll ask the obvious question here. Now that the other problems are fixed does the amp still need the new filament supply to work?

                            Comment


                            • #15
                              Originally posted by 52 Bill View Post
                              Okay I'll ask the obvious question here. Now that the other problems are fixed does the amp still need the new filament supply to work?
                              Yes. still only getting 4 volts at the output heaters. voltage is the same 4 at the transformer connection also.

                              Jason
                              soldering stuff that's broken, breaking stuff that works, Yeah!

                              Comment

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