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YETI50 Set to Work

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  • YETI50 Set to Work

    The IT manager at work built himself a Ceriatone Yeti 50.
    When he tried to power it up it did'nt work and the output tubes red plated so he sent it home with me to do the set to work.
    There was absolutely no way I was going to fault find it and set to work without a schematic - so trace was done, see attached.
    The main problem was the layout diagram, to which it was built, shows the output tranny primary leads swapped from what they need to be, so it oscillated.
    Also found several wiring ommisions but no actual wiring errors from his build.
    All running now and he is happy.
    I put the voltage readings I got onto the schematic trace for future reference.
    Cheers,
    Ian
    Attached Files

  • #2
    Good looking schematics. Is that a control labeled "pussy trim"?

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    • #3
      Um, sure looks like it.
      Education is what you're left with after you have forgotten what you have learned.

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      • #4
        Thanks for the investigation.
        Absolutely hate schematic less projects.

        Got any demo showing how it sounds?
        What´s pussy trim supposed to do?
        Is it an internal trimmer or a user accesible pot?
        As shown it has the possibility of fully muting sound.
        Juan Manuel Fahey

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        • #5
          Education is what you're left with after you have forgotten what you have learned.

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          • #6
            subtle

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            • #7
              Th PT control is a user control but on the rear panel. It is a gain trim / volume control.
              I think it will mainly allow you to trim the level of "overdrive" by affecting the signal level into the clipping zener diodes after the following gain stage + cathode follower.
              Think of it as Gain 2.5 if you like.
              Cheers,
              Ian

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              • #8
                Calling that a loop is being a bit generous! I can see why people complain about it. Nice schematic and some good ideas in there to pilfer. It certainly has a lot of tonal options that's for sure.

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                • #9
                  Quite Right - So many amps come with similar "loops" (line out /line in or effects out/effects in).

                  No attempt to provide proper signal levels or output impedance. If you seriously wanted to use the effects loop then add one of the bufferd effects loop boards that various kit supliers offer.

                  Cheers,
                  Ian

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                  • #10
                    Old thread, but worth a shot. What were the omissions you found in the layout? I'm gonna start building one of these and yep... there's no schematic, just a layout.

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                    • #11
                      The layout is OK except for the output transformer primary connections, you need to check if the layout diagram has been corrected.
                      That is why I put the date of the layout diagram on the schematics I drew. If your layout diagram still has that date then the primary connections to the output tubes are shown swapped from what they need to be.
                      Follow what I put on the schematic.
                      When I said ommisions I meant ommisions by the guy who did the build, not ommisions from the layout diagram.
                      There are several places where adjacent pins on the board have to be joined. The builder missed those and left them out.
                      He has been very happy with it - once I got it going for him.
                      Cheers,
                      Ian

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                      • #12
                        Originally posted by Gingertube View Post
                        The layout is OK except for the output transformer primary connections, you need to check if the layout diagram has been corrected.
                        That is why I put the date of the layout diagram on the schematics I drew. If your layout diagram still has that date then the primary connections to the output tubes are shown swapped from what they need to be.
                        Follow what I put on the schematic.
                        When I said ommisions I meant ommisions by the guy who did the build, not ommisions from the layout diagram.
                        There are several places where adjacent pins on the board have to be joined. The builder missed those and left them out.
                        He has been very happy with it - once I got it going for him.
                        Cheers,
                        Ian
                        Awesome, thank you. Yes, Ceriatone updated their layout to swap the OT primaries. Your schematics are great.

                        I have a Chupacabra, which is the same amp (slight voicing change) and it sounds great. But I'm gonna build my own voiced a little differently.

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                        • #13
                          Also, are you missing a cap in the DC Heater supply? According to the the layouts (and the amp I have in front of me), there is a third 4700uF cap in there that I don't see in your schematic. Unless I'm missing something?

                          Last edited by FourT6and2; 05-31-2017, 01:02 AM.

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                          • #14
                            Good Catch,
                            Yes I missed the output cap after the voltage reg for the heater DC supply.
                            Also you could use the more readily available 5V regulator IC and put 2 series connected diodes in the common circuit (GND pin) to 0V to give 5V +2 x 0.7V = 6.4 V for heater.
                            Cheers,
                            Ian

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