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  • #1

    DC30 clone issues

    I just finished a dc30 clone. I have having a static issue when I turn the ch1 volume all the way up. I posted a video on youtube of exactly what it is doing. The static sound is at time stamp 2:32 . The rest of the video is me trying to explain exactly what the problem is. I already changed guitars, cables and tubes. It only does it on CH1 NOT on CH2. If anyone gets a chance, can you please look at the video and try to help me out.

    https://www.youtube.com/watch?v=agvi6FF5zdg
    Last edited by gerry113377; 02-25-2020, 11:09 AM.
    Tags: None
  • #2
    Please post a schematic, or link to the schematic for your amp.
    If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

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    • #3
      What SoulFetish said, and it sure sounds like parasitic oscillation to me...

      Justin
      "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
      "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
      "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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      • #4
        Originally posted by Justin Thomas View Post
        What SoulFetish said, and it sure sounds like parasitic oscillation to me...

        Justin
        Without seeing a schematic and judging by the clip, that's my initial suspicion as well, and would investigate an issue with the lead dress (wiring/soldering).
        If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

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        • #5






          Last edited by gerry113377; 02-25-2020, 08:00 AM.

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          • #6


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            • #7
              Sorry for the multiple post as I just figured out how to post pictures, the schematics are in the posts above.
              Last edited by gerry113377; 02-25-2020, 08:04 AM.

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              • #8
                The schematic and layout you posted is not a Ceriatone, and is significantly different. I used the Ceriatone layout on my Dizzy 30 and had no problems. Ceriatone doesn’t offer a schematic but you can find a Matchless DC30 schematic on the web, and it’s fairly close.

                http://www.ceriatone.com/ceriatone/w...0Ceriatone.jpg

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                • #9
                  Ok, I took out that part of the post. I put that on there because I didn't know how to post pictures of the schematic yet and I felt it was similar enough to be able to troubleshoot the issue. The major difference is the lack of choke and rectifier tubes. I do notice that the master volume and master tone cut are wired different and the ceriatone uses a push pull master volume.

                  But anyway, I did figure out how to post pics so the proper material is there for anyone willing to help. I will say, I kind of rushed the wiring a little bit while drinking several beers and watching football at the same time. This is my first amp build but I know that's no excuse. I spent about 4 months making the speaker cabinet and head and I guess I got burnt out so I rushed at the end. Plus my wife was getting ready to divorce me because I was spending too much time with it. You know what I mean.

                  I will say it sounds great if it wasn't for the issue I am having. If I have to, I guess I'll rewire the whole thing again. I guess that's my punishment for rushing it.

                  Channel 2 seems to be working perfectly, Channel 1 has the static past 7 of the volume and channel 1 seems to get very loud, very fast if you look at the video you might notice it.

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                  • #10
                    If you can post some pictures of the inside of the amp it would help. A fresh set of eyes can sometimes spot something you've stared at a hundred times. Don't rewire anything until you've diagnosed the problem, though.

                    I would try to narrow down the problem. I'm assuming the schematic is the same or similar to an original DC30.

                    The first thing is the interaction with CH2. Does pulling the 1st preamp tube for CH1 make the problem go away when playing through CH2?

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                    • #11
                      I see in the inputs of the phase aplitter two capacitors of 100n (0.1uF). Does the DC30 really use that capacitor value?
                      And I also think (I'm not sure) I saw in the video an oscillation at low frequencies (it seemed that it could not stop). If so, itīs very possible that both are related.
                      Last edited by Pedro Vecino; 02-25-2020, 04:50 PM.

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                      • #12
                        The old schematic says .01.

                        Justin
                        "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                        "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                        "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                        Comment

                        • #13
                          I created an open circuit on both FX channels that's only closed when I use a jumper. I also pulled tubes one at a time. Here is the new video. Sorry, I forgot to add that I quadruple checked the wiring again and I did find that the output transformer P2 green and P1 yellow are swapped but I don't see how that would make any difference. Also I am getting 2Rohm between the Channel 2 FX send and ground but maybe that is normal

                          https://m.youtube.com/watch?v=glvv519DClQ&t=21s
                          Last edited by gerry113377; 02-26-2020, 02:08 AM.

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                          • #14
                            So do you think I should change these phase splitter caps to .01uf

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                            • #15
                              The Ceriatone uses .01uf an this makes more sense than 0.1uf. It would do no harm to change them and may be a fix, though I have some reservations because CH2 works OK on its own.

                              Opening the FX loop puts noise - mainly hum - into your amp on either channel. That is normal. Because CH1 volume control affects the problem, I think it lies before this. Removing V1 improves things, though really you need to play the amp on CH2 with V1 removed to get a better idea of whether CH1 volume control still affects CH2 in the same way.

                              You still get some CH1 tone control influence with V1 and/or V2 removed because you have open inputs either to V2 or the tone stack and this is picking up noise which the tone controls act upon.

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