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First Build - Rob Robinette Micro Champ

Discussion in 'Shock Brother's DIY Amps' started by SJK45, Aug 14, 2020.

  1. andrewRneumann

    andrewRneumann Tele-Holic

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    Just checking sanity here. You have a 240vac light and not a 6.3vac light, correct?
    If 240vac, then yes, you have to jumper from the switch. One end to each terminal where the brown PT wires will connect. That is a sweet transformer by the way!
     
  2. SJK45

    SJK45 TDPRI Member

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    Yes - at the moment the light is 6.3v but I've ordered a 240 one. I suppose I could, alternatively, take the 6.3 out from the transformer and put that straight to the light? and from their to the heater wiring?
     
  3. SJK45

    SJK45 TDPRI Member

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    Hi Rob,

    I am a bit confused - does that mean that the headphone resistor is on the speaker Jack?

    Spencer
     
  4. andrewRneumann

    andrewRneumann Tele-Holic

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    Yeah, you understand what’s going on. Using the 6.3v winding is the traditional way it’s done. But... straight from the mains actually makes more sense to my way of thinking. It’s really up to you! Just make sure to use the right value for the bulb.
     
  5. D'tar

    D'tar Friend of Leo's

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    Yes, the resistor is wired between the shunt and ground on the speaker jack, the jack you have wired now is the tip-ring-sleeve jack and needs replaced with the Tip-shunt-ground jack.

    I like the recommendation to use a 1/8 trs headphone jack so there is no confusion of which jack is which.
     
  6. SJK45

    SJK45 TDPRI Member

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    Actually I think that I see from the schematic (and your instructions) that the headphone resistor is on the speaker jack. Sorry should go back to that more often!
     
  7. SJK45

    SJK45 TDPRI Member

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    Thanks for replying. I see that I've used a TRS jack rather than a TS jack but it doesn't matter this way around does it? Won't the TRS work fine as wired?

    S
     
  8. D'tar

    D'tar Friend of Leo's

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    On the trs jack... t=left headphone speaker, r=right headphone speaker, s=sleave/ground. The 10 ohm resistor needs to be between shunt and ground of the shorting mono jack to safely load the OT when the speaker jack is unplugged and using the headphone jack. Creatively you may get it to work but I would recommend sticking to the schematic and layout as designed to reduce future issues.

    7FAC53A9-4693-4DB8-90C7-C225A034D1CF.jpeg
     
  9. SJK45

    SJK45 TDPRI Member

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  10. SJK45

    SJK45 TDPRI Member

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    Thanks - I’ll change those over. Not sure I have a TS socket so I’ll order one.
     
  11. SJK45

    SJK45 TDPRI Member

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    9D9C89F2-AE43-4C5B-872B-6C36135ED4FD.jpeg 7AF8A0C8-72A4-4EF7-A348-3AA3D71C028A.jpeg These are my two valve wirings. I’m not at all confident that I’ve got this right. It was pretty fiddly.

    I’m not sure I’ve got the orange wire for the power tube right. It comes from the 470k grid stopper.

    Also I’ve wired it so the 6.3v green just stops at the power tube.

    The soldering is bad enough when I've not zoomed in! Interesting that I've spotted some soldering mistakes now that I've zoomed in though.
     
    Last edited: Sep 13, 2020
  12. SJK45

    SJK45 TDPRI Member

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    4601C177-0E64-487B-8213-356AFDEE91EE.jpeg It’s not a great layout - next time I’ll drill my own holes!

    I mostly just need to connect the transformers now. Have to say I’m feeling a little lost though.
     
  13. D'tar

    D'tar Friend of Leo's

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    If you want "only" a "speaker out" or "only" a headphone jack to get up and going, we can help wire that trs jack. The way it is now the signal appears to go to the ring terminal which is no good for a speaker mono plug.
     
  14. D'tar

    D'tar Friend of Leo's

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    Please post the specs for your PT.

    I think we need to look at your power switch.... Your switch is not proper to switch both line and neutral.

    20200913_125706.jpg
     
  15. SJK45

    SJK45 TDPRI Member

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  16. D'tar

    D'tar Friend of Leo's

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    With THAT switch remove the neutral and connect to the zero lead to the transformer and connect the 240 lead to the switch where you removed the neutral.
     
    Last edited: Sep 13, 2020
    andrewRneumann and Paul-T like this.
  17. SJK45

    SJK45 TDPRI Member

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    I have the eight leads coming out of the transformer in two bunches of four. One bunch is coloured as in the right side of the diagram (Blue, grey, purple and brown). So I have a Brown 0v and a grey 0v.

    I don’t understand the connection You make between the 0 and the 120v? If I connect the blue 240v to where I put the neutral and then attach the neutral to the grey wire where do the other two (purple and brown) come in?
     
  18. andrewRneumann

    andrewRneumann Tele-Holic

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    Dang just having the primaries on the right and the secondaries on the left in the wiring diagram was enough to throw me all off when I looked at it.
     
    D'tar likes this.
  19. D'tar

    D'tar Friend of Leo's

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    Ok, I edited my post to reflect what you are saying. If your voltages are 50% of expected then you will need to adjust

    Edit my edit. Lol

    Youneed to connect the grey and purple together for 240
    Screenshot_20200913-141634_Drive.jpg
     
  20. D'tar

    D'tar Friend of Leo's

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    20200913_134408.jpg
     
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