MC10 Power Supply Layout

Discussion in 'Shock Brother's DIY Amps' started by andrewRneumann, May 22, 2020.

  1. andrewRneumann

    andrewRneumann TDPRI Member

    Posts:
    51
    Joined:
    Mar 22, 2020
    Location:
    Cincinnati, OH, USA
    I got my first order from Mouser and made some progress on laying out the MC10’s power supply. The power transformer holes were drilled first. Then came the IEC mains cable. I like the IEC connectors because they are so easy to disconnect when testing. I don’t have to disconnect at the wall/surge protector—just pull the connector out at the chassis.

    First step was to create a CAD file with the cutout dimensions I needed for the connector. I use LibreCAD because it’s free. I taped the layout right onto the chassis.


    Then I used a spring loaded punch and scriber to transfer the layout to the metal.


    Finally, drilled the holes (mounting screws are #4) and sawed out the shape. I used a hacksaw handle with a carbide grit rod saw to do the cutting. If you go slow you can be pretty accurate, but if you want it nice it’s best to cut inside line a little and clean it up with filing.


    I’ve been using DIYLC to create circuit board layouts, but I haven’t really been able to go all in and do the entire layout on it. It’s still a little frustrating to use. So, basically I’ve been laying it out as I go, trying to think ahead about where all the wires will end up. Here’s what I ended up with for the power supply.


    It’s a solid state rectifier and I wanted to go ahead and put in fuses for all sides of the PT. The board will hold the HT fuses, diodes, heater voltage droppers (if necessary), standby switch circuitry (I’m following Merlin’s design with a shunted standby that doesn’t completely cut HT) and a fancy LED light (two LED’s, one red and one green, in reverse parallel) to light up the inside of the head shell. I went with 2 reservoir capacitors because 1 just got to be too big. Next time I will consider externally mounted reservoir capacitors because there’s a lot more space outside than in. This design leaves me enough space for about a 10” main board. The more space the better.


    One of the mistakes I made was mounting the panel light directly above one of the screws for the PT. These are the type of mistakes I feel like I have to make once on everything before I learn. argh. It’s a matter of being able to think in 3D and plan ahead. Maybe I’ll move it and cover the hole with a fancy panel cover.

    I’ll be laying out the valve sockets, speaker jack and impedance selector next. Wish me luck and stay tuned! And as always thanks to everyone on the forum who chimes in with answers and ideas.
     
  2. RollingBender

    RollingBender Tele-Afflicted

    Posts:
    1,190
    Joined:
    May 14, 2011
    Location:
    SW Minnesota
    Good luck!

    The hole for your IEC socket looks real good. I use a CNC mill but to each their own.
     
  3. andrewRneumann

    andrewRneumann TDPRI Member

    Posts:
    51
    Joined:
    Mar 22, 2020
    Location:
    Cincinnati, OH, USA
    some day... good fortune will shine upon me and a small CNC will just appear in my shop. Then I would have to get organized and know what I was going to do before I did it.
     
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