5e3 Mojotone Build - First Time Builder

Discussion in 'Shock Brother's DIY Amps' started by Pick_n_Strum, Nov 9, 2019.

  1. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Yep, don't plan on making that mistake again. Glad you told me your growing pains as well - I would've never even thought about the faceplate scratching if I was drilling holes. Especially in the opposite side.

    I suppose this won't be my last mistake but I'm going to try and minimize them
     
  2. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    I'm not sure what happened to my photos in #19. I copied them in-line here and I'm pretty sure they were JPEG...Let's try this:

    So I've been wiring up slowly but surely - repetitively checking continuity as I go.

    Against your guys' warnings and my better judgement, I did decide to take on the mods as I'm building. This had a few logistical challenges (where to put toggle for negative feedback, where to route shielded wire). So on to the photos:

    Master volume pot - I had to add sheet metal because the former owner of the chassis drilled a huge hole in the standby slot:

    [​IMG]




    SPDT from the outside - for the negative feedback switch:

    [​IMG]



    SPDT from the inside and most of the board - I went with shielded wire for both the SPDT and master volume - some of that will be routed back underneath the board for neatness-sake (I definitely need to work on neatness!):

    [​IMG]



    One really stupid thing I did was drill the master volume hole with the transformer in (I know I know, I've been scolding myself) - I ended up nicking the insulation on one of the red high voltage secondary wires of the PT. I'm so mad at myself. I put 2 layers of heat shrink on it, both layers rated for 600v but it would have been much smarter to just pull the transformer out prior to drilling. Lesson learned:

    [​IMG]



    Please go easy on me :cry:
     
    Last edited: Nov 25, 2019
  3. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Well, I officially have a working 5e3 Deluxe - I absolutely love it. Really really enjoy the mods too - especially the master volume for at-home use. I definitely have a lot to improve on my next build - most notably, the neatness. It's surprisingly quiet - I was expecting to have to deal with some hum.

    All the voltages checked out, except compared to RobRob's cathode bias voltage. My numbers were quite different (both plate voltage and plate resistance) - but when I compared it to the tube dissipation, it looks like I'm running at about 106%. According to the recent Boothill 5e3 thread, it sounds like that is pretty close to normal for these guys...Also, there is no red plating whatsoever. Here are some pics of the wiring and final product (note: I'm going to be tightening that grill cloth in the near future):

    [​IMG]


    [​IMG]


    [​IMG]


    [​IMG]

    [​IMG]


    [​IMG]
     
    Tele Slacker and Tommyd55 like this.
  4. Paul G.

    Paul G. Friend of Leo's

    Posts:
    2,803
    Joined:
    Mar 17, 2003
    Location:
    Rhode Island
    I see you have a switched pot for the master volume. Is there any difference in the hum level when activated? I was worried about sending signal so close to all that AC, so I swapped the on/off switch to the ground hole (marked standby on your chassis) and put the master in the old power hole. Quiet as a mouse.

    mm 5e3.jpg
     
    Pick_n_Strum likes this.
  5. King Fan

    King Fan Friend of Leo's

    Posts:
    4,613
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Good looking build, actually. And you got it working perfectly? That's beautiful right there.

    You're maybe making a few of us OCD guys a little wacky by 'describing' voltages instead of listing them:

    Care to share numbers? :)
     
    Pick_n_Strum likes this.
  6. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Yeah, I just put it through the ringer - there is absolutely no in difference white noise / hum with the master volume engaged. I did use shielded cable and grounded it at the power tube grid leak resistors.
     
    Last edited: Dec 1, 2019
    Paul G. likes this.
  7. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Yeah, it seems to be working correctly - even all the mods.

    So, the voltages I was concerned with were when calculating my bias point. I just redid it this morning. I actually found that I was running pretty close to 100% Here's what I did:

    V3 Plate Voltage: 354.8
    V4 Plate Voltage: 356.1
    OT Center Tap V: 367.8

    Voltage Drop V3: 13 (367.8 - 354.8)
    Voltage Drop V4: 11.7 (367.8 - 356.1)

    CT to V3 Res: 342.8 ohms
    CT to V4 Res: 303.4 ohms

    13 / 342.8 = 37 mA on V3
    11.7/303.4 = 38 mA on V4

    I then measured cathode voltage at 22.4 and subtracted that from each power tube (I did not do this step the other night when I thought I was running at 106% - I simply put in plate voltage - doh!)

    I put the plate to cathode voltage into the tube bias calculator and got 36 mA max plate dissipation - so I'm really right there. Actually my numbers last night were 36 mA on both tubes.

    The part that through me was that in Rob's example, he got voltage drop numbers at 1.3 (both tubes) and resistance at 72 ohms and 80 ohms. My numbers were much larger in both categories which concerned me.

    I can get my other DC and AC numbers up if interested but those voltages were all very near RobRob's posted voltages.
     
    King Fan likes this.
  8. dan40

    dan40 Tele-Afflicted

    Posts:
    1,521
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    Great work and congratulations on a successful build! I was gonna ask if you had measured from plate to cathode when doing your bias calculations but I see that you have already caught that. Enjoy your new amp!
     
    Pick_n_Strum likes this.
  9. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Thank you - I absolutely love it. So, it sounds like my voltage drop and plate resistance is okay? I was just surprised how far off it was from the Rob Rob example.
     
  10. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    I have an unfortunate update on this. I did notice a very small amount of hum today and I believe it's the MV. I literally had my head right next to the amp as the tubes were getting warm and I noticed just a very a light drone (like a tiny bit of 60 cycle hum) without a guitar plugged in. Nothing really changed it. I tried chop sticking the entire circuit, changed some preamp tubes, etc. The absolutely only way to get that drone completely gone was to engage the MV and have it turned low or all the way off. With that said, I'm literally sitting about 3 feet away from my amp with bright volume on 3 and tone on 8 and I can't hear the drone so I'll probably just leave it as is.
     
    dan40 and Paul G. like this.
  11. dan40

    dan40 Tele-Afflicted

    Posts:
    1,521
    Joined:
    Aug 19, 2015
    Location:
    Richmond Va
    You could try moving your grounding point of the MV but if it's that small of a noise, it may be best to leave it as is.
     
    Pick_n_Strum likes this.
  12. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Got you - Yeah, I think for now I'll leave it as is. To put it in perspective, my single coil hum is much much louder. I can't even really tell the amp is making a hum until I engage the MV and hear completely dead silence.
     
    Paul G. likes this.
  13. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Wanted to put some better final pictures up here to close out the thread. Thanks again for everyone's help! The amp is still working great! I've played it everyday since I finished it. I'm already working out my next build - the addiction is real!

    [​IMG]



    [​IMG]
     
    JohnnyCrash and BobSmith like this.
  14. BobSmith

    BobSmith Tele-Meister

    Posts:
    204
    Joined:
    Feb 12, 2018
    Location:
    San Jose,CA
    Looks great. Love the grill
     
    Pick_n_Strum and JohnnyCrash like this.
  15. King Fan

    King Fan Friend of Leo's

    Posts:
    4,613
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Pretty amp. Super build. Nice job!!
     
    Pick_n_Strum likes this.
  16. drneilmb

    drneilmb TDPRI Member

    Age:
    112
    Posts:
    98
    Joined:
    Nov 30, 2019
    Location:
    Decorah, Iowa, USA
    Agreed, that wicker grill is super cool! OP, was that something you had around, or did you buy it just for that purpose?
     
    Pick_n_Strum likes this.
  17. Pick_n_Strum

    Pick_n_Strum TDPRI Member

    Age:
    30
    Posts:
    64
    Joined:
    Sep 28, 2016
    Location:
    Lino Lakes, MN
    Thank you! I had planned it based on other 5e3 deluxes I had looked up images of. Ended up buying it off Ebay - It's a mesa boogie patter (which I didn't find out until after).
     
  18. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted Silver Supporter

    Posts:
    1,977
    Joined:
    Dec 11, 2009
    Location:
    Bloomington, MN
    Very cool!
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.