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This Little Amp Is Trying to Kill Me and My Girlfriend

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

  1. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Ha!
    I ain't mad.
    And the issue was indeed, solved - by many.
    Nothing wrong with the amp - except that it's ugly, poorly built, hazardous, incompetent, and probably immoral!
     
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  2. Asmith

    Asmith Friend of Leo's

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    I think everyone who's picked up a soldering iron at some point have made some less than perfect work along the way. Also I don't know how to make a point to point look anything less than a fire hazard. This is mine

    Screenshot_20200525-014913.png
     
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  3. trev333

    trev333 Telefied Ad Free Member

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    I do guitar/pedal electronics ok ,but I don't mess with live 240V stuff...

    once bitten, twice shy....

    My Dad was an amp geek who built/repaired tube gear in a workshop under our house. I spent a lot of time as a kid sitting on a high stool watching him work...

    The first lesson he taught me about amps when you pull a chassis out to look at is..make sure the earth from the power cable is well grounded... before you ever plug it in... then look for burnt bits/wires/parts, etc... I was too young to get the trouble shooting with a meter/voltages part...

    about as far as I go.... I have a friend who is a good amp tech, I defer to his experience there....

    having had a few good boots from 240V through messing around in the past and other currents from my work welding... I don't want anymore... the next one could be the last...;)

    Plus I live alone.... another reason not to mess with electricity, no backup...:)
     
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  4. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Wow!
    What is it?
    The right half looks like a fishing tackle box.
    Awesomeness!
     
  5. Asmith

    Asmith Friend of Leo's

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    It's a micro amp with a 12au7 output section. The rest is my own design but I copied the eq section from some other amps.

    The enclosure is just a bit bigger than an EHX deluxe memory man.
     
  6. Timjag

    Timjag TDPRI Member

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    Was it like this ?

     
  7. jhaberly

    jhaberly TDPRI Member

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    I don't think GoldDeluxe5E3 was trying to be rude. Your original post, second sentence, "Last night, I plugged it into an ungrounded, three prong outlet in my garage" may have contributed to the confusion.

    I have this issue with a metal lathe where I get shocked if I stand in bare feet on the concrete floor and touch it. This is because the machine is not connected to the ground at the outlet. Does the ground at the point where the cord is plugged into the amp actually make it to the ground (earth ground, not not the neutral)? 55 volts to ground from the grid circuit of v1a seems like the ground circuit is floating. I know sometimes when connecting the star topology of ground it's easy to miss connecting it them. Just thinking out loud here.

    Interested in hearing what you find! Cheers!
     
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  8. jhaberly

    jhaberly TDPRI Member

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    At this point that sounds like the issue to me as well.
     
  9. lavrgs

    lavrgs TDPRI Member

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    No one has mentioned using a dim bulb tester. It may provide some further insight to determine what/if something is shorting. A DBT is a cheap and handy tool to have. There are many design out there for reference...>Rob Robinette's site comes to mind
     
  10. ClashCityTele

    ClashCityTele Tele-Afflicted

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    You can buy amps you know!

    Much safer.
     
  11. bbetancourt

    bbetancourt TDPRI Member

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    SWEET-TALK-ON...
    Imagine, just imagine, this to be true.
    Wouldn't it be a lot easier to accept reality as it is and try to look at the problem from the ground up? Instead of barely brushing the surface just not to hurt anyones feelings?

    SWEET-TALK-OFF

    Brushing the surface of this amp can not only hurt your feelings but kill your body - the latter, being a permamanent condition, has to be taken serious.

    Lets face it, this IS a botched build. Looking at the photos gives everyone with just a spoonfull of EE-experience the creeps. I see so many dangerous spots in any of those pictures that I don't know where to start. And If you take a look a the postings of the fist two pages everyone points out a different problem (and not always too friendly).

    You didn't dare to take on the lot, you just pick at the one who summed it up.

    bye/bb
     
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  12. luwiluwi

    luwiluwi NEW MEMBER!

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    Doesn’t look like you’re grounded!
     
  13. bbetancourt

    bbetancourt TDPRI Member

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    ... and others got electrocuted on stage.
     
  14. sds1

    sds1 Tele-Afflicted

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    Teach us!! I think OP has already taken care of his earth reference situation. What else did you have to add?

    You can take as much time as you need. Maybe a numbered list with pictures of all the problems you see.

    Kindly use EE terms as much as possible. "Botched", "the creeps", for example, these are highly subjective, non-technical terms and aren't too helpful or even a little interesting. You have a mostly technical audience here.
     
    Last edited: May 27, 2020
  15. Bakersfield Boy

    Bakersfield Boy TDPRI Member

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    I suggest that you take it to a competent amp tech, and have it made right. You shouldn't continue to work on it since you are apparently not qualified to do so. Pretend that it's a nuclear reactor, and that you don't have an adequate background in physics.
     
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  16. Cruisin Home

    Cruisin Home Tele-Meister

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    Been super busy and just got around to reading this thread. Wow, lot of poop flying around, and very little good advice to help the OP find//fix his problem. Let me give you some electrical engineering advice from a degreed old timer. i work around high voltage 120,000 volts everyday for last 25 years and am still alive so that should say something.

    1) You have a certain amount of leakage current from any circuit. All circuits leak to some degree. for us designers, particulalry of medical equipment, the leakage requirements are very low and sometimes expensive to meet. So to repeat, all circuits have leakage.

    2) now that I know rule 1. How to be safe? Old days (2 prong) leakage could find it's way thru you to ground. Most of the time now so dangerous. A dry human standing on a very dry surface or carpet can be 10's of Kohms. But stand on wet concrete, tile, etc as found in garage, pool area, bath, kitchen, your resistance goes way down(10's of ohms). In actuality 100mA of current can kill you. So society started to adopt two additional safety protections. first being your third prong. Safety ground. normally a low guage wire kept bare and connected to all conductive parts of a chassis, thought being that if current leaks to chassis that it will find an easier way down this wire than thru you. current is lazy, it takes path of least resistance. Ahhh but small current may not be enough to trip breaker, but if your resistance is low (wet, sweaty, bare feet, concrete floor, pool deck, ...) than this current can be enough to kill you. So along comes protection device #2 GFCI. I wont go into detail here how it works but quick explanation is it has a way to "sense" this leakage current and trip open. It does not need a ground to operate, but is supposed to be labeled with sticker (everyone throws this away). Word of caution, GFCI's can fail. they dont have infinite life. there is a test button. should be tested once in awhile. These two safety concepts have saved a lot of harm. Particularly as society evolved with a lot more electric appliances/devices popping up even in wet places like the bathroom, garage, kitchen., pool area...

    I agree with the folks here that you modify your wiring to realize these simple but effective safety concepts. That includes adding ground inside your amp and 3 prong cord. All metal in your chassis should be grounded to this prong.

    3) Now what is cause of your leakage? You seem to still have a pretty leaky circuit. First look at your PT, input wiring, but next look at your capacitor cans. They are notorious for leaking. How do I do this? unsolder your PT secondary, do you still leak? if no add that back in and progressively go down the circuit with only the front end that you've cleared connected. You should find this leakage contributor in short order. it could likely improve the sound of your amp as well.

    Lastly you mention garage. Garage was made for guitar!!! But if it is detached from house and long distance, the proper thing to do is drive another ground rod. again path of least resistance. I moved to a new house 8 years ago and had a detached pool house. kids said they were feeling a tingling in the shower, like a shock. i measured 9voltsAC on the shower fixture to ground. Drove a ground rod....... gone! Drove a second one for extra measure.


    Good luck. As for ugly...beauty in the eye of the beholder. some these old tube devices can get a little rat nested. But ugly girls need love too! just clean up the safety issues, particularly bare wires, etc. It's all about the Tone!!

    PS: (Hey Hal, send pic of electric girlfriend! haha)
    PSS: I'm sure i talked over the heads of some people but not deep enough for others. purpose here was to simplify some basic safety for those without engineering degree and to help the OP find his leaky culprit. please keep your flamethrowers on standby!
     
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  17. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Try reading the thread.
     
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  18. ArcticWhite

    ArcticWhite Tele-Afflicted

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    You could learn to read through before commenting you know!
    Just a thought..
     
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  19. Asmith

    Asmith Friend of Leo's

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    Everyone!

    His amp isn't causing the issue it's the

    The circuit has no reference to 0V so it's drifting off to 50 odd volts, nothing unusual.

    The OP built the amp so don't tell the guy that he doesn't understand how it works and that he needs a tech to fix it.

     
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  20. ArcticWhite

    ArcticWhite Tele-Afflicted

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    Try reading the thread.
    And maybe look at the Pic where I showed the ground.
     
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