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5f2a (another beginner with the same questions sorry)

Discussion in 'Shock Brother's DIY Amps' started by totterer, May 24, 2018.

  1. totterer

    totterer Tele-Meister

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    Im taking some notes on startup procedure, and Im a little confused on when to use wire to ground testing and when to use wire to wire? I suppose I can figure it out when Im testing, just trying to be careful. I have read through Robrobs instructions a couple times and its not that clear. He mentions measuring heaters wire to wire and high voltage wire to ground.
     
  2. bigguy12321

    bigguy12321 Tele-Meister

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    If you are right handed.. Support chassis so that it won't move. Hook black alligator clip from meter on chassis, use right hand to hold red meter probe.*** LEFT HAND IN BACK POCKET!!!*** (i.e. only one path to ground) this is for all high voltage.

    Left handed you are on your own... (seriously, just reverse hand with probe and hand in back pocket for more stability)

    For heaters. After all sockets are wired and before tubes are installed, alligator clips from meter, black on pin 4/5 of 12ax7 and red on pin 9 then flip on power. Should be 7-ish VAC unloaded.

    a
     
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  3. tubeswell

    tubeswell Friend of Leo's

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    DC voltage for plates, screens, cathodes and High Tension voltage supply nodes is usually measured to ground. Use the VDC setting on your meter and if its a manual meter, set the dial at the scale for which you need to measure the voltage (ones, tens, hundreds)

    AC voltage on the PT's secondary windings (including for the heater winding) is measured between the winding ends (or from each winding end to the winding's centre tap, where there is one). Note that for AC heater supplies, 'the winding ends' = 'between the heater pins' or 'between the lamp terminals' (where you have a 6V lamp). Use the VAC setting on your meter. Same story about meter scale.
     
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  4. totterer

    totterer Tele-Meister

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    Thanks guys, I think I'm ready to proceed. I know this is Shock Brothers amp forum, but I would rather not. (Get shocked) Maybe I can become a brother some other way?
    :D I'll keep you posted on how it turns out
     
  5. totterer

    totterer Tele-Meister

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    IMG_20190411_194049380.jpg
     
  6. totterer

    totterer Tele-Meister

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    IMG_20190411_195840241.jpg
     
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  7. totterer

    totterer Tele-Meister

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    I straightened the grill cloth a little on the top, not perfect, but Im pretty happy with how it looks. Uncle Doug video had some great tips!! I also applied some shellac to the faux tweed. I was worried it wouldn't stick, but it seems fine. Gives a little more vintage look. Thats my homemade cyclone dust collector in the back. My shop is in the basement, so its a necessity!
     
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  8. bigguy12321

    bigguy12321 Tele-Meister

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    Looks Great!!!

    BTW, where is the "faux tweed" from? Looks really nice.

    a
     
  9. totterer

    totterer Tele-Meister

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    IMG_20180418_132120497.jpg
     
  10. totterer

    totterer Tele-Meister

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    IMG_20180418_132027312.jpg
     
  11. totterer

    totterer Tele-Meister

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    Here is a couple pictures to give an Idea how I was lining things up. Not the Fender way, but looks decent.

    The "tweed" is actually vinyl. Its from a Chinese company called Ampmart and thats where I got the chassis and grill cloth from as well (the chassis seems equal to others available). Its backed with cloth, but the design is definitely printed on. Its pretty convincing however and was a cheap way to get a bunch of it. I couldn't stomach the price of "real tweed". So found this stuff, but wasn't really sure what I was gonna get. I figured the learning curve would be way steeper learning to apply this stuff, but it was fairly forgiving. I did use hide glue, definitely the way to go, if you want to remove something, just heat it up with a little water and it will peal off. Its the traditional way and also non toxic. (not for the horses)
     
    Last edited: Apr 12, 2019
  12. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    This may have said already, but for Fender 5f2a voltages, you can use those from the 6G10 -- a 5f2a re-branded as a 'Harvard.'

    Harvard schematic with voltages.jpg
     
  13. totterer

    totterer Tele-Meister

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  14. totterer

    totterer Tele-Meister

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    Okay thats is, now I have something to test this thing on. Too bad I work the next 6 days. :( I guess thats nothing when you consider I started this project over a year ago! Time flys even when you're not having fun... Thanks King fan. I got that, it took me a minute at first to figure out that this is not the other Harvard I have read about.
     
  15. totterer

    totterer Tele-Meister

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    Okay first problem..... I plugged in the 5y3 and limiter etc. and took preliminary voltages and al looks as it should. Turned it off, discharged the capacitors and my tool works. Then came the problem. I tried to plug in the 12ax7 and no dice. It appears one of the sockets on the filament somehow has solder in it, even though I don't see any way it could have flowed down there. There is no visible gap, it none the less appears filled up with solder or defective in some way, Must have wicked in there?? I guess I was so worried about getting solid connections I heated it up too much and it flowed into the socket I. I don't see any way to remedy this other than replacing the socket. Is this common or is there a fix? Maybe get a solder sucker in there somehow??? This socket just seems like a garbage socket anyway:mad:
     
  16. D'tar

    D'tar Friend of Leo's

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    Heat it up and solder wick or suck it out. Less appropriate desperate measure... Heat and tap or blow it out. Enter at your own risk.
     
  17. totterer

    totterer Tele-Meister

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  18. totterer

    totterer Tele-Meister

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    I guess this is pretty much ruined. I tried heating from above while trying to shove solder wick in the bottom, no dice. Finally got desperate and shoved the smallest soldering tip in the socket and could see how much solder was in there when it flowed down and filled up the hole. Ended up completely melting the housing and pushing the entire thing up through the housing as it melted. Didn't really take that much to ruin this thing, seems very flimsy and fragile. Not good. Hopefully they make better sockets than this. What brand do people like?
     
  19. D'tar

    D'tar Friend of Leo's

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  20. totterer

    totterer Tele-Meister

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    It says its made of Micalex will that melt? I was kind of thinking about a ceramic socket. I think the one I just ruined was some kind of plastic. Seems ridiculous to make something like this out of plastic!
     
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