5F1 Kit Build - no sound

Discussion in 'Shock Brother's DIY Amps' started by brackp, Feb 14, 2019.

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  1. jtcnj

    jtcnj Tele-Holic

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    AS above with the popping / scratching; you dont need the signal tracer to get this far.

    You said reversing the OT primaries gave a slight squeal.
    that squeal, when you get it, should be LOUD.

    You will need to switch those back, unless you leave the NFB disconnected.

    Either your power tube is not conducting, but by your voltages it should be, or

    Your OT secondaries and / or output jack wiring is incorrect, shorted or both sides grounded (same same) Or faulty OT.

    Your speaker wire / plug / speaker connections are faulty.

    Sort those and you will get sound - the popping by touching meter leads or tapping grid wire at 6v6.
     
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  2. brackp

    brackp TDPRI Member

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    The power tube is lighting up, and hot to the touch. I think it's ok.

    Here's the jack socket I'm using, I noticed when I jumped the signal and the center pin of the jack I do get some sound (from the volume pot) out of the speaker.

    Does my wiring there look ok to everyone?

    20190215_200936.jpg 20190215_200839.jpg 20190215_200904.jpg 20190215_200854.jpg
     
  3. brackp

    brackp TDPRI Member

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    wait a sec....the middle pin goes to the tip of the jack...which is, I presume, where the green from the output transformer should go too right? And I should rewire the input jacks too...Am I right?
     
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  4. jimgchord

    jimgchord Tele-Afflicted

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    The middle pin is not the tip pin. That is the shorting pin.
     
  5. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    These are weird looking jacks. If I'm looking at the pictures right...and you have the pins facing up like how a pot would look from the rear...

    Left = Ground/casing/shield
    Middle = tip
    Right = shorting tab

    You can confirm with with that unused one in your photos and a multimeter.
     
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  6. brackp

    brackp TDPRI Member

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    Yeah that's what it looks like to me, confirmed with a multimeter too. I've got some work to do so, progress at least!

    20190215_210606.jpg
     
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  7. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    The insulating spacers on those look super flimsy. Once you get it working, add some good ol' Switchcraft jacks to your next order and you'll never have to worry about it again.
     
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  8. Whatizitman

    Whatizitman Friend of Leo's

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    Hmm. I've had some problems with some cheap phono jacks on pedal builds recently. They are finicky and difficult to ground properly. Maybe check to see if the shorting section is bent on the installed jacks?
     
  9. D'tar

    D'tar Friend of Leo's

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    Sweet progress. While things are apart.... Measure those two 100k plate resistors(resistance) for V1. And v1 pin8 to ground(resistance) without the nfb resistor connected to the jack.

    The one plate load acts like a 10k rather than a 100k
     
  10. brackp

    brackp TDPRI Member

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    Success! It's somewhat working now. I was getting no volume until about 10 and from there I get a little bit. I wiggle the speaker cable and get a little bit more so that speaker cable needs attention. I plugged it into my Blues Jr speaker and I start getting some volume around 4-6, still quiet, then from 10-12 I get more volume. It's still very quiet though. Like loud enough to play at 11pm this evening without being worried about bothering people in the room next door quiet.
    Still, great progress! Delighted with it so far, it's a fun challenge, even when you do something as stupid as I managed to do with the Jacks :)
    I'll order some switchcraft Jacks asap.

    Thanks a million everyone, if someone can explain the volume aspect I'd be delighted
     
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  11. D'tar

    D'tar Friend of Leo's

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    See my last post. Can you give new voltages now that we have sound. That v1b is suspicious.
     
  12. King Fan

    King Fan Friend of Leo's

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    What a sad looking little jack; sorry but it needed to be said. Yes, Switchcraft all the way. Sure, even there you can get a shunt prong that's not bent away from the tip prong, but they stay straight and rigid once you adjust them.

    For now, can you bend the shorter, shunting prong so it's further from the tip prong when a plug is in place? That's easier to do (and confirm) when the jack is installed. Nearly-shorted output will vary when you wiggle the cable.
     
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  13. D'tar

    D'tar Friend of Leo's

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    Lol! Not first quality for sure!

    I dont know about Ireland, or the rest of the amp building world, but I know a lot of us are spoiled with the availability of quality parts and pieces. Also, if everyone had a source as quick as Hoffman's shipping Dpt. Parts available will be in your mailbox when the sun comes up in the morning!

    If that were a kit.... Shame on them IMHO. If trying to save a $, well, you get what you pay for.
     
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  14. brackp

    brackp TDPRI Member

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    It was a kit, some of the parts seem pretty decent but those jacks are pretty miserable alright, we've got pretty good availability for electronics parts here in Ireland so I've got 6 new switchcraft jacks on the way.

    I took new voltage readings this morning

    B+1: 328
    B+2: 281
    B+3: 230

    at R7: 74
    at R5: 155

    5Y3
    2/8: 328 (Can't read A/C here but seems to be working - is that normal, guessing cause it's connected to B+ through pin 8)
    4/6: 285

    6V6
    2: 3.2 AC
    3: 316DC
    4: 279DC
    5: 0
    6: x
    7: 3.2 AC
    8: 18v

    12AX7
    1: 150DC
    2: 0
    3: 1.1DC
    4/5: 3.2AC
    6: 72DC
    7: 0
    8: 0
    9: 3.2 DC

    Also noted that I'm no longer reading DC voltage above the coupling caps...not sure why.

    A few things of note, I'm getting wildly different reading from last night on the 12AX7.
    Pin 1 was 181 last night, reading 150 this morning, Pin 6 was 255 last night, only 72 this morning.
    And nothing on Pin 8 at all this morning, was getting 3.5DC here, was that the leaking DC from the cap previously?
     
  15. D'tar

    D'tar Friend of Leo's

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    Normal... The VAC in has been rectified and now is VDC. You should see 5vac heater voltage though or else the tube would not conduct.

    Back to v1 voltages

    I would recommend running the amp as little as possible until v1b is figured out. By the readings v1b triode may be redplating.

    With the amp off and caps drained. Just as corliss suggested earlier. Measure reisistance of the cathode pins(3,8) to ground on v1. However, We need to disconnect the NFB wire to get a proper reading on v1b.

    Also measure resistance of the 2x100k plate resistors. I suspect these are fine but lets rule that out.

    As a precaution, I would re-tension the sockets on V1.
     
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  16. brackp

    brackp TDPRI Member

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    Still reading 2ohms from pin 8 to ground, with the nfb disconnected.

    From pin 8 to the turret between R13 and R6 I'm reading 1.5k

    From pin 8 to the opposite side of R6 I'm reading 2ohms. And from there to ground is 2ohms...

    The 100k resistors are good.

    Forgot to mention, pin 3 is reading 1.5k

    Thoughts?
     
  17. brackp

    brackp TDPRI Member

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    What are the voltages expected here? I would have thought excess voltages would cause redplating no? I thought mine were on the low side

    Ah, it's the current right? Lack of resistance


    Editing again cause I don't want to spam too much, I disconnected the wire to pin 8 and measured from there to the turret, 1.5k. to ground...2ohms. I've got a short to ground under the board don't I?
     
    Last edited: Feb 16, 2019
  18. D'tar

    D'tar Friend of Leo's

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    I suspect you have your cathode lead wired to the wrong turret. Do you have photos of the under the board wiring?
     
  19. D'tar

    D'tar Friend of Leo's

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    Correct
     
  20. D'tar

    D'tar Friend of Leo's

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    You could disconnect p8 wire at the socket and secure it. Then run a temporary jumper to the correct turret. If test ok then make a permenant repair.
     
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