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Tweed Deluxe Build

Discussion in 'Amp Central Station' started by Munga, Nov 22, 2006.

  1. getbent

    getbent Telefied Silver Supporter

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    Check your grounds... are you grounding to the brass plate or a buss or star to a post?

    since it is running and not blowing fuses.. do the chopstick test.. that should tell you a bunch... my advice... print a layout and wherever you get noises when you tap with the chopstick mark it... heat tha solder joint... and check and recheck in your jacks to make sure you are wiring them correctly.
     
  2. Munga

    Munga TDPRI Member

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    I may have found the problem. I forgot to solder one lead of the jumper from pin 3 to 8 on the first preamp tube.
     
  3. Munga

    Munga TDPRI Member

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    Ok, scratch that. It didn't solve the problem at all.
     
  4. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    1. Double check the tone pot's lugs.

    2. Also double check the solders from the middle lug of the Volume pot to the 1uF cap on the board, as well as the same connection to the Tone pot's #1 lug.

    3a. Check to make sure the cap on the Tone pot's lug #3 is the proper value.
    3b. Make sure the ground connection of this cap is solidly to ground. Those brass plates are often hard to solder onto very well.
     
  5. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    Also the volumes shouldn't interact like you're describing. This leads me to believe the issue is with the Tone pot as well since both Volumes share the pot.

    They interact without jumpering channels, right? How so?

    The 12AX7 is actually two tubes in one envelope. Both halves are triode tubes (three component tubes) in one glass case...

    I believe each Volume pot is driving each triode's plate (pins 1 and 6) individually.

    Pins 3 and 8 are each triode within the 12AX7's cathode. They share the same cathode resistor and bypass cap.
     
  6. Munga

    Munga TDPRI Member

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    I checked all that, with continuity and ohmage tests, and have seen that they all pass. As far as I can tell, the problem lays inbetween the input jacks and the volume pots. The weird thing is, both pots work. :/
     
  7. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    This is for the Tone pot not doing anything, right?

    If not, what is the trouble? I'm sorry, I musta got confused :)
     
  8. Munga

    Munga TDPRI Member

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    Actually, they are acting like how kludge said. I percieved it as a change of volume at first, because of my utter shock the second volume affected the tone.
     
  9. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    His post isn't very specific.

    What exactly is happening?

    This should be a quick and easy fix either way...

    One other thing - check to make sure you're wiring to the proper outside lugs and not reversed on one or more pots. This is easy to accidentally do.
     
  10. Munga

    Munga TDPRI Member

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    Well, right now I am trying to solve the problem of the 2 normal channel jacks not working.
     
  11. DrewB

    DrewB Tele-Afflicted

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    Maybe these'll help...

    [​IMG][/IMG]

    [​IMG][/IMG]
     
  12. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    OK, this helps...

    Hmm, let's see.

    Failing to jumper pins 3 and 8 on the first preamp tube would have messed with pin 3's half of the tube. That would've taken out one channel. Double check this again.

    You've probably already checked the jack wiring. Hmm...

    Make sure both jacks are going to 68k resistors. I accidentally wired a 100 ohm resistor instead of a 100k ohm resistor, the meter kept showing "100" so I kept missing it by forgeting to look for th "k".

    Hmm..

    Check the first preamp tube's plates. Especially the underboard jumpers! Actually they're both tied to the one junction at those 100k resistors, so this would take out both channels if it was missing that jumper. WAIT A MINUTE, make sure they're BOTH 100k resistors and not simply 100 ohm here!

    Also check the second 12AX7 tube's pin #2...

    Let's see, what else can I think of... let me go check out the schematic again... BRB.
     
  13. Munga

    Munga TDPRI Member

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    100k, 100k. Check.
    Its reading 33.5k across both 68ks, but that is fine, I am pretty sure.

    Every thing I can possibly check has the proper continuity and resistance! AGHHHH!!! :cry:
     
  14. zook

    zook Friend of Leo's

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    Check the voltages on the preamp tubes. On V1 what are the plate voltages (pins 1,6) and cathode voltages? (Pins 3, 8) Same with V2.

    On 1 and 2 of V! you shouyld have somewhere between 100V and 200V(I'm guessing but it's good to know) also on the cathodes, somewhere between, 0.5Volts and 2 Volts.

    On the Phase inverter triode it will be about 40Volts on the cathode.

    Winnie

    Winnie
     
  15. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    I don't think so. If they were tied together at both ends, yes, but... hmm, double check them jacks, but maybe I'm wrong...


    It can get frustrating, but we can figure this out. Don't get discouraged (I remember how bummed I got on my first few troubled builds, and it sucks bad).

    We just need to follow this logically... from the symptom.

    Also, I had checked, double checked, triple checked, quadruple checked... only to realized I still missed something.

    Look long and hard at the jack wiring, those triple lug input jacks are easy to "see" as wired right, but still end up being wrong...

    I'm grabbing some coffee... we'll figure this out, BRB.
     
  16. Munga

    Munga TDPRI Member

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    Plate voltages on V1 are showing about 170v each. 1.4v on 3, about 1.7v on 8 for v1. For V2, 168v for pin 1 and 214v for pin 6. 1.5v on pin 3 and 52v on pin 8.
     
  17. Munga

    Munga TDPRI Member

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    Well, the other set of jacks also read 33.5k right there, so that can't be the problem, can it?
     
  18. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    It is a tweed Deluxe afterall... there aint much here to look for. Especially since we know it's only on the ONE channel.

    Quadruple check the inputs, connection to the board, board to tube socket, entire tube socket wiring, and pots.

    Follow the track from input to pot and tube.

    I often find it's something so obvious or simple I overlook it many many times before seeing it right in front of my face.

    I'm trying to stop drinking for a few weeks, but this is getting hard... I can't focus on jack squat.
     
  19. Munga

    Munga TDPRI Member

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    I had a tech over AIM help me figure out that every connection after the preamp tube is fine, so it has to be somewhere between the tube and the jacks. Soooo, tonight or tommorow, I decided I am just gonna rewire everything within that space. I hope that helps!
     
  20. ajmikula

    ajmikula TDPRI Member

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    Good luck! Hopefully we'll be able to hear some clips sometime! ;)
     
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