5e3 build project-need some help pls

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by IBTom, Aug 26, 2008.

  1. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    I've just completed a 5E3 kit. The kit is from Triode. It's my first build and I'm definately not a tech, by any means.

    All initial tests were good, no smoke, no blown fuse, all tubes lit up nicely, very light hum. I gave it a solid 5+ minutes warm up time and tried out my guitar. No sound. I did some poking around with a bright light and magnifying glass and id'd a wire on one of the 6v6s had broke. I soldered it back on, still no sound.

    I'm not sure where to begin in trouble shooting this. I've traced every wire from turret to final point to ensure I've matched the schematic. I've tested resistors on the board, and they all test to, or very close to thier intended value. I haven't began to test actual voltages yet, since my thoughts are that if voltages were not up to par, there would be other problems noted.

    Any suggestions?

    Thanks,
    Tom
     
  2. ked

    ked Supporting Member

    Messages:
    897
    Joined:
    May 18, 2006
    The first thing I would do is check voltages to make sure you at least have voltage where it is should be. Check you input wiring, make sure it is correct and not grounding out the signal. Look at the solder joints, reflow anything that seems iffy. Make sure your tubes and speaker are good. You said you tested all the resistors so I assume they are correct and in the right location. Also, check the output jack, make sure it is wired correctly and grounded. If you touch the grid of V1 with a probe you should get a pop through the speaker. HTH.

    Ken
     
  3. hasserl

    hasserl Member

    Messages:
    4,734
    Joined:
    Oct 24, 2004
    Location:
    So Cal
    Yeah, make sure the speaker jack is wired correctly, as well as the speaker you're running it out to. I would do that first, before you spend a lot of time running the amp troubleshooting it with no load applied, if it is a mis-wired output. If you're certain all is right there, than start the voltage checks. If all voltages look correct I would follow the signal path looking for where you loose it at. You can start at the input jack and follow it through the amp, checking all connections, or start at the output tubes and work your way backward. As you probe the connections/components in the signal path there should be static noise out of the speaker each time you touch a connection. This is where a signal generator comes in so handy, inject a signal into the front and trace it through the amp step by step looking for the source of trouble.

    If you have no signal generator and scope, you can make some cheap troubleshooting tools with info listed here: http://www.el34world.com/Hoffman/tools.htm BEfore I got a signal generator and scope I fixed a lot of amps just getting creative about how you go about it. Think it through, step by step; take your time and don't panic. When I'm having trouble with a particular project I find it helpful to just get away from it for awhile and stop thinking about it, then when I come back to it later often times I find the culprit right away. Funny how many times that happens.
     
  4. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    Thanks for the tips guys. I'm a mechanic by trade so trouble shooting for me typically takes a methodical approach, just not sure where to start applying my efforts in this new realm. Venturing into the world of electronics is my attempt to demystify some of that "magic" and get a cool sounding amp that I built myself. I'll press on with your help and let you know what I find out.

    I'm going to ask a question that will seem real simple and perhaps stupid to some, but here it goes:

    Since you guys mentioned checking my speaker jacks to ensure they're wired correctly...... My diagram indicates one point on the output jack as a G and the other as a T. In my mind, the G is the ground and the T is the tang.

    The input jacks have a G, T and an S. Applying my logic above, I can , or think I can, figure out the S position.

    Am I correct in my assumptions? If not, that could explain my entire problem.

    Tom
     
  5. hasserl

    hasserl Member

    Messages:
    4,734
    Joined:
    Oct 24, 2004
    Location:
    So Cal
    Sounds right to me, but typically I see these labeled as Sleeve and Tip, the S should be for Switch. Doesn't your output jack have the switch? It doesn't have to to function, but Fender's usually do, the switch being connected to ground so that if nothing is plugged in the circuit is completed to ground, which is preferable to being open.
     
  6. drgonzoguitar

    drgonzoguitar Member

    Messages:
    4,710
    Joined:
    Aug 23, 2007
    Location:
    Twin Cities

    G = Ground
    T = Tip (of the jack)
    S = Sleeve

    It sounds like when you insert a 1/4" male jack, it should break the short between the sleeve and tip. Once this is opened, your input should work. In this picture "Ring" and "sleeve" are interchangeable terms.
    [​IMG]

    The "half-split" method of troubleshooting works for electronics too!


    Take a few pics and post them on the jack if this doesnt help.
     
  7. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    Improvement, however so slight still constitutes progress, right? So what I"m understanding based on all your imput is that per drgonzo's pic, the NC position is a normally closed switch. I examined my input jacks and found that I had wired my ground to the switch and then the switch to the next inputs switch, rather than ground. I de-soldered all four inputs and re-ran them and attempted a test. My achieved results are I now can hear crackling from the speaker when I slide the cord tip into the jack. Didn't have this before. I get a very slight click when I toggle my pup selector switch. My hum is slightly louder than before, though still low. It does increase though when I turn the tone control up to 10.

    Tomorrow night I'll begin reading out the tubes, unless you have any more suggestions.

    Thanks guys!

    Tom
     
  8. phsyconoodler

    phsyconoodler Member

    Messages:
    4,351
    Joined:
    Jul 11, 2005
    Location:
    calgary canada
    If you made that mistake on the output jack,you made it on the input jacks too.
     
  9. sdgvintage

    sdgvintage Member

    Messages:
    345
    Joined:
    Jan 27, 2005
    Location:
    Bristow, VA
    Send me some pics, I help people troubleshoot their 5e3 kits all the time.
    Get my email from my website.
     
  10. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    My amp is rockin! :RoCkInThanks for the help guys! I started checking continuity in each lead and found what was supposed to be an input to preamp V1 point 7 was actually soldered to the output point on the back of the board. Yep, I reversed them while building.

    Amp sounds good. Hum is a little louder now than I'd like and there is a high pitched squeal when any of the controls are turned past 9. When I hit 10 the amp goes silent. Any thoughts on this one?

    I'll play with it a bit, then re-run some of the leads to clean it up a bit and tighten up the twists to see if I can reduce the hum.

    My first amp build! There's certain to be more in the future.

    Tom
     
  11. Trout

    Trout Member

    Messages:
    7,576
    Joined:
    Jun 23, 2006
    Location:
    Illinois/Far West Burbia
    That is commonly associated with reversed primarly leads on the output transformer, try flipping them.
     
  12. phsyconoodler

    phsyconoodler Member

    Messages:
    4,351
    Joined:
    Jul 11, 2005
    Location:
    calgary canada
    No.An amp with no negative feedback doesn't care where the leads are.
    You still have some grounding issues.
     
  13. Trout

    Trout Member

    Messages:
    7,576
    Joined:
    Jun 23, 2006
    Location:
    Illinois/Far West Burbia
    Actually,,

    I have on several occasions had that problem come across my bench. High frequency oscillation caused by reversed primary. In fact, I have seen it happen on a couple SE amps as well.
    And yes they were non-negative feedback amps.
    It is generally a result of poor quality transformer inductance issues.

    One unit I worked on that comes to mind instantly was a 5E3 that used the same OT from Triode Electronics.
    I suspect it was due to the fact that the color coded wires were reversed internally. Simply reversing the blue and brown wires cured it of squeel. Also, when it was wired wrong, the amp would go into cutoff when the knobs were above 9.


    The no negative feedback thing would apply if the negative secondary lead was lifted.

    edit, by his description I do agree he also has a grounding scheme issue as well.
     
  14. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    I've scrubbed through the entire unit. Re-ran my wires to the preamp tubes to clean it up a bit and ensure that I didn't have any obvious areas for the hum to be generated from. Also relocated my power supply cord to get it out of the chassis immediately and away from the rest of the wires.

    No change except the hum is now louder. I'm not finding any areas where there are ground issues.

    I tried the reversing of the brown and blue leads. Bingo. Squeal stopped. Loud hum remained. I can run the volume all the way to 10 now, except that my tone control doesn't work. When I dial it above 2, the amp quiets. Hit 5 and it begins to break and crackle, and that's without playing a chord.

    You guys have been a huge help. Any more thoughts?

    Tom
     
  15. Trout

    Trout Member

    Messages:
    7,576
    Joined:
    Jun 23, 2006
    Location:
    Illinois/Far West Burbia

    Hey Tom, Glad we cured the Squeel,

    Is there any possibility you can post a few pictures? Generally on a 5E3 build a couple photos and the guys here can spot the problem fairly easy.
     
  16. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    After looking at some other wiring jobs online, I see where I'll need to unwind and re-run that mess coming out of the power transformer and the two green lines from the pilot to the filaments will need to be twisted up good too.

    What else can you recommend based on the loss of tone mentioned in my last post?
    I couldn't get the photo's to post directly into the reply, so here's links to them in photobucket.

    http://i406.photobucket.com/albums/pp145/tandt99/DSC_0005_edited-1.jpg
    http://i406.photobucket.com/albums/pp145/tandt99/DSC_0006_edited-1.jpg
    http://i406.photobucket.com/albums/pp145/tandt99/DSC_0008_edited-1.jpg

    Tom
     
  17. tybone

    tybone Member

    Messages:
    1,079
    Joined:
    Oct 3, 2004
    Location:
    Ontario
    You might want to feed your information back to the triode folks for future reference.
     
  18. IBTom

    IBTom Member

    Messages:
    207
    Joined:
    Jul 11, 2008
    Location:
    Hilliard, Florida
    My two sets of 68k resistors on the turret board, input side, after the jacks and feeding to the V1 preamp tube positions 2 and 7 are both reading 34-35k. All other resisters read what they should. The color codes are correct. Could this be part of my problem??

    Thanks,
    Tom
     
  19. hasserl

    hasserl Member

    Messages:
    4,734
    Joined:
    Oct 24, 2004
    Location:
    So Cal
    Did you use the brass grounding plate for your grounds?

    Does your power transformer have a center tap for the filament circuit? How is it grounded?
     
  20. phsyconoodler

    phsyconoodler Member

    Messages:
    4,351
    Joined:
    Jul 11, 2005
    Location:
    calgary canada
    No.When two 68k resistors are in parallel like that they read half the resistance.That reading is normal.
    I can't tell by the pictures if you have a grounded heater centre tap or a pair of 100 ohm resistors.
    I find the biggest area of grounding that causes 5E3 problems is at the filter caps.The original wiring layout is correct and guys often not do it that way for convienience.Well it ain't convienient if it hums.
    Your filament wires need to be in sync with each other too.Pin 2 to pin 2,pin 7 to pin 7 on the power tubes and the same on the preamp tubes.Pins 4 & 5 to the same on the next tube.
    Also running wires so they lay on the chassis is better than up in the air,except for heater wires.They can be either way.
    The input jack wiring is the most confusing thing about 5E3's and if they are wrong the amp hums or may not even work.
    Go to www.hoffmanamps.com and look in his libray of information on how to wire up hi/lo jacks.
    And finally,cheap jacks go a long way to making problems.Use switchcraft only if you want good performance.Weber of offshore stuff is just plain useless.
    In the second picture I see a green wire with a white stripe.Is that grounded?
     

Share This Page