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Millett "Starving Student" hybrid amp

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  1. sam_cat
    Quote:

    Originally Posted by Lil' Knight /img/forum/go_quote.gif
    Did you find out the correct size of the allen?



    Yup... But I have a nicely organised set of about 200 allen keys.. Didnt note what size it was though.

    Sam
     
  2. Lil' Knight
    Quote:

    Originally Posted by the_equalizer /img/forum/go_quote.gif
    I'm pretty sure it's the one labeled 3''/32 in my set.

    cheers!




    Is that 3"/32 or 3/32"? 3/32" is pretty small, I think.
     
  3. Narwhalius
    Quote:

    Originally Posted by tomb /img/forum/go_quote.gif
    From what I read on your last post, I'm not sure you were testing anything. No, there isn't a list of voltages for certain points on the PCB. Quite frankly, the PCB doesn't rise to the level of complication where that might be required.

    Your best bet is to provide us with some pics. Unless you've blown the tube out on that side, you've got a wire loose somewhere - bad terminal block connection, mixed up ground/signal connection, etc. Since you fail to recognize it yourself (not unusual for most folk, else they wouldn't ask for help[​IMG] ), the best bet is to provide a pic or two and see if someone else can spot the issue.[​IMG][​IMG]




    Alright. I'll try to get some pics but I can't guarantee they'll be super quality. The camera I have isn't the best for that. Where should I take pics of? Also, last night I was experimenting with the volume knob. While the amp was turned on and no music was playing I turned the volume knob up almost all the way. At a certain point like 95% of the way to the max the left speaker would "click" on, litereally I could hear a click and then it would turn on, and I could hear static in both ears then. Whilist up to that point I couldn't hear anything out of the left ear.
     
  4. the_equalizer
    Quote:

    Originally Posted by Lil' Knight /img/forum/go_quote.gif
    Is that 3"/32 or 3/32"? 3/32" is pretty small, I think.



    There, third one from the right (80% sure that's the one)... but it could be the second one from the right... [​IMG]

    [​IMG]
     
  5. Lil' Knight
    Ohh, ok. Thanks!
     
  6. tomb
    Quote:

    Originally Posted by Narwhalius /img/forum/go_quote.gif
    Alright. I'll try to get some pics but I can't guarantee they'll be super quality. The camera I have isn't the best for that. Where should I take pics of? Also, last night I was experimenting with the volume knob. While the amp was turned on and no music was playing I turned the volume knob up almost all the way. At a certain point like 95% of the way to the max the left speaker would "click" on, litereally I could hear a click and then it would turn on, and I could hear static in both ears then. Whilist up to that point I couldn't hear anything out of the left ear.



    This almost confirms that you've got bad solder connections at the pot, and that perhaps casing and uncasing it put enough stress on it to loosen some connections. The clicking is where the circuit makes contact through the volume pot when it's shorted (turned all the way up). The signal is partially diverted to ground before that, and as the volume control is adjusted upward, less and less signal is sent to ground. However, if the ground connection is not there, then the circuit is broken until the full-shorting connection is made, hence - no sound.
     
  7. Entropy1
    I've finally found the source of the volume difference. I installed the tube sockets upside down originally (Yeah, I know that's pretty bad) Anyways, I didn't have a solder sucker or anything at the time so I had to remove the sockets one pin at a time. Once I had done this, I had to drill out the remaining solder any I must have messed up the connection to the PCB then. Between pin 1 and 2 and C4 there was no continuity meaning the tube wasn't getting power from the MOSFET. I know it's a bit sketchy, but I ended up just running a piece of wire there to make the connection.

    The remaining problem is that when I turn the volume low, there is still a bit of audio in the right channel. This volume is proportional only to the volume of the source and not the pot meaning I must have a bridge somewhere. I will keep up the search for this.

    With the volume up on the amp, both channels equilize. My first impressions ( <30 minutes runtime on the amp ) are very good despite how bad I think my mp3 player's DAC sounds. There are still some pops and crackles here and there but that is probably due to the break in and the amp not being inside the case yet. The leak into the right channel is actually from the left input as I've just found out so I will be looking around for the cause of that. Anyways, I'm making progress and if I do okay getting everything working, maybe I'll be up for a gamma 2[​IMG]
     
  8. Narwhalius
    Quote:

    Originally Posted by tomb /img/forum/go_quote.gif
    This almost confirms that you've got bad solder connections at the pot, and that perhaps casing and uncasing it put enough stress on it to loosen some connections. The clicking is where the circuit makes contact through the volume pot when it's shorted (turned all the way up). The signal is partially diverted to ground before that, and as the volume control is adjusted upward, less and less signal is sent to ground. However, if the ground connection is not there, then the circuit is broken until the full-shorting connection is made, hence - no sound.



    I took it apart again and resoldered all the pins on the volume pot. No dice. Looking with the volume knob facing away from me the two on the farthest right dont want the solder to stick very well. What can I do to remedy this? And is there any way to test which pin is causing this problem exactly? Or would it be just one of those two no matter what?
     
  9. Entropy1
    FINALLY GOT IT WORKING! Turned out being the volume pot. I don't know how I didn't get this earlier as with just a bit of shaking it with music playing I noticed it. Everything is working great and it does sound good. The first thing I notice is the separation. Even with the amp and onboard sound, compared to my (now dead) x-fi card, the separation is much improved. The bass is also great and can really get my Senns moving. I'm not sure whether I'm a bit fatigued because of the volume I'm listening at (I'm splurging a bit on how loud I usually let myself listen) or if it's the onboard sound. I was pretty fond of my modded x-fi and loved it's balance and how smooth it was so there's still a bit to be desired on my end. I can't wait to listen to this thing with a decent DAC or sound card. I may post my results then, but until then, thanks for all the help and kudos to tomb for putting together this kit.
     
  10. the_equalizer
    Quote:

    Originally Posted by Narwhalius /img/forum/go_quote.gif
    I took it apart again and resoldered all the pins on the volume pot. No dice. Looking with the volume knob facing away from me the two on the farthest right dont want the solder to stick very well. What can I do to remedy this? And is there any way to test which pin is causing this problem exactly? Or would it be just one of those two no matter what?



    Solder doesn't stick very well because the pads where you want to solder those pins are connected to the boards ground plane. The ground plane is a sheet of copper the size of the PCB, thus when you apply your soldering iron to those pads, the big copper surface acts like a heatsink and sucks the heat out of your iron.

    This is my technique to solder to ground planes; I don't claim it's the best, but it works for me. With the part inserted in place, apply your iron to the pad only, not the part pin. Be patient, maybe move your iron a bit around the pad, as if you were trying to spread the heat. Obviously, if your iron has a temperature control, it helps if you set it near its maximum.

    After maybe a couple of minutes you'll notice that the solder in the pad really starts flowing. It is then that you want to apply the iron to the part pin too for maybe 3 to 5 seconds. Then apply a bit of solder. You're done.

    Quote:

    Originally Posted by Entropy1 /img/forum/go_quote.gif
    FINALLY GOT IT WORKING! Turned out being the volume pot. I don't know how I didn't get this earlier as with just a bit of shaking it with music playing I noticed it. Everything is working great and it does sound good. The first thing I notice is the separation. Even with the amp and onboard sound, compared to my (now dead) x-fi card, the separation is much improved. The bass is also great and can really get my Senns moving. I'm not sure whether I'm a bit fatigued because of the volume I'm listening at (I'm splurging a bit on how loud I usually let myself listen) or if it's the onboard sound. I was pretty fond of my modded x-fi and loved it's balance and how smooth it was so there's still a bit to be desired on my end. I can't wait to listen to this thing with a decent DAC or sound card. I may post my results then, but until then, thanks for all the help and kudos to tomb for putting together this kit.



    I'm glad you got it working Entropy1. [​IMG] Congratulations. Persistence does have its rewards, huh? Enjoy!

    cheers!
     
  11. Narwhalius
    Quote:

    Originally Posted by the_equalizer /img/forum/go_quote.gif
    Solder doesn't stick very well because the pads where you want to solder those pins are connected to the boards ground plane. The ground plane is a sheet of copper the size of the PCB, thus when you apply your soldering iron to those pads, the big copper surface acts like a heatsink and sucks the heat out of your iron.

    This is my technique to solder to ground planes; I don't claim it's the best, but it works for me. With the part inserted in place, apply your iron to the pad only, not the part pin. Be patient, maybe move your iron a bit around the pad, as if you were trying to spread the heat. Obviously, if your iron has a temperature control, it helps if you set it near its maximum.

    After maybe a couple of minutes you'll notice that the solder in the pad really starts flowing. It is then that you want to apply the iron to the part pin too for maybe 3 to 5 seconds. Then apply a bit of solder. You're done.
    cheers!




    Man I must have soldered that thing twenty times by now. Did what you said and I'm still not getting any sound out of the left ear. I've check my wires too. Both work in the R block.
     
  12. Lil' Knight
    Can you take a pic of how you soldered the volume pot?

    I also had a problem with the pot but a reflow fixed the it perfectly.
     
  13. Juaquin
    I like to use a heat gun for big ground planes. Warm up the board (not too hot!) and there's less work for the iron to do.
     
  14. the_equalizer
    Yeah, I think I read somewhere someone used a hot air gun on the PCB to get the ground plane going.

    cheers!
     
  15. Narwhalius
    Ok here's some pictures of the volume pot pins. Hope these aren't too big.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
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