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  1. nick12345

    Eleven GX: Biasing issues

    Well, I replaced the output transistors and the issue remained. Then I noticed that Q15 and Q16 were installed backwards. :rolleyes: Not sure if I did that, or if they were like that all along and the previous owner never turned it up. I had replaced Q16 earlier and just installed it the same...
  2. nick12345

    Eleven GX: Biasing issues

    I looked at the schematic for the Eleven G (no X) and it shows the 4 ohm load detector. However, it's not quite the same circuit and it doesn't seem to be able to trigger the protection like this one is. I hate to throw $30 worth of output transistors at this thing if I don't have to, but I...
  3. nick12345

    Eleven GX: Biasing issues

    OK, did some more testing. The difference in sound between the channels was due to a misbehaving loudness switch. Some contact cleaner seems to have fixed that. The protection isn't kicking in due to excess DC on the outputs.* Instead, it has to do with that pesky additional protection circuit...
  4. nick12345

    Eleven GX: Biasing issues

    Well, I finally got the new trimmers today. I accidentally messed one up while soldering it in, but fortunately, I was able to pull a 200-ohm trimmer from an old electronics kit and use it as a temporary solution. With the new trimmers, I'm finally able to get the bias down to 22 mV on both...
  5. nick12345

    Eleven GX: Biasing issues

    I put a short across Re22 (same as Re21 but on the right channel) and got 2 mV between the test points. Looks like new pots should solve my problem.
  6. nick12345

    Eleven GX: Biasing issues

    I tested with an ohmmeter and confirmed your suspicion. Both of the trimmers appear to be going open at the lower end of the range. I’ll replace them and report back.
  7. nick12345

    Eleven GX: Biasing issues

    Haven't had a chance to try that yet, but I will. The trimmer is almost fully counterclockwise already; it's just the last little bit that makes the bias increase quickly. Also, I should've emphasized this earlier, but there are some components in the circuit that are not shown on the...
  8. nick12345

    Eleven GX: Biasing issues

    I measured about 2.21 V across De1 just now. If I try to turn the bias to full cold, it starts shooting back up quickly.
  9. nick12345

    Eleven GX: Biasing issues

    Qe19: 0.567 V Qe21: -0.569 V Qe23: 0.593 V Qe25: -0.595 V
  10. nick12345

    Eleven GX: Biasing issues

    The voltage is 2.411 V and it does vary with the bias adjustment. Vbe5 is -0.604 V and Vbe7 is 0.569 V.
  11. nick12345

    Eleven GX: Biasing issues

    Craig, Thanks for the reply! TP21 is indeed positive, and yes, that channel has a good bit of DC offset. I tried shorting the collectors like you suggested, and this brought the bias down to zero. I think I'll replace Qe1 and Qe3 with a matched pair to reduce DC offset on that channel, and also...
  12. nick12345

    Eleven GX: Biasing issues

    Greetings all! I posted a couple weeks ago about a Kenwood Eleven GX that wouldn't come out of protection due to a bad 2SC1845 in the amp section. Having fixed that, I've run into another problem. The receiver works and actually sounds good, but I've been unable to set the correct bias current...
  13. nick12345

    Eleven GX won't come out of protection

    I fixed it!! It was a bad 2SC1845 (Q16). It's shown on the board layout on page 1, near the right output stage. The hFE was like 5 instead of the several hundred it's supposed to be. It must be something Kenwood added or removed from the Eleven GX, and I have the wrong version of the schematic...
  14. nick12345

    Eleven GX won't come out of protection

    Thanks for the reply! The cathode of De20 is at 60.6V due to the relay being open. If I manually connect the collector of Qe34 to ground, the relay turns on and I have 25.8V at the cathode of De20. The 10.4V remains at zero when I do this. I'm actually not clear on how 10.4V is supposed to get...
  15. nick12345

    Eleven GX won't come out of protection

    Greetings all! I've been on a long hiatus from posting here, but I've been into audio more than ever lately. I've run across an issue that I'd like a bit of guidance on. I'm almost done with my bachelor's in electrical engineering, which makes this slightly more embarrassing. :P Anyway, I've...
  16. nick12345

    Scored a Fisher 210-T

    I spotted this today at the Habitat ReStore for sale "as-is". I assumed this meant non-working, and sure enough, when I plugged it in at the store, nothing. I pulled out the fuse and it looked fine, and decided to get it anyway. I ended up paying a mere $8 for it. When I got it home, much to my...
  17. nick12345

    Got a free Sony TC-660

    I have been on a long AK hiatus, but I had a few great finds recently and thought they'd be worth sharing. Among them, this awesome reel-to-reel (my first). It's in awesome shape and the only thing I had to fix was a pinch roller that wasn't moving up and down freely. Granted, I haven't managed...
  18. nick12345

    Subwoofer connection to an older receiver

    I've never tried these, but I think it would work fine. This one can be adjusted; not all of them can be. Just connect it to the "B" speaker outputs on your receiver. http://www.parts-express.com/boss-b65n-speaker-level-to-line-level-output-converter--265-4040
  19. nick12345

    Ceiling Mount

    It looks like you have typical PA speakers, often used for background music in stores and elsewhere. Your description of what they sound like is pretty accurate. For $120 you could grab a pair of these Daytons. Never heard them but they should sound a lot better than what you have, especially...
  20. nick12345

    What is that one thing you own that suprised you the most.

    Realistic T-120s, and the fact that I listen to them almost daily while my Smaller Advents sit unused.
  21. nick12345

    Cap question in Frazier Buckaroo's

    Thank you for clarifying; I've learned something new. I had always thought a non-polar cap had to have an AC voltage rating (which I've seen). One question though...why would it be necessary to indicate which lead connects to the outside foil if the polarity makes no difference?
  22. nick12345

    Cap question in Frazier Buckaroo's

    Wow...that's a polarized cap. This is indicated by "D.C." which means that it's meant for direct current (audio signals are AC). The side labeled "outside foil" is the negative side. Why Frazier would use such a cap in a speaker crossover is beyond me. Definitely replace this with a non-polar...
  23. nick12345

    Does Anyone Know What These Are?

    Pretty sure those are ~4" cone tweeters in there. Not a good sign.
  24. nick12345

    Optimus T-300 Speaker Refoam

    I ran into a similar problem when I refoamed my T-120s...one of the woofers rubbed at higher excursions despite the fact that I used a test tone. I, too, managed to remove the surround in one piece, shim the VC, and re-glue. I will definitely stick with shimming from now on. And sorry, I don't...
  25. nick12345

    What Is The Most Underrated Piece of Audio You Ever Owned?

    JVC AX-R551 integrated amp from a late 80s rack system. It has all the crazy bells and whistles like a full graphic equalizer and audio level meter on a digital display, not to mention the "acoustic expander" button that seems to mess with the phasing somehow to expand the soundstage. The build...
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