Please help w/Bogner Metropolis problem...

Discussion in 'Amps and Cabs' started by agentcooper2001, Feb 24, 2006.

  1. agentcooper2001

    agentcooper2001 Member

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    I just bought this amp and got it in today (I bought it used) It's the 30w 2x12 combo w/reverb. I played it for about 30 minutes today at lunch and it sounded and worked just fine. Loved it! I got home from work today and plugged in and played just a few minutes and then a loud hum came through the speakers and then a extremely loud crackling sound and then total shutdown. It blew a fuse. I went and got some new fuses (the exact same as the previous fuse) I installed the new fuse and the amp hums, but will not let any guitar sound come through. After a minute or so, the extremely loud crackling occurs and I see a flash inside the amp, so I shut it off before it has a chance to blow another fuse.

    I called Bogner and spoke with someone (not a tech) and he said pull the EL-84's out and see if it crackles or shuts down. I did that and it didn't shut down with no El-84's in it. I've tried two different quads of EL-84's and it still does this. One set is the the EI Yugoslavia tubes that came with the amp and the other set I already had are JJ's. Any idea what the problem could be? I would appreciate it. I'd sure hate to have to send this amp to Bogner and pay god knows what to fix.

    Curt
     
  2. agentcooper2001

    agentcooper2001 Member

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    if you have an idea of someone that may know about this, that I could e-mail, please let me know. I really want to get to the bottom of this.
     
  3. cranqued

    cranqued Gold Supporting Member

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    Hoping someone comes through soon, Curt.
     
  4. pedalcr8z

    pedalcr8z Member

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    Had a Mesa Lone Star Special do the same thing which was easily taken care of........it was a screen resistor.........same noise and symtoms as yours. I'd still send it to Bogner unless you had a local amp tech that is REALLY good.
    Good luck.:BITCH
     
  5. agentcooper2001

    agentcooper2001 Member

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    thanks, I hope it's not something too bad. I do have a local guy that knows everything about amps, so I'll try to have him look at it today. Is it a big deal to replace a screen resistor, if that's what it is? Any other thoughts on what the problem may be?
     
  6. pedalcr8z

    pedalcr8z Member

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    IF it's a screen resistor, it's a piece of cake.
     
  7. agentcooper2001

    agentcooper2001 Member

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    thanks for your advice. Hopefully that's all it is. I'm going to try to find out today.
     
  8. agentcooper2001

    agentcooper2001 Member

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    I took some pics, so hopefully one of you guys will be able to see something wrong.

    [​IMG]

    [​IMG]

    [​IMG]
     
  9. agentcooper2001

    agentcooper2001 Member

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  10. agentcooper2001

    agentcooper2001 Member

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    if you look in the first and the last pic, you can see some kind of dark spots in that tubing. Is that normal? Where is the screen resistor?
     
  11. agentcooper2001

    agentcooper2001 Member

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    anyone have a schematic for the Metropolis? Do you know what kind of screen resistors I need?
     
  12. agentcooper2001

    agentcooper2001 Member

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    could someone move this thread to the Amp Technical forum, so hopefully someone can help me. I would very much appreciate it. Thank you!
     
  13. cranqued

    cranqued Gold Supporting Member

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    I started a thread in Amp Technical Info to point to this topic.
     
  14. agentcooper2001

    agentcooper2001 Member

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    i got some 1 watt 100 ohm metal-oxide resistors. I think these are the same as the ones in the amp now. I don't think I'd have a problem soldering them in, I'm just nervous about getting zapped. How do you discharge the power in the amp?

    Thanks for pointing this thread out in the amp tech. forum.
     
  15. riffmeister

    riffmeister Gold Supporting Member

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    hey Curt, once you get things straightened out with the amp, let us know what you think of it. you seem to be a true EL84 junkie!! ;)
     
  16. pedalcr8z

    pedalcr8z Member

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    AgentCoop,
    Please don't take offense by this suggestion but you are not qualified to perform a "guessing game" repair on such a prestigious amp. It's one thing working on a $400.00 amplifier but you are about to butcher a meticously made amplifier and by some of the questions you are asking, I don't think you are qualified to do a repair yet alone trouble shoot an amplifier of the calibre of which you own. It is nearly impossible to look at pix and trouble shoot although I'm glad you posted them as it gives me some idea what Bogner is all about and it obvious to me that he's got some interesting ideas and the build quality shows obvious passion. For your own sake, box it up and send it to Bogner knowing that it will be aced or find a tech that even knows what it is.
     
  17. agentcooper2001

    agentcooper2001 Member

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    yeah, i defintely don't want to mess it up. There is one guy in town who builds amps and knows a ton about them. I'm going to get him to replace those screen resistors. If we do that and there's still a problem, I'll probably have to send it to Bogner.
     
  18. pedalcr8z

    pedalcr8z Member

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    Coop,
    Just because I had a similar problem with another brand of amplifier doesn't mean that's the same problem with yours......don't just automatically replace the screen resistors.........chances are the local amp guy may not have the correct parts either and have to get it from Bogner which means that you can send it to Bogner yourself and get it back in about the same amount of time and MAYBE not even get charged and know that some generic part won't be installed and change the character of the amp.
     
  19. agentcooper2001

    agentcooper2001 Member

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    what happened, according to a different amp tech here in town, was that the rectifier tube had some filament burn off and go to the bottom of the tube, which caused a short circuit and took out the screen resistors before blowing the fuse. I can pull all the EL-84's out and leave the rectifer tube in and it powers fine and doesn't really make any noise other than a very low hum. When I put the EL-84's back in and plug the guitar in, no sound comes through.

    He said it was due to the tube being upside down that would cause this. I hadn't had the amp upside down, but I remembered it was shipped in the box with the amp upside down. (the packing place double boxed it, but for some reason turned the box with the amp in it upside down when packing it) He told me that's what caused this to happen. Does that sound logical?
     
  20. riffmeister

    riffmeister Gold Supporting Member

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    hmmmmmmm......many amps run with all of the tubes upside down. :NUTS
     

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