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B-15R not producing sound

Discussion in 'Amps [BG]' started by njkramer, Dec 2, 2013.

  1. njkramer

    njkramer

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    I have an Ampeg B-15R that I bought used about a year ago. It has worked perfectly since I bought it. It has stopped working recently and I am not sure where to start to diagnose the problem much less fix it. I had the head all tucked away in it's home to clean my home recording space. I hooked the amp back up and it powers up and lights up the ampeg logo etc. but no sound is coming out when I try to play through it. Any suggestions where to start figuring out what is wrong? I can obviously take it to a shop, but I would like to see if there in anything obvious that I should try first.
  2. Woodstockz

    Woodstockz

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    Preamp out to another amp. Line in from a preamp.
  3. njkramer

    njkramer

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    Thanks for the suggestions. I'm at work now, but I will try that when I get home. It's is my baby, and I feel unsettled knowing that it is possibly sick. I'm hoping I am missing something dumb (which wouldn't surprise me) and I can just switch the cables or something (I did try a couple different cables).

    Any other ideas, anyone?
  4. B-string

    B-string Supporting Member

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    How does the speaker connect? With a cable or through the amp latches? Don't keep powering it on without knowing for SURE the speaker is loading the amp's outputs.
  5. njkramer

    njkramer

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    it connects through a cable. how do I test if the speaker is loading the outputs without turning it on?
  6. JimmyM

    JimmyM Supporting Member

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    Disclosures:
    Endorsing: Ampeg Amps, EMG Pickups
    You plug it into another amp and make sure it works. Unfortunately, there could be a whole myriad of reasons why it's not working till you narrow down the problem. Anything from a dead tube to a broken speaker cable and a whole bunch of stuff in between could cause it.
  7. beans-on-toast

    beans-on-toast

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    You might have pulled a wire to the speaker off. I'd take a look at the wiring and make sure that the two wires are connected to the speaker. I'd run something into the speaker cabinet to ensure that it is working. If that checks out, look at the amp next.

    I assume that you checked the fuse. On the amp reset the switch that selects 6L6 or EL34. You din't want it sitting half way between one or the other position. Same thing for the impedance switch, reset it to 8 ohms. If you have another cab, plug the amp into it and see if you still have the problem. Try a different speaker cable. When the amp is in standby, and the power is on, do the tubes light up?
  8. njkramer

    njkramer

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    The tubes do light up when powered up and in standby.
  9. beans-on-toast

    beans-on-toast

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    Tubes light up. So far so good.

    Try the other stuff when you have a chance and let us know what happens. Usually it's something simple.
  10. Caca de Kick

    Caca de Kick Sponsored by Jagermeister Supporting Member

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    Those B15R's also use a (automotive style) lightbulb as a speaker fuse inside of the cabinet. Make sure the little filaments didn't pop or the bulb untwist from the socket.
  11. njkramer

    njkramer

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    So upon inspection in the cabinet the white wire going to the speaker had come off, and worse, the wire coming from the bulb/speaker fuse came off the board taking the solder with it. This SUCKS! I'm not sure how this happened.
  12. beans-on-toast

    beans-on-toast

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    On the plus side, the fix should be relatively easy. Have you been able to figure out where the connections go? I'm thinking that a cable somehow got tangled in with the wires. This can happen with Portaflex cabinets.
  13. njkramer

    njkramer

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    I do see where the cables go, the white cable was easy to reattach to the speaker, but the fuse cable connection to the board is a bit concerning as the solder came off completely from the board. I could solder it but I feel like I would have to take the board out of the cabinet and do the work on it. This being my baby, I am nervous to do this myself.
  14. beans-on-toast

    beans-on-toast

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    Does it look like this with the black wire going to a connector?



    [​IMG]

  15. beans-on-toast

    beans-on-toast

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    I should add that with the horn switch turned off (position 1) and the speaker properly reconnected, you can test your cab with your amp even with the light bulb disconnected.
  16. njkramer

    njkramer

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    yep, that picture is exactly it. the black wire from the bulb connected to the board pulled out at the board and the solder there came off completely.
  17. beans-on-toast

    beans-on-toast

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    It sounds like the connector came off at the board because of a bad solder joint. It shouldn't have been able to pull off that easily. You would think that the red connector would have disconnected first.

    If you resolder it yourself, scrub the spot with alcohol (you can use vodka if you don't have drug store isopropyl alcohol, methanol or acetone) first to remove any residue. There might have been something on there preventing a good solder joint in the first place. Then pull the connector apart and just solder the part that goes on the board. It helps to use a bit of solder paste flux (radio shack) with a joint like that. It will be easier to solder that way. Clean off any excess flux with alcohol. Then reinsert the red end with the black wire on it.
  18. njkramer

    njkramer

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    So to revive this thread, I am concerned in that the solder pulled the pcb trace off at the connection point when the solder came off.

    [​IMG]

    Here is the picture of the situation. You can see that the leads for the fuse connection are yellowish where the board delaminated and pulled off. on the board you can see that there is a small part of the trace on the board at the connection site but most of it is gone. Not sure how to deal with this.
  19. B-string

    B-string Supporting Member

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    It appears the important conducting trace is on the other side of that board.
    The yellow is old glue that was used to help provide some mechanical stress relief.
  20. P Town

    P Town Guest

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    You should be able to place the pc-mount spade lug back on the board, bend the leads over so the are close to the lands on the board, and re-solder it. You could then apply some CA glue to the base of the lug to help keep it in place, and you should be in business. Otherwise, you could crimp a lug to a short, (inch, or so long) piece of stranded wire, and solder it to the board.

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