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Looking for tech help with a B2R

Discussion in 'Amps and Cabs [BG]' started by 5not4, Aug 27, 2001.


  1. 5not4

    5not4

    Sep 7, 2000
    Flint, MI
    I'm having some problems with my B2R and wonder if anyone else has experienced this.

    Equipment: 4 space rack with B2R, Behringer compressor and Furman PL-Plus into an 8 ohm SWR WM4x10.

    When line voltage levels drop below 110v the amp will go into a kind of cutout mode but it acts like the output goes full DC. The speakers will extend to their fullest travel and stay there. I know this is not good for the speakers and get the amp shut down as quickly as possible. Unfortunately, this happens intermittantly and always at an inopportune time.

    The fan is working and the amp is very clean inside and out. No cooling vents blocked with dust. The amp does get warm but not too hot to the touch. It doesn't seem like it would be thermal shutdown because I would like to believe that the output would shut off not shove the speakers out.

    I have opened the amp to clean and like I said, it's very clean. Some dust but nothing out of the ordinary. Date code stickers inside show August and September of '94 quality checks. I visually inspected for suspect components and such and found possible cracked solder joints on a couple connectors. I touched up these joints just to be safe but don't really know if this could be the problem. I work as an Electrical Tech but have very little experience with audio equipment, especially of this type.

    Has anyone out there experienced this problem or maybe something similar? Maybe I could save myself some time and money by fixing this myself if I knew where to look.

    Thanks for any and all input.
     
  2. phunky345

    phunky345

    Jun 20, 2000
    Missoula, MT
    Ok, I'm not an electrician or anything, so none of this stuff makes sense to me. But I play through the B2R, so this is very concerning to me. My B2r makes a funny noise like some kind of sizzle, after I play loudly on the amp, then turn it down to apartment-friendly levels. It cuts the volume way down and distorts it momentarily, then goes back to normal.
    Is this what you're talking about?
    If anyone knows what I'm talking about, please let me know!
     
  3. 5not4

    5not4

    Sep 7, 2000
    Flint, MI
    Thanks, PBG.

    This sounds like it might be a somewhat common ailement for Ampeg ?!? I'm sending away for some schematics and hopefully I can track down the problem. At first I was thinking this might be in the power supply section but now you've got me thinking it's in the output/power section.

    Just curious, did you ever contact Ampeg when your amp was doing this? If so, what was their response?
     
  4. phunky345

    phunky345

    Jun 20, 2000
    Missoula, MT
    Right now I don't know exactly what I should do. Ampeg's "warranty" says I have to have at least a copy of the original proof of purchase for the head. I bought the head slightly used (15 hours in recording) from Michael Roche of True Sounds of Liberty. Of course he must've thrown his receipt away, cause if he's a ditz like me, he doesn't ever think things like this happen.
    My amp's slowly going crazy, when I tap on the top of the amp (non-rackmounted) over the face area, it crackles a lot. It does the same thing when I tap near the power section. Is it supposed to? I know nothing about schematics, but this thing is acting kinda funky. I wanna sell it while it still is 95% functional.
     
  5. 5not4

    5not4

    Sep 7, 2000
    Flint, MI
    Thanks again for the help, PBG.

    Schematics will run me about $15. Hopefully the parts won't be too much, either. I want to try to repair the amp and continue to use it. I, too, paid $300 used and I've had it for about 2 years so I've gotten my money out of it, also. But I won't sell it off to someone else knowing it's got this problem. It will either be fixed or become a dust collecter.

    I haven't talked with anyone at Ampeg (SLM) about this but you say it's with the current relay's. Are the relays themselves failing or the components driving the relays? Just replacing the relays doesn't necessarily fix the problem. I also wonder what kind of latent damage has occured to the output drivers. The amp has always returned to normal after shuting it down for a bit. I will try to pick someone's brain at Ampeg.