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SWR SM400s: HELP!!!

Discussion in 'Amps and Cabs [BG]' started by gnome01, Aug 5, 2002.

  1. gnome01


    Oct 30, 2001
    Bronx NY, USA
    OK, I got a used SM400s less than 2 weeks ago, and it has already cut out on me several times. The sound will just completely drop out randomly. To get it back on the last time I cranked the preamp gain all the way up and turned the master volume up pretty high. When I tapped on my instrument cable (not plugged into my bass) it did make a clicking sound, so then I plugged my bass in. BOOM, after nearly blowing out my speakers, the sound came back. Could this have something to do with the preamp tube? I noticed a similar popping kind of sound when I'd remove it with the amp on. Hopefully it's a simple matter of just needing a new tube. Any input would be greatly appreciated.
  2. I had a similar problem with an SVT-II a while back... with that one, the input jacks had just shook partially loose so that they would work sometimes, but then cut out, and come back w/no apparent pattern.

    I took it to a shop, had 'em soldered back correctly and never had the problem again... you may wanna try that?
  3. gnome01


    Oct 30, 2001
    Bronx NY, USA
    hmmm, maybe, but when I play my bass through the amp, even if it doesn't make any sound the preamp and limiter lights still flash, so it seems that the inputs probably work.
  4. ihixulu

    ihixulu Supporting Member

    Mar 31, 2000
    South Shore MA
    Try this:

    Switch the amp to stereo, and see if the problem is with one or the other power amp. Make sure when you do this your balance control is centered.

    Also, see if you're getting a signal at the pre out (mono effects out on back).

    Keep us in the loop.
  5. gnome01


    Oct 30, 2001
    Bronx NY, USA
    The cutout thing does happen in either mono or stereo, I've checked extensively. Haven't tried the effects loop thing though - that seems like a good idea next time that happens. I did replace the preamp tube though so I'll see if that fixed it.

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