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How to test SWR fan?

Discussion in 'Amps and Cabs [BG]' started by tornadobass, Aug 31, 2003.


  1. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    The fan on my SWR SM-400S always used to run for 10 or 15 minutes after the gig.

    The last couple of gigs I did, at the usual volume, the fan wasn't on when I was done, even though the chassis was hot.

    Is there a simple way to test if the fan and fan sensor are working correctly?
     
  2. The simplest I can think of is to take a thin metal piece to try if the rotor of the fan will turn and keep turning for a few seconds. That way you know at least that it's not full of dust. If it doesn't run at all this way, it should at least be cleaned.

    My 0.02
     
  3. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    Play the SWR for him. If he smiles, you've got a fan for life!
     
  4. JayAmel

    JayAmel Moderator Staff Member Supporting Member

    Mar 3, 2002
    Aurillac, France
    Generally, the first 20 rows of audience at any 311 gig are filled with SWR fans.

    ;)
     
  5. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    Okay, guys...enough...I'll just take it to the shop.

    Right up there with those questions about how to "date" a Fender.
     
  6. chadds

    chadds

    Mar 18, 2000
    SWR chassis are supposed to get hot even if your fan is working. This wicks heat away from internal components.
     
  7. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    :D You guys crack me up.
     
  8. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    Thanks! The thing is, the amp's fan has always been running for awhile at the end of a gig, but it hasn't even been on for the last two or three gigs.

    I'm wondering if something might be wrong with the heat sensor. The case has been hot as usual.

    The only thing different is that I've been playing outside lately...on cooler evenings...I guess it's possible that the sensor gets cool enough just from convection cooling.

    If the amp's too hot, I assume there's a thermal shutoff...I've heard a few people mention that there's has done that on some gigs.
     
  9. Finger Blister

    Finger Blister

    Jul 8, 2003
    Open her up (i.e., top the top)
    Plug it in,
    Turn in on,
    Point a Hair Dryer at it for a few minutes.
    If heat sink is hot to the touch and the fan doesn't function; touch a 'continuity checker' to the red & black fan wire soldier points on the circuit board to see if the fan is getting juice.


    While it's open; throughly blow out the entire insides with compressed air & clean: especially inside the heat sink.



    Let me know if you need a new fan.

    I have a like-new original 43 CFM 24v Nidec (OEM for the SM 400-S.

    I also have a 51 CFM Mechatronics super high volume replacement upgrade for the SM 400-S that I bought directly from SWR.

    I still have 3 brand-new-in-the-box 24v high volume 39.6 CFM Panaflo fans. This is what I'm currently using in my SM 400-S because it's CFM to dB ratio makes it the quietest.
     
  10. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    Thanks! You gave me an idea...I tried the hair dryer trick earlier today but the fan didn't start up. Who knows why?

    Anyhow, I just pulled the top again (damn! a bunch of mismatched screws that only fit a certain hole). I traced the circuit board to the heat sensor and jumpered across the two sensor terminals with a little screwdriver. The fan came on, and then went off again when I took off the screwdriver.

    I guess that means either that the amp hasn't been hot enough to trigger the sensor or the sensor has failed.

    Boy! You had some working changing the fan. It looks like you had to pull a power supply board to get at the two screws on the bottom of the fan, yes?

    Maybe I'll try the dryer trick again to see if the fan might come on now that I know it's good and that power is getting to it when the sensor switch is closed.
     
  11. Finger Blister

    Finger Blister

    Jul 8, 2003
    If I could do it,
    it must of been easy.