Replacing a fan on a Marshall AVT275

Discussion in 'Marshall Amps' started by JPEdwards, Mar 28, 2015.

  1. JPEdwards

    JPEdwards New Member

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    Hi,

    Does anyone know if it's a simple job to replace a grinding fan on a
    Marshall AVT275.

    In fact, where can I buy a replacement fan for a Marshall AVT275.

    I'm thinking of buying this Amp but the fan is very noisy and sounds like it needs to be swapped out.

    Thanks,
    JP.
     
  2. Sidewinder

    Sidewinder Member

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    I've done it a few times on my AVT 150. It's an easy job IMO. The 150 has two fans. It's likely that the 275 does as well.

    This is a fairly common problem with this amp series. I can't be sure which type fans are used in the 275 as I've never been in one, but I'd bet they're the same as the 150.

    The fans are available on eBay all day. The factory fans are bushing type. I read somewhere to switch to ball bearing, so that's what I did the second time around, and I purchased two extra as this amp is a keeper. Here are the specs for the fans I use:
    40mm 10mm New Case Fan 24V 6CFM PC CPU Cooling Ball Bearing 2 pin 688a*
    40mm 10mm New Case Fan 24V 6CFM PC CPU Cooling Ball Bearing 2 Pin 688A | eBay


    The connectors on the factory fan use a two pin plug type. The replacements are three pin, so I simply cut the plug/wires off the factory fans so I could solder them to the new fans. Put heat shrink tubing on the wires first, soldier, slide down the tubes and heat shrink them. Install back in and close it up. Make sure to use safe amp practices so you don't get shocked.


    If you need help understanding safe amp tinkering practices, there is plenty of info here, or ask someone.



    The fan swap is pretty self explanatory once you get into the 150 and probably the same for the 275, but I could be wrong. Once you pull the chassis, you'll know what you're up against, and which fans you're replacing. On the 150 the whole job took about an hour.
     
    Last edited: Mar 29, 2015
  3. slowcorrado

    slowcorrado New Member

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    It isn't too bad of a job. If you have a plain AVT275, there are two 40x40x10mm 24V fans. The hardest part is finding a proper fan. be sure to match the voltage. I also suggest getting either ball bearing ones, or the "maglev" type. You'll need to try and get something in the same amperage range as the originals to keep the speed (and thus "whooshing" sound) at the same level. Note: This job will most likely involve soldering or crimping your old fan plugs onto the new fan's wires.

    If you have a late model AVT275X, it has a redesigned fan section with a single larger fan.

    I may be replacing mine again as the set I just installed are too loud for my tastes. I'll gladly send them along to whomever needs them for a couple bucks + shipping. If you play louder than a bedroom whisper, they probably wouldn't bother you. :)
     

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