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Author Topic: MP-2s get Very Hot - Rack fans  (Read 2142 times)

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Harley Hexxe

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MP-2s get Very Hot - Rack fans
« on: Time Format »

Hey Richard,

     Fans are always a good idea in a rack, especially if there are tubes involved. As I mentioned in another post, this is why I wanted rear rack rails on all my rack cases for the past 20 years or so. Even with the extra space at the top of a rack, it's still just sitting there and not moving. At least a clip-on fan will move the hot air out and flow the cool air in.
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MarshallJMP

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Re: MP-2s get Very Hot - Rack fans
« Reply #1 on: Time Format »

Hey Richard,

     Fans are always a good idea in a rack, especially if there are tubes involved. As I mentioned in another post, this is why I wanted rear rack rails on all my rack cases for the past 20 years or so. Even with the extra space at the top of a rack, it's still just sitting there and not moving. At least a clip-on fan will move the hot air out and flow the cool air in.

+1, I have for the moment a small one unit plate with 3 small fans in it, I put it between the MP-1 and MP-2 on the front. But I just bought a bigger 3 U one with 2 120mm fans which I'm going to install on the back.
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rnolan

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Re: MP-2s get Very Hot - Rack fans
« Reply #2 on: Time Format »

I like the idea of the 1 RU with multiple small fans that would work well in the new 4 RU rack I'm building.  I bought a cheap Chinese (Stagg) 4 RU rack yesterday, the one I was using was a custom rack, plywood with heavy duty everything, it weighs as much as the gear inside  :facepalm: .  The stagg is heaps lighter smaller etc. and has rear rails as well.  I could mount a 1 RU fan blade at the top from the back to cool down the MP2.
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Harley Hexxe

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Re: MP-2s get Very Hot - Rack fans
« Reply #3 on: Time Format »

Richard,

    Personally, I would prefer a 2U rack fan panel and mount one fan to pull air into the back of the rack, and one fan to exhaust hot air, (on the tube side of the preamp), out of the rack. I just believe that a bigger fan can move more CFM of air than the small ones can, and we are talking about a lot of heat that comes from the preamps.
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rnolan

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Re: MP-2s get Very Hot - Rack fans
« Reply #4 on: Time Format »

Hey Harley, I hear you, and that would be good particularly in this new 4 RU rack I just put together.  It's also got a B200s in it and they get very hot as well.  Not that I've ever had a heat issue over the years.
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Harley Hexxe

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Re: MP-2s get Very Hot - Rack fans
« Reply #5 on: Time Format »

Hey Richard,

     I haven't used the B200S in a small rack yet, but it would be the one SS poweramp that I would use since it's the best sounding one I've ever heard for guitar. I do have the two Peavey Classic 50/50's in the small racks at the moment and they definitely need cool air circulating in them. For this setup, I'll probably want to use two 2U cooling fan panels. One at the top and one at the bottom of the rack case, or at least, where the hot air from the power vents from the power amps.
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rnolan

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Re: MP-2s get Very Hot - Rack fans
« Reply #6 on: Time Format »

I used mine for years until it started making loud crackles. So bought a Carvin TS100.  I tried to have the B200s fixed twice but he didn't fix it and then didn't want to know  :facepalm: .  So MJMP suggested I re-flow the PCB around the power supply  :whoohoo!: , while I was in there I re-flowed all the solder joins, it's a pretty simple amp - worked a treat so I'm using it again in the 4 RU rack.  I've got a Carvin DCM200L in the 8RU rack, it's 1 RU and really light, works well, very clean and transparent and doesn't get as hot as the B200s.
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Harley Hexxe

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Re: MP-2s get Very Hot - Rack fans
« Reply #7 on: Time Format »

Hey Richard,

     I know one of mine needs new filter caps in it, probably needs the whole board re-capped just to be safe. I suppose I could reflow all the solder joints in mine fairly easily.

     Thinking about MJMP's solution of a 1U rack with 3 small fans spaced in between his preamps, it does sound like a good idea to draw cool air into the rack between heat producing units. I would still want the larger ones in the back though.
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rnolan

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Re: MP-2s get Very Hot - Rack fans
« Reply #8 on: Time Format »

Hey Harley, the re-flow is pretty quick and easy, and IIRC the bottom plate of the case comes off so it's easy to get at.  Obviously new caps would be a good idea, caps of that vintage are all going hard inside these days  :facepalm: .
I liked MJMPs 1 RU idea but mounted on the rear rails.  In a 4 RU rack that still leave a bit of space to plug in speaker and midi cables easily (and looks cool >:D ).
One bit of experience from when MikeB replaced his speaker jacks (in what was my first B200s), they have to be isolated from the case or it hums.  I think he broke one so replaced them with standard jack sockets and wired them to the PCB.  He then had to get some isolating washer thingys which fixed it  :thumb-up:
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Harley Hexxe

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Re: MP-2s get Very Hot - Rack fans
« Reply #9 on: Time Format »

Hey Richard,

Thanks for that tip! I didn't know they needed to be isolated. I would have been thinking that I might have left an open lead somewhere in the amp. The one definitely needs filter caps though, it hums like a hornet's nest. I wonder if F&T make caps that big.
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MarshallJMP

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Re: MP-2s get Very Hot - Rack fans
« Reply #10 on: Time Format »

F&T has a quite big range of caps, you just need to  know the size of them and the pin spacing and if they are snapins or regular pins.

I attached some pics of my fans, the small ones are 24V but I drive them with 12V to keep the noise down.
« Last Edit: Time Format by MarshallJMP »
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rnolan

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Re: MP-2s get Very Hot - Rack fans
« Reply #11 on: Time Format »

Hey MJMP, very nice  :thumb-up:

Hey Harley, maybe give it quick re-flow while you are waiting on caps, it may fix the hum?  Seems the solder joins around the power supply break down over time particularly from being humped around for years (and having to drive on bad dirt roads).  Mine has been good ever since the re-flow.
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Harley Hexxe

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Re: MP-2s get Very Hot - Rack fans
« Reply #12 on: Time Format »

@MJMP,

     Okay, I see how you did that front fan panel now, You just took a vent panel and added three small fans to it. Brilliant!

     One question I have for you though: When I replace the Filter caps, will I need a rheostat to gradually power them up like you do with a tube amp?

    @ Richard,

     The hum is definitely from the filter caps. They leaked.
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MarshallJMP

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Re: MP-2s get Very Hot - Rack fans
« Reply #13 on: Time Format »

Harley, no need to use a rheostat, the supply voltage is about 44V so..., if I have the time I'll open up my B200S and have a look at those caps so I can help you find a replacement.
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Harley Hexxe

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Re: MP-2s get Very Hot - Rack fans
« Reply #14 on: Time Format »

MJMP,

     44Volts????   Those are pretty big caps. I'm surprised to hear that.

     You drive the fans with 12 volts? Is that an independent power supply?
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