How can I cool my cabinet?

Discussion in 'Archived Threads 2001-2004' started by Ralph Summa, Dec 7, 2001.

  1. Ralph Summa

    Ralph Summa Supporting Actor

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    Here's my story:
    I have a Yamaha receiver that gets extremely warm in my enclosed cabinet.Here's the cabinet, and the components are behind the right door on separate adjustable shelves. I can't leave the door open because of WAF (or lack thereof) and my 18 month old has a love for electronic equipment.
    Someone just gave me a neat little rack with two 115V AC 120 mm fans that run at 3100 RPM and 45dB. They each move 110 CFM which is overkill and the fan noise is too loud, It can be heard over regular TV listening volume even with one fan disconnected.
    I have drilled holes in a circular pattern, (17) 1/2" holes on each shelf in preparation for installing the fans at the top of the cabinet. Unfortunately moving the fans closer to the holes at the top will make the noise even more audible.
    My thinking was to cut down on the fan speed and thus the noise.
    I noted that people were adding resistors to the power supply of internal 12V fans but I'm not sure if it could be done with house current. (Sounds like a Darwin award to me!) I could pick up a few quiet 12V fans real cheap, but how do I power them? I guess I just want to work with what I have, if possible.
    I searched all over for information on fans and I read a post that said AC motors should never be dimmed. Is this true? I saw light dimmers at HD that weren't dial-type rheostats. They were push button type preselected dimmers. Can these work and can they work without introducing hum? Are fan dimmers and light dimmers different?
    I don't think I can set up a duct ventilation system because my cabinet is flush to an outside wall that is insulated.
    Anyone have any ideas?
    Thanks,
    Ralph
     
  2. Kendal Kirk

    Kendal Kirk Stunt Coordinator

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    It could be that you are having to push your Yamaha to hard to get any sound out of those little speakers [​IMG] [​IMG] !!! Just kidding. . .
    I have installed fans on the top of my receiver that sits on open shelves. I used computer power supply fans, and powered them with a common DC to AC adaptor that I had from an old computer speaker set. You can get a good selection on fans from Radio Shack.
    You may want to remove the fans from the rack that you received and install them on the back of the cabinet close to the top, close up the majority of the holes accept at the bottom of the back of the cabinet something like this:
    -------------
    : X X :
    : :
    : :
    : :
    : :
    : 0 0 0 0 :
    -------------
    Hopefully the selves are flush with the back of the cabinet to allow for air to flow along the bottom shelf, up and over the back of the door, and out the fan.
    Just my $.02
     
  3. Wayne A. Pflughaupt

    Moderator

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    Ralph,

    Sure wish you would have posted here before you cut holes in all your shelves. I don’t think it was necessary.

    By doing that, I assume you have the receiver on a lower shelf and the other gear above it? All you need to do is install the fan in the compartment the receiver is in, not at the top of the cabinet. Just install it in the back panel, directly below the shelf above the receiver. Then it will exhaust the hot air out of the cabinet before it can rise up to the rest of the equipment.

    I have similar fans, 4” so-called “muffin fans” that are 110VAC. I have been using a standard rotary-knob light dimmer on them for more than seven years, and have had no problems.

    Just as you found, they were moving way too much air and were very noisy. However, I found that using the dimmer made them hum, which in turned caused sympathetic vibrations in the panel they were mounted to. To deal with that I took a couple of other steps. First, I trimmed the intake hole with a piece of adhesive-backed weather stripping, which sealed the parameter and isolated the fan’s chassis from the panel. Then I enlarged the mounting holes and installed small rubber grommets. I found that using only two of the four mounting screws helped reduced the vibration noise, as did leaving the screws only snug-tight.

    In the end, I was able to substantially reduce the fan speed, and the hum/vibration level is so low you don’t even notice it.

    By the way, you are going to find that air movement = dust build-up.

    Happy Holidays,

    Wayne A. Pflughaupt
     
  4. Glenn Baumann

    Glenn Baumann Stunt Coordinator

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    Ralph,
    The best way to attack your problem would be to utilize 12 volt DC cooling fans and acquire a variable voltage power pack, also referred to as a wall wart, that usually has 5 to 7 selectable voltages such as (2, 4.5, 6, 7.5, 9, 11 and 12 volts) etc. You have to realize that the 12 volt DC cooling fans WILL still operate on lower voltages other than 12 volts! By utilizing the 6, 7.5, 9 or 11 volt settings you reduce the fans RPM thus you also reduce the decibel level and resulting noise level. Simply put, by experimenting you should find a level of voltage/RPM that still cools but is tolerable in the noise department.I have implemented this strategy before with excellent results! Just be sure to divide the total amperage output of the power pack by the amp draw of each cooling fan to make sure you can drive the amount of fans you desire. In this manner, I have created systems using up to 8 fans simultaneously with one power pack. Radio shack has these variable voltage transformers but they are very pricey, as in almost $40.00, but you should be able to acquire one through an electronic supply house for about $15.00 or so. As far as the cooling fans go, you can try a company called PC Power & Cooling, they have some efficient yet quiet designs and their link is http://www.pcpowercooling.com/produc...rfan/index.htm
    Good luck, hope this helps!
    Regards,
    Glenn
     
  5. Mike_P

    Mike_P Agent

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    If you can, make openings in the back of your cabinet. Your cabinet may already have precut openings that you just have to open up. If you have a large opening at the bottom and the top of the equipment cabinet, convection will naturally let the hot air out the top and pull cool air in the bottom.

    Another idea for maximum airflow would be to take the back completely off of the cabinet, but your wife may not approve. Of course, if you take the back off carefully, you can always put it back on in the future. Either way, it would be completely silent.

    If you want to use muffin fans, you can get 110 volt fans so you don't need a power supply. You can get fans from Allied Electronics or another electrical supply store on the web. Just be sure your electrical connections are well insulated and in a place where you toddler can't reach them! Also, you don't want to get into the 110 by accident when you're reaching for cables in the back of the equipment!

    Mike P
     
  6. Ralph Summa

    Ralph Summa Supporting Actor

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    Thanks everyone for your help. I ended up going with a 4-Speed fan control from Home Depot ($11). Strange though, three of the four settings don't seem to change the speed of the fans. The fourth setting cuts it down quite a bit. Very quiet, no hum. The fans right now are resting on top of the receiver and they are keeping that cool, the Hughes still is warm. As of right now, here's how the components are stacked.
    -----------
    CD Player
    -----------
    Receiver
    -----------
    VCR
    -----------
    Hughes STB
    -------------
    2' x 2' x 2'
    empty space
    -------------
    I can't move the receiver to the very top because of cable and wiring constraints, and I figured having the warm Hughes box at the bottom to keep the two hot components far from each other.
    The reason I chose the fan control after reading your posts was that my cabinet is installed directly to the wall studs, floor and ceiling. There's no moving it. If you drill through the back panel you are into the fiberglass insulation. There is a small "half moon" in the back of each shelf for cables to run through but it never really helped with cooling. That's why I drilled the holes. In hindsight I see that I may have drilled them in the incorrect places. I'm good with wood filler though!
    The two modifications I have come up with to my present situation are:
    (1) Pull the fans out of the rack and place one on the Yamaha and one on the Hughes box to see if it cools them as individual components.
    (2) Temporarily rig the fans right at the top vent to cool the entire cabinet.
    Any additional ideas comments would be great, except for Bose cracks Kendal! [​IMG] I got all my speakers at about 70% off of the retail price which is probably what they are worth! Springtime should bring me some new speakers.
    Thanks again to everyone,
    Ralph
     
  7. KevinMcL

    KevinMcL Agent

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    I bought a variable power supply from a dollar store for $9. I use it for exactly the same purpose, but for cooling my Rx which I use as a shaker amp. I have it at about 4.5V, but can increase or decrease it at will. I had to cut the supplied power plug off- the round one which accepts the universal round power plugs, and crimped on a pair of female slide-on connectors. These fit perfectly over the terminals of the fan.

    Good luck!
     
  8. Robert M

    Robert M Agent

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    I have the same problem with fan noise, (two fans mounted on top of enclosure). What I did was buy a small air cleaner and put it in the bottom of the cabinet, I leave it on all the time, and it is very quiet. The added bonus is that the air moved within the cabinet is filtered before passing over components, and dust has all but been eliminated. If it gets very hot in the cabinet, a thermostat engages the two exhaust fans.

    Bob
     

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