Suck or blow

[sumday]

I recently bought cheap a Onkyo AV Receiver, one of the models with overheating problems...a TX-NR 905.
A brick shithouse thankfully all functional...the graphic chip on the HDMI board is still working.

I have attempted to alleviate some of the excessive heat issues by heatsinking the I.C.s on the graphics board but think some active cooling will be needed.
So...if I go with mounting a fan, do I force cool air in....or suck hot air out.?

[Firebottle]

Blow air in.
Turbulent air will 'stick' to the radiating surfaces better than laminar air and absorb more heat. Hence it is better to blow air over as the air is turbulent coming out of the fan (due to the blades chopping up the air).

[fatmarley]

Not sure how you're planning to do it but i've just recently built a new pc, so my knowledge is reasonably fresh on the subject.
Bigger fans are better because they can be run slower and make less noise than a smaller fan that is spinning faster to move the same amount of air. If you are using a pc fan, you can get filters to help keep dust out of your machine (they come in standard sizes). I use Arctic F14 and F12 fans in my pc because they come with a 10 year warranty and are good value for money.

Most agree that you are better off having more fans blowing in than sucking out because this helps keep dust out (assuming you have filters on the input fans). If it's a sealed unit i'd think about either having one big fan pushing air in and one smaller fan sucking air out or at least adding some vents to let the hot air escape.

Edit:

If you want to direct air straight over the problem area, the Arctic P14 will focus the air into a smaller area. These are more like what you'd get on a GPU or CPU, rather than the F14 that is just a case fan.

[sumday]

Thanks for the replies...I've dug around and found a couple of 12v fans, or from a old PC psu and one from God knows.
To keep noise down both are currently running on 6v wallwarts..
I have them just sitting on the lid....no room inside for a permanent mount...I have a friend who fabricated metal (called him a welder once and he nearly punched me)...I'll see if he can mount them in the lid without destroying it..

[fatmarley]

Make sure you use filters or you will fill your amp with dust in no time.

[Oddball]

Could you use 2 , one to input and another to suck it out?:) The thread title make me think of other things :eyebrows:

[MarginWalker]

What on earth is going on?

[Pharos]

My instinct is to suck out because the vacuum will then pull the air into the cabinet from all the source openings, and this will be very turbulent and reduce laminar flow. Blowing at the hot item will cause a bounce, rather than engulfment.

[struth]

Blow

[Edward]

I opened this thread only as I have a filthy mind. :eyebrows:

But as I'm here I'd suggest two fans - one blowing in and the other sucking out. As oddball suggests.

Typical PC way of doing things.

If you find the fans you have make too much noise try Noiseblocker fans - virtually silent at 1m. Or slow down your existing fans with resistors.

[sumday]

I'm blowing...
Although the receiver delivers 140wpc in stereo, I thought I could use a little more and so took advantage of the bridge mode.
I guess its now capable of north of 200wpc....but....even with the wick up its now running cooler.

I'm thinking this is a result of the individual amplifier boards sharing output and not working so hard.

I've long been of the opinion that due to the fast pace of development, older A/V receivers are a steal secondhand...but for 80 quid this one has really surprised me.

[fatmarley]

My instinct is to suck out because the vacuum will then pull the air into the cabinet from all the source openings, and this will be very turbulent and reduce laminar flow. Blowing at the hot item will cause a bounce, rather than engulfment.

That's the worst thing you can do because it will fill up with dust in no time.

[57charles]

We have AC Infinity over here - with a choice of top, front or rear exhaust. I think they would work in UK with a small transformer.

[Beobloke]

You could do worse than keeping an eye out for an Antec Veris A/V cooler like this one here:

https://www.ebay.co.uk/itm/ANTEC-Soundscience-Audio-Veris-Visual-Cooler-A-V-Cooler-Dual-Fan-2-Speed-NEW/293204568893?hash=item44445aab3d:g:nvAAAOSwqLFdZqn 2

It sits on top of your item and its fans pull air up through the item, into the bottom of the cooler and then push it out of the rear of the cooler. I have one for big power amp use and it's quiet and effective.

I don't think they're made any more, so you'll be relying on secondhand.

[Pharos]

Matt, I cannot see any correlation between dustiness and whether to suck or blow. Either way there is a need for airflow volume, and this air will contain dust, this IMO being best addressed by using a filter grid at the point of air entry.

My PC has three fans arranged in series, all of which blow to an outlet, hence they suck into the cabinet, and the entrance point does get dusty, this readily visible and hence hooverable.

[fatmarley]

Matt, I cannot see any correlation between dustiness and whether to suck or blow. Either way there is a need for airflow volume, and this air will contain dust, this IMO being best addressed by using a filter grid at the point of air entry.

My PC has three fans arranged in series, all of which blow to an outlet, hence they suck into the cabinet, and the entrance point does get dusty, this readily visible and hence hooverable.

Dennis,
You said "my instinct is to suck out because the vacuum will then pull the air into the cabinet from all the source openings" - If you do that, the air being sucked in through "all the source openings" wont go through filters. Any air going into the cabinet should be filtered to keep dust out.

[Pharos]

Dennis,
You said "my instinct is to suck out because the vacuum will then pull the air into the cabinet from all the source openings" - If you do that, the air being sucked in through "all the source openings" wont go through filters. Any air going into the cabinet should be filtered to keep dust out.

Unless all the entry poi9nts are filtered, (although not stated previously), of course the entry points must be filtered.