Thread: Scion xB '06, in-dash Atom 330, Lilliput 889GL; details, pictures, links. Index: pg 1

Originally Posted by rdholtz

There's another option I've been considering; it might eliminate the need for a fan to pull air off the monitor by sending a stream of cabin air across the back of the monitor:

Cabin Cooling for the Double-DIN Chassis?

I can imagine wanting a supply of cool air to help maintain temperatures of the PC and PSU, unless the monitor-cooling fan blowing across the chassis does a good job. I'll check that out using MotherBoard Monitor or SpeedFan.

If I see the need to draw cabin air into the dash for cooling, there's a port I can open up -- it's the little rectangular block you can see a few inches above and to the left of the glove box handle.

Click image to enlarge.

From there, I could run a simple duct to pull air from the cabin to the chassis, probably aimed right near the top of the monitor. I could cover the dash opening with mesh or louvers. A thermostatic control for the duct fan could be placed at the downstream opening if I wanted to get fancy; otherwise, it would just pull whenever the ignition is on.

That could work and may not be too obvious.... i did the same thing with one of my dash top screens. Its CCFL and I knew it would build up heat so I had to fan it.



Its been painted black and molded to the dash since Nexson finished it. I just went to home depot and bought a little cap for dryer ventillation and cut a square out.

Originally Posted by HiJackZX1

That could work and may not be too obvious.... i did the same thing with one of my dash top screens. Its CCFL and I knew it would build up heat so I had to fan it.

Its been painted black and molded to the dash since Nexson finished it. I just went to home depot and bought a little cap for dryer ventillation and cut a square out.

Changing the Fan Location

That duct I envisioned turned out to be impossible. It looked good at both ends, but I couldn't find a gap large enough to snake a duct through between them. So now I'm in search of a better way to cool the monitor. Although I'd been planning to include a fan in the chassis end panel, I'm wondering if I couldn't simply cut cooling slits in the bezel top over the back of the monitor and let heat escape there. That would make the chassis easier to configure, since I won't need to figure out monitor fan placement.

The motherboard fan cools the GPU, not the CPU, and even that fan is pretty small. We have lots of small computer fans at the store, and one of them is bound to be usable as a supplementary fan powered right from the motherboard. Instead of building a duct, I'll simply plan to move more air around in the dash with that added fan.

Changing the Fan Location, Part 2

I liked the idea HiJackZX1 and I discussed -- a fan moving air around in the dash.

But I thought perhaps I could put a small fan on top of the chassis, and have it move air up and out of the chassis toward the bezel. If some air is moved out of the top of the bezel -- and thus out of the monitor -- then cockpit air would be drawn up from below.

At the store, I told Brian I need to review the top of the chassis and see if there's space for that idea. "See if this helps," he said, and gave me a new 24V replacement fan from a Toshiba. It's only 1.5 inches square, and 3/4 inch thick. If I plug that 24V fan into 12V current, it will turn at half speed, meaning it will be relatively quiet, but it will still move some air. I'll see if I can position it in the top panel of the chassis right at the end plate. It should help move air from the CPU/GPU area, and across the PSU as well.

I have to determine what voltage is available for fans at the motherboard fan socket. If that socket is only 5V, it may hardly be enough to move the fan -- that's less than 21% of the fan's rated voltage. But maybe that's enough to do the trick, and I bet it would be quiet.

If this fan proves to be too thick, I've seen other fans that are thinner -- much like the Atom's GPU fan -- and I can try one of them.

Cardstock Mockup

The next step in this process was to figure out how large the 2-DIN chassis can be. The basic 2-DIN dimensions are 7.08 x 3.93 inches (180 x 100 mm). My space is about 4.5 inches high, so I have some extra room at the top, and I'll use every bit of it. Although the Scion's opening is a bit wider than the DIN spec, that "extra" space is taken up by mounting brackets. Allowing for the roughly 0.040 inch thickness of the material, that means the internal width on the chassis will be just about 7 inches.

There is no depth dimension in the DIN specification; my head unit measured 7 inches deep. Of that depth, the Lilliput monitor will take up 1.25 inches, leaving 5.75 inches for the rest of the chassis between the monitor and the crossmember at the bottom. Above the crossmember, there's plenty of additional depth.

But there's a wire bundle crossing the left lower corner of the bay in front of the crossmember; it's the result of moving the head unit. That wire bundle shortens up the available space more, because it's about 3/4 inch diameter, but it only affects the left side, and there's still space for two hard drives in the bottom if they're offset to the right.

The position of the crossmember means the Atom board has to angle up from the dash end to the firewall end, and the PSU will ride at the top. I'll extend the top of the chassis to protect cable connections.

A quick cardstock mockup helped me develop a pretty good basic plan. I'm building it in Google Sketchup 7. As soon as I finish the preliminary version, I'll export some images and post them.

Sketchup Model

Here are exported pix of the preliminary concept, done in Google Sketchup 7.

Click images to enlarge.

The hole on the top is for the fan, which will pull air out of chassis and blow it past the monitor and out slits in the top of the bezel, taking heat with it. The slit on the end panel is for the Lilliput mount.

Hard drives will ride on the lower panel, and the mainboard and PSU will screw down onto standoffs on angle brackets bolted to the sides.

I'll revise my cardstock mockup to match this design, for proof of concept. If it works as expected, I'll go to the sheet metal version, then on to final parts. If something doesn't look right, Sketchup makes it easy to modify parts.

Originally Posted by rdholtz

Sketchup Model

Here are exported pix of the preliminary concept, done in Google Sketchup 7.

Click images to enlarge.

The hole on the top is for the fan, which will pull air out of chassis and blow it past the monitor and out slits in the top of the bezel, taking heat with it. The slit on the end panel is for the Lilliput mount.

Hard drives will ride on the lower panel, and the mainboard and PSU will screw down onto standoffs on angle brackets bolted to the sides.

I'll revise my cardstock mockup to match this design, for proof of concept. If it works as expected, I'll go to the sheet metal version, then on to final parts. If something doesn't look right, Sketchup makes it easy to modify parts.

Looks awesome, you dont think that maybe you should put slots or vents on the bottom sides of the unit, or do you think the back being open is enough for proper air flow?

Looking sweet

I was wondering about ventilation too. The open rear is a good idea but I'd suggest ventilation slots on the top of the case.

Originally Posted by HiJackZX1

Looks awesome, you don't think that maybe you should put slots or vents on the bottom sides of the unit, or do you think the back being open is enough for proper air flow?

I'm not convinced additional holes would add anything to the unit, and they might even detract. I considered using perforated material for the chassis, but I think I want to direct the airflow more than the open material would allow. As it is now, air will be pulled in the open end and exhausted out the top by the fan. On the way along that route, some will cool the GPU and CPU (there's another fan on the GPU), and I'm expecting some of that air in motion will help move heat from the monitor. The bottom sides of the mainboard and PSU will be open to airflow as well, and that will help keep them cool, too.

I'll know a lot more about how successful this is once I build the unit. If it works as expected, I'll simply call it a victory and move on to software tweaking. If it doesn't work as expected, I'll scratch my head and figure out what to try next.

Those "what next?" things would probably include replacing either or both of the fans with higher-volume units, but I'll start with these lower-output units for three reasons: (1) they're what I have, (2) I'm betting they'll be just fine for my low-heat-output system, and (3) I want to keep the fan noise down.

Originally Posted by MeeM

Looking sweet

I was wondering about ventilation too. The open rear is a good idea but I'd suggest ventilation slots on the top of the case.

You guys are ganging up on me, eh? Well, you do have me wondering, and after thinking about what you say, I've reconsidered. I can change the single top fan into two top fans wired to the same plug.

I'll make that design change. Thanks to both of you for getting me to think about it some more.

Originally Posted by rdholtz

I'm not convinced additional holes would add anything to the unit, and they might even detract. I considered using perforated material for the chassis, but I think I want to direct the airflow more than the open material would allow. As it is now, air will be pulled in the open end and exhausted out the top by the fan. On the way along that route, some will cool the GPU and CPU (there's another fan on the GPU), and I'm expecting some of that air in motion will help move heat from the monitor. The bottom sides of the mainboard and PSU will be open to airflow as well, and that will help keep them cool, too.

I'll know a lot more about how successful this is once I build the unit. If it works as expected, I'll simply call it a victory and move on to software tweaking. If it doesn't work as expected, I'll scratch my head and figure out what to try next.

Those "what next?" things would probably include replacing either or both of the fans with higher-volume units, but I'll start with these lower-output units for three reasons: (1) they're what I have, (2) I'm betting they'll be just fine for my low-heat-output system, and (3) I want to keep the fan noise down.



You guys are ganging up on me, eh? Well, you do have me wondering, and after thinking about what you say, I've reconsidered. I can change the single top fan into two top fans wired to the same plug.

I'll make that design change. Thanks to both of you for getting me to think about it some more.

LMFAO, I disagree with the slots on the top though, because that will limit how much air that top fan can pull out. If you keep the top sealed, the air has no choice but to leave the through the fan. That will create kinda like a sucking effect. Now when I say vents, I dont mean big ones that take up the whole sides. Maybe like 3 well placed slots down towards the bottom. I think the best thing to do is do your design first. Do some testing with speed fan, and if you over heat or feel uncomfortable, then add the slots. Now I didnt want to suggest this because it is over board, but you could always put 1 small fan one each side to draw air in, then the fan ontop to draw air out.