DevTerm A06 assembly report

[rafial]

I put together my DevTerm A06 last night, and I thought I’d provide a quick report on the few stumbles I had in the hope of benefiting others. Overall the experience was very smooth, though.

First let me recommend the following thread, which contains a very detailed write up on assembling a DevTerm CM3 - I found it after I reached my first point of uncertainty (the wifi antenna), and it gave me the confidence to continue.

Devterm cm3 installation experience. including some details of the mistakes I made

[installcm3] I wrote this in Chinese, and then translated it into English with the Google Translate. If there is anything you don’t understand, please contact me. The original Chinese will be posted at the end. Install the screen. Find the fixed board and the screen. The front of the fixed board is for the screen, and the back is for the motherboard, printer, battery compartment and other modules , etc. Therefore, after installing the screen, you will install other components on the back of…

I did also run into the first issue that thread mentions: when you go to snap the screen down, if you just try to push down like it shows in the instructions it’s very likely you’ll catch the edge of the metal shield around the screen and bend it! I did bend mine a little, fortunately my initial press down was cautious and I only bent it slightly. I highly recommend the suggested approach of bending the plastic tab that holds the left side of the screen back with your hand, dropping the screen down, and then letting the plastic snap back.

The WiFi antenna was my first real uncertainty. The illustration is slightly ambiguous … I wasn’t sure if I was supposed to put it on the inside or outside of the plastic fin. After studying the diagram, and the part itself, I settled on the outside, and I believe that’s correct:

(I now suddenly realize that the fact that the printing on the part is upside down at this point makes sense, because you are working on the bottom side of the unit at this point in the assembly, and you’ll then flip the whole unit over!)

— breaking this post up since the forum software is chiding me for being a new user —

[rafial]

The most frustrating part of the assembly was getting the top half of the case on. Getting the front edge to line up snugly, and stay in place while pivoting it down over the keyboard and screen is very finicky. You kind of have to flex it a little to get it to snap over the keyboard. After you get it in place, check the front seam between the top and bottom of the case. If it gaps in the middle, something hasn’t seated correctly.

Then, if you are like me, you’ll now notice the black hunk of metal with blue film on one side that the instructions never mentioned sitting on the table.

This thread:

Keyboard sticky, heatsink extra

From the social media photos its the a06 core heatsink [image] And for the sticky keys, as I don’t have the unit yet I can’t say but for the GameShell, usually taking them out and filling bits of leftover plastic did the trick

Provides the clue as to its purpose. I got to have more practice removing and replacing the top shell while disassembling to the point that I could attach the heat sink. I peeled up the blue film and found a white sticky pad underneath, and lacking any firm guidance, I just centered it over the Rockchip on the main board and stuck it down. I’m very naive on heat sinks, isn’t there supposed to be “thermal paste” or something? Anyway, hopefully it helps.

[rafial]

Here is the heat sink as I applied it:

[rafial]

Finally, I discovered that the batteries I had bought are definitely too big to allow the battery compartment lid to be installed. I really wish there had been more official guidance on the battery. I wound up with the BAK N18650CK, which according to 18650batterystore.com is 18.7mm diameter. I got confused between that battery model and it’s non-button-top version, which is apparently slightly slimmer (18.35). But it seems like these stick out more than a fraction of a millimeter would imply. For now, packing tape must suffice to keep them in place:

I’m trying again with the Epoch 30P (also ordered from 18650batterystore) which claim to be 18.25mm – we’ll see, but the lesson here is that for this battery compartment, diameter is critical, but it seems like there is enough slack in the clips that a slightly longer battery wouldn’t be an issue. Also, after seeing how these fit in the clips, I feel like you probably don’t need button tops, but I’ll find out when the new ones get here.

Definitely would love to hear from folks who have batteries that fit as to what brands and models they are using. And also where they bought from, since I pretty much just Googled and picked at random.

Also, it seems like pretty much any available battery that I’ve seen is going to be fine as far as the continuous discharge rating, given that the smallest I’ve seen are still like 5 or 6 amps? Given that the instructions recommend at 2A USB-C charger, I’m guessing that’s well above the draw current to run the system.

Anyway, the upshot is that my DevTerm booted right up, and seems to run just great. I can definitely feel the heat coming off the bottom of the case where the mainboard is located, so it’s obvious that heat sink is needed.

Now to go explore the software side of my new toy!

[Petrakis]

@rafial

isn’t there supposed to be “thermal paste” or something? Anyway, hopefully it helps.

The blue pad is a thermal pad, commonly found in many components like GPUs

[adcockm]

I really hope there is official guidance posted soon about the heatsink.

Thanks for clarifying these issues @rafial, as I’ve seen hints of these in other forum posts but so far there hasn’t been any acknowledgement or update to the instructions so most folks will have to make the same mistakes over and over. That could be especially bad considering how it sounds like it’s easy to accidentally bend the metal around the screen, have batteries ready to go that won’t end up fitting, etc. The heatsink is particularly troubling. Sounds like the blue backing was just trash (covering the adhesive), but @Petrakis suggests it might be a thermal pad. Surely Clockwork folks know how it should be installed, since they included it. And if some folks don’t install it at all since it wasn’t mentioned, they might end up overheating their devices.

As a side note, it would be great to have a thread where folks post what batteries they are using that work too. (And also batteries that are known NOT to fit.) Even if Clockwork can’t comment on them or suggest any, it seems like a good thing for the community to do to try to help each other out.

[adcockm]

A similar thread about thermal printer paper would help too. Would be great to see a list of known working paper and known paper that doesn’t fit or is too thick to work, etc.

[rafial]

@Petrakis

The blue pad is a thermal pad, commonly found in many components like GPUs

Yup. To further clarify, the blue is a plastic film, which when peeled off reveals a thin sticky white pad on the flat side of the heat sink. Given that there was no other obvious way of mounting it, I assumed that the white pad was there to glue the heat sink on to the CPU.

[rafial]

@adcockm

known working paper

I bought a couple 50’ rolls from Adafruit and they seem to fit perfectly: Thermal paper roll - 50' long, 2.25 wide : ID 599 : $1.95 : Adafruit Industries, Unique & fun DIY electronics and kits

[foriequal0]

Almost everyone in this forum says only the length of the thermal paper, but I only could find vendors that specifies only the diameter in my country.

DevTerm thermal paper size limit

According to the 3d models, it looks like about 42 mm is the inner diameter of the paper enclosure. [Screenshot from 2021-08-01 08-44-36]

This helped me a lot. I bought rolls of 40mm in diameter. It fits well in the tray. I haven’t tried the 45mm one, but I think that it wouldn’t have fit in there.

[Petrakis]

its 57mm * 40 mm probably. I use 57*35 papers

[Nathan_Lee]

@adcockm

it would be great to have a thread where folks post what batteries they are using that work too. (And also batteries that are known NOT to fit.) Even if Clockwork can’t comment on them or suggest any, it seems like a good thing for the community to do to try to help each other out.

I second this. I don’t have batteries yet though. I’m really hoping that the ones I settled on actually fit and work.

[dianus]

@rafial

Yup. To further clarify, the blue is a plastic film, which when peeled off reveals a thin sticky white pad on the flat side of the heat sink. Given that there was no other obvious way of mounting it, I assumed that the white pad was there to glue the heat sink on to the CPU.

So to be clear, the blue film is necessary? how is the heaksink then secured to the compute board?

[redshift]

@dianus

So to be clear, the blue film is necessary? how is the heaksink then secured to the compute board?

You can throw away the blue film once you peel it off. The important part is just that you peel off the blue film to expose the sticky white pad underneath, which you stick onto the chip. That lets the heat sink can do its job keeping the chip cool. The picture from @rafial above (DevTerm A06 assembly report - #3 by rafial) should be the end result - you see the fins. The white sticky pad (under the blue film you throw away) is underneath, stuck to the chip.

[dianus]

Ok this is what I thought, there’s a bit of misinformation above. Thanks for the clarification!

[PiNYC]

I assembled mine today too. Some notes:

• I put the antenna on the other side of the plastic. This caused problems for fitting in the battery board. It was not clear to me how to do it from the manual. Now it’s stuck there forever so… oh well?

• The ribbon connectors were not clear also. You have to flip the little tab UP first before you can slide in the ribbon cables. I tried pulling the tab out, and one went flying across the room. Fortunately it went back in fine.

[javelinface]

If anyone has one of those guns you aim at a place to get thermal readings, I’d be curious to see where the heat is generated.
I accidentally left my gameshell in a bag while doing an overnight compile, and it rewarded me with a lovely melted heat map:


At least I could identify where the hot spots are!

According to official photos, the heat sinks are installed like this:

I’m assuming that this is an A04 and an A06 unit; with the latter having a larger heat sink.

The main CPU is raised up relative to the other soc components, meaning that after adhering (yes I removed the blue film :)), only that would be making contact.

In retrospect I’m wondering whether or not I should have perhaps applied some thermal pads on some of the components. The last thing I want to be doing is applying something that acts as an insulator, or worse still, has the CPU transferring more heat to, than is dissipated.

That’s something in general I fear regarding the heat sink. My fan is barely ever on. This means there’s no aid flow. Would the heat sink merely be insulating, with no place for the heat to be exhausted from? The fins look far too shallow and thick to be conductive. I would love fo see thermal readings with and without the heat sink applied.

On the note re: the top clip not closing properly, I initially got that. I had a similar problem with my DEOT shell for my gameshell, but not my clear one. Like gunpla, I find the clear pieces to be harder and less prone to warping, compared to the opaque ones. I got an opaque grey devterm, so assumed this to be the case. However it seems the OP has a clear one.

I came up with a solution when I built mine. There was a spare power button. The orange transparent rectangle. This was EXACTLY the right size to be uses as something to reinforce the retaining tab. That is to say, it wouldn’t push the chassis out, deforming and putting pressure on anything, but also wasn’t too small, as to end up rattling and falling off. It simply did its job of keeping things in place.
This is something that all Devterm owners should have, so should be a universal fix. You could even double sided tape or glue it down if you wanted to. I haven’t, but then again I’ve only owned mine for a grand total of one day.
Here’s some pics of the mod:
The piece

Alignment

The final result

[matrix]

I think this must be the A06 rite of passage: feeling this is easy, seeing the lcd frame bend and becoming overly cautious, get through everything with the instructions at your side but struggle aligning the top case, realise the heatsink isn’t in the instructions, open it back up to apply the heatsink, struggle to align the top, open it back up because you just noticed when you applied the heatsink you dropped the power button/one/both side panel(s), realise you are now expert at getting the top on, profit

[Godzil]

The pad which is on the heatsink is the equivalent of thermal paste, so do not use thermal paste.

There is another reason to not use thermal paste, the heatsink will not stick anymore.

[javelinface]

I was thinking keeping the adhesive where it interfaces with the main processor, and since the heat sink doesn’t actually make contact with the other onboard components, bridging the gap with thermal compound; not paste.
This kinda stuff.

I would probably remove part of the double sided adhesive that isn’t making any contact with anything, since I have no idea how two different thermal compounds interfacing would affect conductivity. I’d assume negatively!