Computing > Embedded Computing

[Updated (3) 10th June] Raspberry Pi 400 - Quality Control problems?

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Before you read my documentation, know that I am not alone, as seen here:

~~~ I have received feedback from the lead designer of the Pi 400 ~~~

I've just received a Raspberry Pi 400 (USA version) to review. Off the bat, I can tell you things about it which I can't, for the life of me, fathom:

#1 The keyboard flex and "feel" - the KB demonstrates significant flex, and a kind of "clacky", hollow sound/feel when typing on it. Bear that in mind, I shall pick up on it again at the end.

#2 The rubber feet number only two - the front "feet" are moulded plastic mounds, as common with a few other similar products. The rubber used for the back feet is not grippy enough; I feel they would have been wiser to use high grip rubber, such as silicone, or other product (TPU?) - think of the rubber used on older "ThinkPad" or HP "ProBook" machines (namely my ProBook 6460b, which, when on a desk, a wild horse couldn't drag off! MEGA high gripping friction!)

#3 The micro HDMI ports:
~ The where/why these are used has been done to death, it's daft, but I'll skip over that - the fact is, they managed to label pins #1 and #40 of the GPIO header (moulded in labels on the casing), so why not label the main HDMI "HDMI (primary, for single monitors)" or similar? One would assume that HDMI port #1 would be the one on the left as you sit at the unit, ports facing away from you... nooope... I sat there for a few mins wondering why I got no video (okay, partial PEBKAC, but ya know... sort it out guys!)

Okay so back to the keyboard flex/hollow sound & feel:

I took mine apart - a VERY simple affair with a plastic pick, unclipped the two-part (upper and lower) housing, lifted the keyboard upper part, and was greeted by a 26 pin membrane ribbon cable which has "3M" double-sided tape on it, the other side stuck to the cable, CLEARLY meant to stick the ribbon down to the steel keyboard backplate, but the brown backing paper is intact, and the ribbon IS NOT stuck down.

Also of note, three or four heat-staked plastic "rivets" which hold the steel keyboard backplate to the plastic, had ALREADY broken off (I've used the machine TWICE, it's brand new). They are clearly cheaping out on the keyboard assy mfr - I am not sure how much I believe the whole "Made in UK"  thing, as the keyboard is obviously made El-Chinarado, and has a Chinese label on it. Fair enough, but HOW cheap do you need to go?

What is UTTERLY baffling, however, is the missed opportunity of having the keyboard assembly backplate and the large (2mm?) thick aluminium sheet which is a huge heatsink, in SUCH close proximity - parallel to each other across the width and height of the internal dims of the machine, and yet... THERE IS A GAP, a void between them, so that the keyboard is UNsupported apart from the edge of the mouldings where they clip together - this means the the typing experience is "okay-ish" but hollow, and the best word I can use is "clacky" - plasticky.

Whilst inside, I added strategically  ;D placed blobs of "White Tack" across the heatsink plate (the thing barely breaks a sweat, so heat is no issue) as a test analogue for some form of high density foam or rubber which I have to find, and ensured each blob was around 5mm high, and then clipped the two halves back together, and then pressed firmly and uniformly across the keyboard, to ensure the "White Tack" had settled and reached a level. The reason for this is to allow the heatsink plate to act as a support for the KB - which works!

... the sound and typing feel are almost NIGHT AND DAY! The "White Tack" absorbs resonance and "clacky" sounds, and transfers the typing load onto the heatsink plate. It's not as if I covered the ENTIRE heatsink in it, or in foam, just at "strategic" points (Okay, I winged it  ;) )

Why would they MISS OUT such an obvious, EXTREMELY cheap (moreso in bulk!) mitigation? Clearly their QC is lacking, I feel. I have attached my photos and audio files (where I compare the sound)

The complaints about the heat-staked "rivets" on the backplate, I have seen elsewhere also. No one seems to have mentioned the HDMI ports not being labelled. I am not sure why they wouldn't do that.


I have (semi-temporarily) laid "Sellotape" strips on the heatsink, sliced up a "3M" self-adhesive foam pad into little slices (around 20 I think) and stuck them at strategic locations ON TOP of the "Sellotape". My adding the "Selloptape" is to allow me to remove this arrangement, the fact being that consumer sticky tape is infinitely easier to lift off than "3M" MEGA grade, will-hold-an-elephant adhesive!

The result is a MUCH firmer, more solid typing experience with little if any "clackiness" or hollowness in the key feel. Also, these foam pads are very dense (closed-cell foam I'd think), and will likely reduce the chance of the heat-staked plastic "rivets" breaking off, to low or nil.

I see no bowing of the keyboard across its width (looking across from the right end, eye aligned with the surface) and I see only a VERY slight curvature from the bottom to the top edge of the keyboard, but that may be by design anyway. I hope this helps people, it sure makes typing a whole lot more enjoyable (I am hyper sensitive across all my human senses and perception, being able to still hear 18Khz sounds at the young age of 46!)

There is a concave recess where the heatsink plate is formed to contact the SoC, which I didn't add pads to - it seems redundant and a little pedantic to do so, and also I am unsure about how transmitting force directly down on the SoC, via that area of the heatsink, would affect the SoC.

Photos of the mod:

My experience: bought three units, returned one.

Always check it when you get from amazon, I mean before packaging it as a gift item  ;D

(the two units were gifts for two my best friends)

While what you are saying are certainly valid complaints, you do realize you are complaining about the "feel" and quality of a $100 computer, right?

The last time a complete computer was sold for that price, we got ZX Spectrum - and the design compromises on that are legendary. OK, not completely comparable, different era, but the point is that this is built down to a price, with cheap off-the-shelf components (like the chiclet keyboard), so that kids can bang this around for a bit and it will be cheap to replace/repair when they break it.

For a more serious use you would be better off just buying RPi3/4, stick it into a nice cooled/ventilated case and use an external keyboard instead.

That said, feel free to send your improvements to the Foundation, I am sure they will be happy (no seriously) to have them and may even incorporate the feedback into the next revision of the product. They are known to listen to their customers.


--- Quote from: DiTBho on June 05, 2021, 11:07:58 am ---My experience: bought three units, returned one.
(the two units were gifts for two my best friends)

--- End quote ---

You got rid of yours, but imposed two onto your friends?  :P

Nominal Animal:
Looks like you could easily cast some blobbets in low-durometer (aka soft) silicon, and just plop them in place for the same effect.  Cost is minimal, and with a suitable hardness (pretty soft, if you use say a dozen of them), results should be at least as good as you got with white-tack.

It would be interesting to see if soft adhesive silicon shock absorbers (meant for cupboard doors and such) have the right dimensions.  They're easily available in about a standard size at brick-and-mortar stores, eBay, Amazon, etc.  The ones I have (a set of 100 in a sheet) are very uniform, 8mm (0.31") in diameter, 2.5mm (0.1") in height, but I suspect they're too hard: a single one is enough to absorb the "bang" when throwing a cupboard door closed.

I often use gasket silicone (or whatever non-acid curing, usually platinum curing silicone putty; medical grade low-durometer is best, but kinda expensive) for similar purposes, from standoffs to vibration absorbers between chassis elements.

--- Quote from: janoc on June 05, 2021, 11:17:47 am ---That said, feel free to send your improvements to the Foundation, I am sure they will be happy (no seriously) to have them and may even incorporate the feedback into the next revision of the product. They are known to listen to their customers.
--- End quote ---
As long as you do not mention anything Open Source, or the FOSS/Libre Software Movement, or indicate such preferences.  They really, really don't like that.


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