Immaculate circuitry

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Daniel Beardsmore

09 Aug 2014, 15:05

Ever noticed how beautifully made Cherry's PCBs are?
Cherry G84-4135PTMDE PCB 1.jpg
Cherry G84-4135PTMDE PCB 1.jpg (746.66 KiB) Viewed 4348 times
Cherry G84-4135PTMDE PCB 2.jpg
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Cherry G84-4135PTMDE PCB 3.jpg
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It's always really nice to open up a keyboard and find a high grade PCB inside.

Cherry have yet to disappoint me. Alps PCBs very considerably in the quality of the finish, which may be dependent on which factory in which country the PCB was made. The one from the Apple M0116 is perfect though:
Apple M0116 PCBs.jpg
Apple M0116 PCBs.jpg (744.03 KiB) Viewed 4348 times
I was also really impressed with the PCBs in the Neve Necam 96 keyboard:
Neve Necam 96 PCB 1.jpg
Neve Necam 96 PCB 1.jpg (732.42 KiB) Viewed 4348 times
Neve Necam 96 PCB 2.jpg
Neve Necam 96 PCB 2.jpg (567.57 KiB) Viewed 4348 times
I don't know who made that, i.e. whether RAFI made the PCB as well as the switches, or whether Neve just had the switches ordered in from Germany.

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dorkvader

09 Aug 2014, 16:22

Yes, I love opening a keyboard and findind a beautiful PCB inside.

That's one reason I hate cherry. Their PCBs suck!

Cherry is such a mixed bag of quality, It's hard to even begin. Their keycaps, cable, unnecessary RF paranoia, controller, etc are all very good, and either top tier or close to it. However, the switch PCB, internal connector cables, case design, etc. are all extremely poor.

What do I mean? Well, just comparing the controller PCB to the switch matrix one: the controller is very dense, nice dual layer with plated through holes, beautiful ground planes, nice soldering.

The switch PCB is made of a cheaper material, on one side has a massive ground plane (that is properly grounded at least) and on the other is a bunch of thin traces, using odd trace routing, etc. They already have a two-layer PCB, it makes absolutely no sense why they couldn't have shelled out the extra few cents for plated through holes, maybe they decided to put it in the cable instead.

The PCB itself is also much thinner than the controller PCB, You'd think since it has to support the weight of the entire switch / keycap / hamfisted register monkey pounding on it that they'd at least go in for a "standard' thickness PCB, but that's not the case here! It wobbles all over the place unsteadliy and it's quite common to see examples with cracks running through the PCB, causing early failure. Your 50,000,000 actuations won't save you from this awful PCB.

At least their soldering is well done.

The internal cables are also terrible! Whatever it is they used to connect the two PCBs together is very stiff cable. It's meant to be plugged into a socket (which you do see on some boards: more on that later) but that's unnecessary, as you can't separate the two with the grounding wires which are soldered (with huge nasty globs, though they get a pass for that, as good grounding is always okay) On the boards where both sides of the cable are sodlered, the cable is usually too long, folded in half, and in at least two examples is so stiff it pushes the rear casing out making a nasty bulge.

The internal connenctor I mentioned? more often that not it's soldered on crooked. There's a standoff on one side that's present and another that's clipped. I have no idea why they did this but it's bad design, looks horrible, and absolutely not the level of quality I would expect from my $300 POS KB.

I have keyboards from the 1970's with better PCBs than cherry has.

Now I see the PCB you have pictured if from a G84 KB with ML switches. I have a similar keyboard You can make your own decisions on it. It has its ups and downs, and is in many ways nicer (or more acceptable) than cherry's large g80 keyboards but even from the reflection of my lamp on the PCB you can see the shoddy quality.

What's a good PCB then? I don't have pictures handy, but TG3 have always looked nice. access / tipro aren't usually bad. Check out what WYSE was able to do in the early 1980's. The reason for the traces everywhere is they needed a very "compact" switch matrix, and only had one-layer PCBs available. Cherry use a two-layer PCB and don't take advantage of it. It's somewhat inexcusable. Wyse also label the switches on the soldermask, which can be helpful.

Other good PCBs? Here's an NMB that even has an upper ground plane like the cherry. This is, however, better in pretty much every way (thicker, more dense, better coating / sodlermask, etc.)
https://www.flickr.com/photos/dork_vade ... 928081893/

The PCB on this Pinnacle video editing KB is also quite nice. I was very happy when I looked at it. Just about the only "issue' is the jumper wire (and even that is handled rather well, I would say). Given how much these things cost, You would expect good quality, so maybe it's not in the same "weight class".
https://www.flickr.com/photos/dork_vade ... 884809274/

Actually, looking through my collection, I don't think I have any PCBs that are worse than cherry. Even the PCB under my maxi-switch rubber dome is nicer. I will take another look to be sure. Maybe the CMstorm QFR is worse.

I will say again though: alt least their soldering is nice. They are also very easy to desolder.

andrewjoy

09 Aug 2014, 18:06

Always have to love a bit of PCB p**n

Like the filtering on that cherry controller too :). But i must say i do like me some hand laid out PCBs

Check out the PCB on the space cadet

http://deskthority.net/photos-f62/space ... t1381.html

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Daniel Beardsmore

10 Aug 2014, 01:23

"hamfisted register monkey" LOL

Yes, Cherry are indeed a mixed bag. I used to rest my left hand on the corner of my G80-3000, and as I hit keys with my right hand I could feel shockwaves passing through the case. The G80-3000 case is cheap and nasty; I don't get why they can't put an extra standoff or two in the middle to support the PCB and stop it bending inwards when you hit keys firmly.

What I love about their circuitry, which are is that all the switch legs remain perfectly straight and the solder is formed perfectly. None of that randomly bent legs and blobby soldering. Also, the solder mask doesn't look like it was slapped on with a tar brush like you get with some PCBs including some of Alps's. (The controller board on my G80-3700 isn't anywhere near as tidy-looking though.)

Hi-Tek did indeed make some lovely circuit boards, especially the pre-NMB ones that were clean and simple.

I love the diddy keycaps on that Pinnacle board, too. They look really useful for putting on compact keyboards.

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dorkvader

10 Aug 2014, 01:59

andrewjoy wrote: Always have to love a bit of PCB p**n

Like the filtering on that cherry controller too :). But i must say i do like me some hand laid out PCBs

Check out the PCB on the space cadet

http://deskthority.net/photos-f62/space ... t1381.html
Hand routed PCBs are sweet! This is from a hall effeck KB I have from 1977. The only pictures I could find were from me measuring the pin spacing. I'll probably frame the PCB once I desolder it (and replace it with a modern one + controller)
Image

Let's get more PCB porn in here!
Daniel Beardsmore wrote: What I love about their circuitry, which are is that all the switch legs remain perfectly straight and the solder is formed perfectly. None of that randomly bent legs and blobby soldering. Also, the solder mask doesn't look like it was slapped on with a tar brush like you get with some PCBs including some of Alps's. (The controller board on my G80-3700 isn't anywhere near as tidy-looking though.)

Hi-Tek did indeed make some lovely circuit boards, especially the pre-NMB ones that were clean and simple.

I love the diddy keycaps on that Pinnacle board, too. They look really useful for putting on compact keyboards.
Oh man, bent over switch legs are the worst! Completely unnecessary, and WYE did it on all the WY-50 keyboards, making them a massive PITA to desolder and service. forget that! you can see a few of the leads on the chips in the KB above are bent over. You can't really bend the leads on those hall sensors, fortunately.

I do still disagree about the sodlermask though. You can see the "grain" of it in your picture where it catches the light. Of course the only alps keyboards I have are (NIB) tee mount ones and the PCB in the IBM "pingmaster" chinese / japanese keyboards is very nice indeed. The build quality on that keyboard is also very very high. I plan to take some pictures of it sometime and make a good article.

The only hitek keyboard I have is my TI 911 video terminal. It still needs to be cleaned more, but I found the PCB to be unremarkable for the age (1980's, IBM from that time are much nicer, with the exception of the "mudsaver" of course. That PCB is quite different.)

I do like how they have a whole row of diodes at the top for NKRO. From what I was able to find, NKRO hitek boards are less common.
Image

Compared with this (similar age to the above, but similar design to the 1970's offerings) microswitch makes a very nice PCB indeed.Image

Here's what I mean about TG3. Ignoring the corrosion on this PCB, it's very nice! I still regret not taking more pictures of it
Image
Note the "waffle" ground plane, the extremely well labelled PCB, and the versatility of this PCB. Here they have included easy placement for LED resistors of three different values. TG3 know how to plan a board. I also like the plated through-holes (which are of above average quality) and the trace routing looks better than most (though it's harder for me to judge that, I much preferred it to that datacomp bluetooth filco I took apart.)

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Daniel Beardsmore

10 Aug 2014, 12:27

That TG3 PCB looks an awful lot like … whoever it is exactly who's making all these small Chinese keyboards like the Poker II (Vortex, or whoever they subcontract out to).

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dorkvader

10 Aug 2014, 22:28

Daniel Beardsmore wrote: That TG3 PCB looks an awful lot like … whoever it is exactly who's making all these small Chinese keyboards like the Poker II (Vortex, or whoever they subcontract out to).
Waffle ground planes are common: kinesis, TG3, Vortex use them now though there are differences. Firstly, the first several generations of vortex PCBs don't have round planes at all (look at pictures of Poker X, Pure and Race) though the more modern ones do (my poker II does) and there are differences. I haven't desodered it, but there's a lot of ground vias on the ground plane, indicating that there is a double ground plane over most the PCB. As you can see in the picture, the TG3 PCB does not have a lot of vias in the ground plane.

I took my pure and poker II apart if anyone wants to see. I like the idea of having a PCB appreciation thread. We can post pictures of Keyboard PCBs and our evaluation of if they are good or not (and why).

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Daniel Beardsmore

10 Aug 2014, 22:40

I took apart my Poker II shortly after I got it (earlier in the year); I have a load more photos still to go up on the wiki one day, but they're not great. I couldn't find a good one of the whole PCB — I was having too much trouble with reflections from overhead lights and split colour sources (pure white light from the flash, and red light from the strip lights).

jacobolus

12 Oct 2014, 05:20

Laptop keyboard with cyan Omron switches, nice PBT keycaps, and NKRO.. and a kind of cute PCB:
Image

I started desoldering, and then thought I might take a picture before I fully take everything apart.

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Daniel Beardsmore

12 Oct 2014, 13:30

And there's another thing I don't understand — the weird shapes of traces on keyboard PCBs.

Also, notice how the middle pin for E is forced upwards around a screw? I guess these were hand-assembled. The O key is the same, and Y has the middle pin presumably bent out of the way entirely.

The right-hand modifier arrangement looks weird, too.

jacobolus

12 Oct 2014, 19:51

Daniel Beardsmore wrote: Also, notice how the middle pin for E is forced upwards around a screw? I guess these were hand-assembled. The O key is the same, and Y has the middle pin presumably bent out of the way entirely.
None of the switches have any bent pins. They slightly shifted the diodes next to the "E", "O", and "F7" out of the way to fit the screws.
The right-hand modifier arrangement looks weird, too.
That’s arrow keys.

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Daniel Beardsmore

12 Oct 2014, 20:39

Doh, I was out by one pin all the way along.

jacobolus

12 Oct 2014, 22:14

Someone on IRC was asking to see the other side of this Omron PCB:
Image

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Daniel Beardsmore

12 Oct 2014, 22:26

Very neat!

I can see now what they've done with the bottom-right — no modifiers at all, just arrow keys offset by an entire row.

I assume you have amber Omrons already, right? Maybe we'll get to see how they differ from the cyan ones. (I still don't understand why there was so much variation with space invader switches, either.)

jacobolus

12 Oct 2014, 23:15

Daniel Beardsmore wrote: Very neat!
I assume you have amber Omrons already, right? Maybe we'll get to see how they differ from the cyan ones. (I still don't understand why there was so much variation with space invader switches, either.)
The cyan ones are not very tactile, but make a reasonably loud click. The amber ones are stiffer, much more tactile, and make an even louder click. The white ones (used for spacebar on an amber board) are the same as the amber ones but with a stiffer spring.

I’ll try to take some switches apart sometime and see if I can tell what differs between various parts.

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Daniel Beardsmore

12 Oct 2014, 23:35

I would be really interested to see if you agree with me about how nice the amber ones feel with the switchplate removed.

jacobolus

13 Oct 2014, 02:20

Removing the leaf from the switchplate side makes a minor difference: the switch is slightly lighter, and perhaps slightly less tactile. The sound is also altered somewhat.

Removing the switchplate (or even just the leaf) is certainly one way around the “premature actuation” problem that Omron switches suffer from. Not sure it’s the most useful solution in practice though.

The cyan switch has a slightly softer spring than the amber switch, but most of the difference seems to come from the click leaf. Swapping springs from amber and cyan switches makes the cyan switch just a little bit stiffer, and the amber switch just a little bit softer, but it’s an only slightly noticeable difference.

Visually the two click leaves look extremely similar, so it’s kind of surprising that there’s such a noticeable difference in feel between the two.

I find the cyan switch not tactile enough, and the amber switch a bit too stiff. Using an even lighter spring than the cyan switch spring could be nice for those who prefer something a bit lighter than the default amber Omron. I tried putting in a spring from a green XM Alps clone switch (I bought a bag of loose switches from someone who had swapped them out on his Ducky 1087XM board), and the feel was roughly comparable to removing the switchplate (though without the sound change). An XM Alps clone spring is slightly smaller in diameter than an Omron springs, so it works, but sticks to the little plastic post in the bottom Omron housing; not too tight though, as a light tug with some tweezers is enough to dislodge it.

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Compgeke

13 Oct 2014, 02:51

This here's another quite nicely done PCB from a Wyse 85 board.

Image
Image

mr_a500

13 Oct 2014, 17:15

I wouldn't say this PCB is "immaculate", but I like the design:

Image

The Victor 9000 Keytronic looks pretty nice too:
Victor 9000 Keytronic PCB.JPG

jacobolus

14 Oct 2014, 20:15

For contrast, have some not-so-immaculate circuitry:
Image

Edit: that really wasn’t worth it to save 1 pin (wanted to use 8x8 matrix for the keyboard instead of 7x10); for the other half I decided to just forget about the extra pin and make everything in nice neat rows:
Image
Last edited by jacobolus on 15 Oct 2014, 01:00, edited 1 time in total.

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Daniel Beardsmore

14 Oct 2014, 21:52

Oh, then you want the Solidisk ROM/RAM expansion kit in one of the Beebs I picked up:
Solidisk-flying-leads.jpg
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Yes, there are two flying leads soldered to the CPU. Well, were:
6502-disconnected-lead.jpg
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The machine still ran with that wire missing, although the expansion board stopped working ages ago when one of the wires came off during a routine contact de-oxidisation exercise. (I can't solder.)

More pictures:

http://telcontar.net/About/Beeb/

Reminds me of the "thing" attached to the bottom of the PCB on my Tulip-branded Monterey K102:
Tulip_ATK_030244_--_controller_(bottom).jpg
Tulip_ATK_030244_--_controller_(bottom).jpg (776.72 KiB) Viewed 3706 times

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Muirium
µ

14 Oct 2014, 21:57

Eeeew!

Parak

15 Oct 2014, 01:45

Holy bodge, Batman.

andrewjoy

15 Oct 2014, 10:13

that bodge is just err what !

Are they connecting everything to ground via some decoupling caps ?

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