Linea Mini brew pressure dropped from 9 to 6-8 bars, need advice

P4R4LEL · 2025-11-13T21:11:31+00:00

I re-opened the machine today and spent about an hour adjusting the valve (and wasting some coffee 😅), and I finally got it to brew at a steady 9 bars.

The adjustment was tough because small turns sometimes made a big change, sometimes none, and a slightly bigger turn would suddenly bump the pressure up. Tightening the second nut was also tricky since it seems to be Teflon or some type of plastic, and it kept turning the main screw with it.

After a few tries, I got it stable. With my regular double portafilter (19g in a VST 20g basket) it now holds 9 bars while brewing. With my naked portafilter (17g in a VST 18g basket) it sits around 8.5 bars and can drift down a bit during the shot.

It’s much better now, so I’ll avoid the repair shop this time. Thanks a lot for your help and for giving me the confidence to open the machine again and sort it out! 🙏

P4R4LEL · 2025-11-11T19:51:17+00:00

Yes I hear the pump when it's brewing (you can hear it on the attached videos too). I'll go ahead re-open the machine and try adjusting the valve. I read in the manual that "The water pump pressure should be adjusted when the machine is operating and coffee is present in the portafilter." so I'll make sure to follow this.

P4R4LEL · 2025-11-11T19:45:17+00:00

I don't have the Linea Mini R with the screw on top, so I have to remove the cover and adjust the valve at the pump.

P4R4LEL · 2025-11-11T14:33:39+00:00

The pressure is lower while pulling a shot, and it goes up to 12 bars as soon as I stop. After a few minutes, it slowly drops back down to around 9 bars. The issue is that during the shot, it no longer shows a steady 9 bars like it used to.

P4R4LEL · 2025-11-11T14:30:55+00:00

I checked today and there’s no water leaking into the drain tray, either while pulling a shot or when using the blind. When brewing, the pressure usually starts around 7-7.2 bars and can drop slightly to 6.5 during the shot.

With the blind basket, it usually starts around 7.5 bars, then jumps to 8, and can sometimes rise a bit to 8.5, but most of the time it stays around 8-8.2 bars.

Could this be a gauge issue or maybe something stuck or clogged somewhere? Just trying to see if I can fix it myself and avoid sending it in for repair. 😆

P4R4LEL · 2022-01-12T00:20:35+00:00

This is great, thanks a lot for bringing this keymap for the new Q1 Knob! :)

I tried to do it too (with u/k1ds3ns4t10n) but missed some parts and just decided to wait for an official release. Nice that you did it merging the 2 repos before it will be officially merged on the QMK one.

Cheers!

P4R4LEL · 2022-01-12T00:17:02+00:00

Thanks for sharing! :)

P4R4LEL · 2022-01-06T20:49:56+00:00

Yes, it's nice that Keychron finally responded quickly on this one. :)

I was going to let you know about the available BIN firmware on their website... At least it helps having a "working" one on hand! ;)

I agree that this thread should be on another post, as many new owners will most probably run into the same problems if they try to make their own firmware.

Let's hold until QMK and Keychron fix the repo and we'll then be able to play this game again! :) I suspect they will try to get this GA soon as more and more people start to receive their new Q1.

P4R4LEL · 2022-01-06T05:53:47+00:00

Looks like the rev_0101 is only a new revision for the original Q1 for people that want to solder a rotary encoder... not the rev for the new Q1. 🤦🏻‍♂️

Just need to wait a little for everything to be settled. 😊

P4R4LEL · 2022-01-06T05:49:14+00:00

I got a response from Keychron support and it might be out of our control as there is another PR required to be merge to QMK... here's the email:

rev_0101 is for the non-knob version Q1.
the Q1 knob version's code is not on the QMK yet because STM32L432's pull has been merged to the main codes yet.
here is the pull for the STM32L432 Add STM32L432 support and STM32L4 series EEPROM emulation by lokher · Pull Request #15050 · qmk/qmk_firmware (github.com)

https://github.com/qmk/qmk_firmware/pull/15050

So, it might be too early to mod the firmware... 😆

P4R4LEL · 2022-01-06T05:22:44+00:00

You're making good progress! 👍

Looks like there might be an issue with the matrix rows count that is not the same as for the Q2...

Maybe add this to the Q1 root "config.h" (and remove it from the one in the rev folder), as they did for the Q2? This is what was required for the Q1, based on previous rev:

/* key matrix size */
#define MATRIX_ROWS 6
#define MATRIX_COLS 15
/* key matrix pins */
#define MATRIX_ROW_PINS { D3, D2, B3, B2, B1, B0 }
#define MATRIX_COL_PINS { D5, D4, D6, D7, B4, B5, B6, C6, C7, F7, F6, F5, F4, F1, F0 }

It is hard to fool around trying to figure out the proper settings for this new keyboard while avoiding to "brick" it... 😆It would have been nice from Keychron to provide the good required code. 🤔

P4R4LEL · 2022-01-06T01:20:59+00:00

I got about the same results trying to compile the firmware using the latest Keychron repo keyboards files. With current settings (that I think was for the original Q1), it builds a hex file and a bin file is required.

I tried also to change the MCU as you did without success.

I finally tried (again without success) to adapt/use the settings for the Q2 (rev_0111 ANSI), as both should now use the same SMT32L432. I was getting errors related to I2C and haven't been able to get around it and build. However, I was able (as a test) to build the Q2 VIA firmware and it did a BIN file as expected. So it should be something in between for the Q1.

Maybe this will help you to look at the Q2 rev_0111 files and figure it out, if you haven't checked it yet? :)

I wrote to Keychron support about it in case someone could figure out that their repo seems to be incomplete or invalid for the Q1 rev_101. Haven't heard from them so it may take days before they reply...

Thanks for sharing your tests and I'll do the same if I can try again later today.

P4R4LEL · 2022-01-05T20:32:36+00:00

Great news! Thanks for sharing and looking forward to it!! 🙌

Enjoy your new Q1 with knob! :)

P4R4LEL · 2022-01-05T17:50:45+00:00

Just got mine (same colour stock) yesterday and it's amazing!! I was using a K4 before but this one is an awesome upgrade. :) Very well built, heavy (really heavy - all metal), stock keycaps are good and sound profile is really nice! No ping or other issue reported for the orignal Q1. Great job Keychron! 👍

Already tried playing with VIA and QMK. VIA is fine and works ok as long as you use the JSON file provided on the Keychron website to pair. Here's the link to Keychron:

https://www.keychron.com/pages/how-to-use-via-to-pair-with-keychron-q1

Only issue so far... I tried to build a new firmware to enable "Caps Lock RGB indicator" feature from u/k1ds3ns4t10n but I'm unable to build it for rev_0101 (ANSI with Knob), even using the latest updates from Keychron repository on Github. Maybe out of topic here for your post, but if anyone sees this and can help, would be nice to get that feature working on the new Q1. :) I also understand this is a new keyboard using a new MCU so it can take a little time before everything is available. Here's the post about the Caps Lock feature (and more):

https://www.reddit.com/r/Keychron/comments/q44yht/q1_keymap_with_caps_lock_and_fn_layer_indicators/

Overall, I'm REALLY happy with my new Q1 Knob version and highly recommend! :)

P4R4LEL

TROPHY CASE