GM/A 8.1 - BT/A 2.1 keypad screen dead

[vincmo]

Hello fellow KNX users,

I have a GM/A 8.1 system with 4x BT/A 2.1 keypads. 2x of them lost their screen function (the screen is still backlit but no informations are displayed). The system has been running for 5-6 years without any problems. After a complete shutdown (de-energized, batteries unplugged) and reboot, the keypads are still behaving the same. Anybody encountered similar problems with the BT/A 2.1 in the past? Any help or pointers would be much appreciated.

ChatGPT translation to German (so it might be funky):

Hallo liebe KNX-Nutzer,

ich habe ein GM/A 8.1-System mit 4x BT/A 2.1 Tastsensoren. Bei 2 davon funktioniert die Anzeige nicht mehr (der Bildschirm ist noch hintergrundbeleuchtet, zeigt aber keine Informationen mehr an). Das System lief 5–6 Jahre problemlos. Nach einem kompletten Neustart (stromlos gemacht, Batterien abgesteckt) zeigen die Tastsensoren weiterhin das gleiche Verhalten.
Hat jemand in der Vergangenheit ähnliche Probleme mit dem BT/A 2.1 gehabt?
Für jede Hilfe oder Hinweise wäre ich sehr dankbar.

[vincmo]

picture for reference: 1rst one faulty, 2nd one working

[Exun]

Hi, my BT/A2.1 (the white model) also stopped working after six years, showing the same symptoms—keys still respond, but there's no display.

[vincmo]

Thanks for the reply Exun. Same here; keys still respond but no display aside from the back light. I also had 2x BT/A 2.1 in white a couple years ago and they gave up after 1 year of use. It seems to be a common problem. ABB have retired the GM/A 8.1 back in 2022 with no replacements in sight. Parts are now pretty much impossible to get. If I may ask, what did you end up doing to fix the problem?

[Exun]

I'm pretty frustrated with the quality of this device. Since I couldn't fix it myself and several sellers canceled my order, finding a replacement became a real challenge. It's quite expensive, but I had no choice but to buy it to keep my system functional. I finally managed to secure one for about 500€, and it will be delivered in a week. Fingers crossed this one holds up...

Just a few weeks ago, my first battery died as well, but I found a third-party replacement (Banner Batterie Notstrombatterie), and it’s been working flawlessly ever since.

[vincmo]

I hear you. I bought into the ABB GM/A 8.1 system because all the devices are Made in Germany. Needless to say, I was not expecting problems on the quality side of things. Believe it or not, I had to re-do the soldering on one of the zone of the GM/A 8.1 panel itself. The zone was always showing as open and I could not figure out why. I un-mounted the main device from it's metal box to find a defective soldering on the circuit board behind the zone that was showing as open. I sent an email to a support contact at ABB about the QA defect and got no replies whatsoever. See the picture below of the defect before I performed the repair (the pin at the very right):

[vincmo]

Knowing that, it is possible that there is a defect in the BT/A 2.1 keypad that could be repairable. The thing about trying to source a new unit to replace the defective one is that on top of the high cost, there are no assurances that the new one won't behave exactly the same in a couple years.

I was wondering if:
A - Could this be a repairable defect with a permanent solution?
B - Should we find another solution? Like a more reliable KNX interface to use as a keypad to set/unset the system (for ex. the G1)
C - Other ideas?

Thanks for the tip for replacement batteries by the way.