Flush-mounted shutter timer

Kaiser Nienhaus 320000 Tastor Konsum Shutter timer, flush-mounted.

Shutter timer with RTC, programmable up/down times with option to add random delay to these times to simulate presence and manual control.

KN 320000

KN 320000

Detachable screw terminal with Line, Neutral and two outputs for up/down directions.
KN 320000

KN 320000

Three buttons + one semi-hidden (reset). It seems that same PCB might be used for other models with more buttons.
LCD using rubber zebra strip.
KN 320000

PIC16LF1937, 8-Bit CMOS Microcontrollers with LCD Driver (up to 96 segments, contrast control, internal voltage reference selection) and nanoWatt XLP Technology, 1.8V...3.6V power supply. 8k * 14bit FLASH, 512 B RAM, 256 B EEPROM.
ELNA 0.22F/3.3V backup capacitor.
KN 320000

Transformerless power supply. Rated power consumption: 1 W.
KN 320000

Two HF32FA-G relays. Rated switching capacity: 1250 W.
KN 320000

KN 320000

KN 320000

I have two pieces of this device and one of them is having issue with backup power. At first I though that this was caused by missing solder joint (see photo), but it is not soldered on both pieces.
KN 320000

KN 320000

Second - working - piece:
KN 320000

At the moment I have not solved the issue with backup power. Supercap seems fine, same as 100 uF / 25 V capacitor.

Manufacturer claims 0.5 minute battery backup, but this seems to be an error in documentation. In my test working piece was keeping up RTC for 10+ minutes, so maybe this should be 0.5 hour instead?

UP/DOWN times seems to be stored indefinitely, likely using EEPROM.

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