Exploded electrolytic capacitors on 8015 multi funtion relay

When I connect the electricity on the timer after less then one minute I hear A little explosion and when I looked to the board I saw a blister on the capacitor.
I have maybe the electrolic capacitor not good mounted. :bulb:
The image in the manual is not clear at all. What posititief or negatief is not two see on the picture.
Even when I use microscoop to see what positief is. I saw a + so I have connect the smallest pin for positief.
Is this correct? :question: :question: :question:

No, this is not correct.
The longest pin is the positive and corresponds with the ‘+’ sign on the PCB
The negative (shortest pin) is marked with ‘-’ signs on the enclosure of the cap.
You will have to replace it.

Strange because the board work.
Will I have to replace them both?
Can I test the capacitors with multi-meter?
The explosing I thought it was of a to high voltage. Because on the power supply stands 12V and when I use the multi meter it was 16V.
When I use another power supply the board worked. :unamused:

You will have to replace them.
You cannot test them with a multimeter.
It might seem to work but it is more reliable with the cap in place.