bpt intercom

I have moved into a (rental) house with a bpt 200 system, consisting of a VA/200 and several YC/200 answerphones, just like this: https://doorentrydirect.com/media/product_attach_files/1/x/1xmu_abk.pdf. The system has one main problem, which is that it only provides 7V to the locking mechanism...

Hi, I hope you can help me with some trouble-shooting advice regarding a BPT intercom system. It comprises: one AS C-200 receiver unit (in the hallway), one A/200N controller unit (in the garage), and one HA/200 audio module (at the gate). It is wired exactly according to the diagram on page...