The point I don't understand is that who is do that? He or someone else? What is the type of sentence? Passive, causative? When I translate this I see sentence as "He tangled his equipment". How would you rephrase this sentence like?
Generally speaking, you do not deliberately tangle your equipment [in something]. That is, you do not take a positive action to gather up your cables and wrap them messily around your equipment. But that is what the active verb "tangle one's equipment" would imply.
So we use the passive voice, and say you got your equipment tangled. It may have been your actions which caused the entanglement, but you did not do it on purpose; it was a by-product of some other action which you were doing deliberately.
In your example, most likely "he" was, in fact, the one who caused his equipment to become tangled. But he did not do it on purpose.
If it was some other agent entirely who caused the equipment to be tangled, then you would say "his equipment was tangled."