Ambika midi in ground/earth issue

Hi all. Im having an ussue with my ambika. Its functioned fine for well over a year or so now… . But now as soon as I plug in a regular midi or 5 pin din cable. . It will lock up the machine. Any ideas? Thanks. - Shawn

start with switching out the opto. There are 4 parts in the midi circuit so it shouldnt be too hard to track down the fault. (OK1, R8, R9, D3)

Cool. Ill do that. Thanks man! I was thinkin the opto was first choice.

Midi is optically isolated - so the problem should be unrelated to ground loops.

Does it happen when plugging in a cable or when sending midi commands? If it happens when plugging in a cable which is unconnected on the other end, it should be a mechanical problem. Maybe some solder point is loosing the connectivity when the board flexes due to the mechanical stresses on the MIDI connector. Try to re-heat the solder joints on the board.

Can you further explain what happens, when the machine “locks up”?

this is simular to my issue as well. the machine will lock up and be non responsive when the midi cord is plugged in (after the opto seems to fail - im assuming?)