i would check the transformer offboard to see that it passes the signal as it should.-just inject a signal to the 200 ohm side and expect it to come the other side 6 times bigger(or whatever the ratio is)
i had a similar problem conecting an oep in my G7 until i found out i conected it wrong...
i had a similar problem conecting an oep in my G7 until i found out i conected it wrong...