Re: Merc-o-tronic repair help. Home › Forum › Ask A Member › Merc-o-tronic repair help. › Re: Merc-o-tronic repair help. debeReplies: 103Topics: 0 October 25, 2018 at 10:00 am #84950 If this is the same circuit board, then check for 5V dc on pin 8 of the NE555 ic as shown for a start.