Answering an old post but though this might help anyone else searching for a Myson Post Purge circuit board. I ran the boiler (balanced flue) with the post purge unit bypassed for a week or so, but wasn't happy about the residual oil fume smell. I then found a Worcester post purge unit 87161463080 which does a very similar job. The board size is smaller though. Two of the old pcb mounting posts can be used, and two new holes need to be carefully drilled through the steel back sheet to suit the mounting posts supplied with the Worcester unit. There are 4 wires on the Worcester unit. Brown is permanent live, blue is neutral. The pink wire goes to the red feed in the terminal block from the boiler blower Santronic controller, and the yellow wire goes to the yellow wire on the terminal block. The two white wires on the old PCB went to the terminal block on my Myson bolier but didn't do anything.
Obvious warnings that you do this modification entirely at your own risk and that it is purely for information.
Tony, March 2015
