This was one of the more unusual repairs (if there is such a thing) – tractor mower JCB D20/50 dead in the water, nothing working, was playing up but now doesn’t do anything, main pc board module failure suspected.
Was potted in silicone, so scraped off the bottom (came away quite easily as the whole unit stank of diesel, clearly covered in it)
Immediately spotted the problem – almost every single pin in the connectors was barely making contact:
and found this damaged trace:
It turns out that the diesel soaked silicone expands over time, gradually forcing the connectors out of the board! So they had to be removed (carefully as there were SMD components also embedded underneath)
After scraping away all the gunk from the connectors, they now seated nicely and all the pins poking through!
and after resoldering and securing the broken trace before covering with conformal coating:
Reinserted into its housing, back to customer and all working well again! Most satisfying as a replacement seems to retail for pretty much £500! Ouch!