Amiga next-gen build: 2 motherboard repair & power supply

I‘m no stranger to the capacitor plague and effects of them failing. Wasn’t planning of repair/change of power supply a second time on this machine however. Time to replace parts on the actual motherboard. Seems the caps and/or regulator on this motherboard are highly suspect, either that or I’ve happened to been bit by a second power supply death.

Some time after the last repair the machine started experiencing shutdown as it heated up. On a cold boot it would be fine for halv an hour then instantly turn of, upon restart stay running five minutes then one, then only seconds. A trick you can use to try and r track down the error is using cold spray on various electronics to look what exact parts seem to fail once the machine gets hot. Commonly this would again be, those damned capacitors.

So first step get them of and replace with high quality over specified capacitors to rule them out of the picture to be the cause of fault.

Next what I chose where nice solid polymer oscon caps very fitting low esr caps fitting this application (some leftover flux in the old caps they did not leak, being solid polymer as well).

Now getting these through-hole caps on there demands some creativity, as they are ment to mount perforated through the pcb, but this is rather spots for surface mounted caps. I use some high temperature black silicon to mount them with some vibration support and legs rested at an ange in the pads.

Thought this would be the end of it, but oh no. Seems at this point the failing caps may have killed the PicoPSU dc to dc supply. Here I’m jumping it, connecting green and black to make it start the second I plug in the cable from the ac to dc brick/wallwarth. It actually show zero activity on any of the power lines 12v 3.3v 5. Only for a moment it sends a volt or 400mV to the ‘always on’ 5V line. +5sb. Seems a fault mode in the machine caused the dc-dc plug to die, can happen with failing caps I suppose. Alternatively the on board caps were not the issue, and the issue were only the dc psu. Well so next step get a new dc-dc plug, amazon next day a 200w version, I did note the one I used were a 65w should have been enough really.

Amiga next-gen build: 1 Sam440ep