Will-352865

Thanks 96RAF. So from a quick search into PTCs I see they get hot if they trip; this is the case. On further investigation the problem is with the variable resistor as if I twist and hold it at 0 the PTC cools down and I get 18V AC out on the pins. Soon as I let go of the VR nob it drops back to 2.8V and the PTC heats up again.

Hi. New to this, just picked up some old sets for my son's outing into the world of model railways. The locos need a bit of soldering to repair some dodgy wiring repairs but also the controller is now dead. Was kind of working on and off for a day but now no output. The power pack reads 18V across the plug so no issues there. The through AC reads 2.8V and the track DC supply reads 0V in all switch and resistor positions. I've popped it open and followed the board layout to test across positions. Bridging the power side of the 'link' to the opposing AC output I get 18V as I'd expect. Bridging from the otherside of the 'link' I get 2.8V so I'm guessing the 'link' is at fault. What is the 'link'? Is this the fault as I would assume this should be allowing the unaltered 18V AC power in through to the AC output pins. Thanks for any thoughts. I'm fairly good at replacing things and fixing the obvious but I'm not savvy when it comes to circuit componentry.