Problem:    "Won't boot; dead buck controller" 
Solution:   Replace buck with LDO with enable 
Brand:  Roberts 
Cost new:   £80 
Cost of fix:    £3.50 
Age:    5yrs	 
Success?:   Yes 

At this point I have fixed three Roberts radios so I'm somewhat the expert. Customer brought this in and wouldn't boot or show anything on the screen. Found the schematics and the service manual that gives you a flow chart to diagnose and look for voltages. One of the main supply voltages after the power in wasn't being produced! There should be a 5.3V rail being generated, but it wasn't present at all. That rail is generated by a buck controller that was sending a constant voltage to a MOSFET, so the controller was obviously dead. I tried looking for replacement parts for that controller in the same package, but to no avail. They use bucks for efficiency as this radio is able to run from batteries, but I'm not fussed about efficiencies for repairs like this. I found a suitable 5.3V LDO that I had kicking around that also has an enable pin. Wired up my little abomination with enamalled wire and hey presto! Working radio!! I think there's still an issue with something on the LCD screen as the contrast isn't that high. It's getting the necessary power, but there are supposed to be some configuration resistors but I couldn't find a datasheet for the LCD so that's as far as I was willing to go for that.