Alan,
Many thanks.
Progress report:
I have removed IC3 and checked the 5V line which reads correctly at 5V off the regulator. I will need to get a replacement for IC3 but I do have a small stock of BS170 to replace the 3 x PA transistors and Q5.?
With IC3 removed the LCD display is now displaying correctly and the buttons and encoder are also working correctly ... but the regulator continues to get too hot to touch after just 10 seconds (despite have a small heatsink fitted). I am hoping that there isn't an issue with IC4 but for now the next activity will be to replace the potentially damaged BS170 to see there is a short somewhere causing the overheating of the 7805.
73 Carl M0ICR
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