Honeywell Smartfit Room Unit display problem ... ahh

[ianrichards]

Good evening and thank you for allowing me to join your forum.
I'm pretty handy with most things but this is driving me mad !!!
I have a Honeywell Smartfit programmer T8677B1006 7 Day Optimised Room Unit and the LCD display has stopped working.
I have checked the voltage to it from the base unit and it is 12v.
I therefore assumed that the unit was defunct.
I sourced a new old stock direct replacement and expected it to work.
Alas, it didn't work which I assume means that the fault is elsewhere.
I have checked what I can on the base unit.
240v in and 12v out.
The wire between the base unit and the room unit is good.
What am I missing ???
TIA
Ian
Freezing cold in Cornwall !!!

 

[seco services]

you checked both terminals on the 12v out

 

[CBW]

Any good?

 

[ianrichards]

Both terminals checked.

 

[ianrichards]

Think I’ll get hold of a replacement base unit