:? I assembled 2 X MK138 thermostat kits but both do not work.
Firstly the I am using the N/C contact for switching on a heater but it seems the kit when powered up does not switch on and change to the normally open contact as the heater just stays on and gets hot.
When I use the N/O contact the heater is off all the time
All components seem to be correctly installed.
Can anyone help me???
Probably, you’ve made the same mistake twice.
Check orientation of the IC and diodes. Check if you get 12VDC between pins 4 and 11. Short two outer pins of T1, relay should click and led should light. If not, check continuity of PCB tracks.
Hi
I bought three of these kits, took my time and soldered them all the same way but can only get two working.
Have checked both the diodes and IC abd are all working well
Can you offer a little more detail on finding voltage between pins 4 and 11?
I’m new to this and can’t find anyway on identifying these pins through the instuctions or board itself.??
Thanks
Zander
Hold the IC so that you can read the type #.
Pin 1 is now in the lower left hand corner. Pin 7 is in the lower right hand corner. Pin 8 is opposite to pin 7 and pin 14 is in the upper left hand corner.