I’ve just completed the first of 2 nixie clock kits.
I plugged the first one in once complete and the display lit up briefly and then disappeared. The voltage between VR1 and the cathode of D6 is now just 17V, when previously it was 180V.
I have completed the main board for the second kit I bought. Voltage between VR1 and D6 is showing 180V. When I swap the IC from the broken board into the working board, the voltage drops to 17V. However, swapping the IC from the normally functioning board into the not working one generates a voltage of over 400V between VR1 and the cathode of D6.
If we understand correctly, you have one fully functional board.
We suspect two problems on the other board.
Most likely there is a problem with the feedback from the HT supply.
Check the values of R7 and R13.
Make sure R7/R13 node is connected to pin 4 of microcontroller.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.
We also suspect damage to the microcontroller.
If this is the case, return controller for inspection/repair: