[Herald1360]

'Fraid I wasn't that organised. I suspected power supply issues but I didn't want to 'scope anything since the circuit is non-isolated- there's a normal transformer for the 5V side AC, but the DC 0V rail is tied to mains neutral to enable the Nixie HT to come straight from half wave rectified mains. A bit odd but cheaper I suppose.


I just pulled the capacitors and checked their ESRs. A quick prod round the rest of the PSU bits showed no obvious faulty bits and two new caps fitted later, it worked. It's on soak now.