Neon based capacitor leakage tester

[ppppenguin]

I think I've got this right. The 100n across the neon doesn't need to be 630V. The neon strikes at no more than 150V, probably under 90V, so a 250V capacitor will be fine. The neon and 100n could equally be in series with the pair of 1M resistors rather than the -ve of the HT.  If you are certain that the voltage rating of your resistors is greater than the applied HT then a single 2M2 resistor can replace the pair of 1M.