[volt-nuts] 3420B chopper drive problem

[Dr. Frank]

Hello Dave,

in the schematic, the polarity of the diodes in series with the neon 
bulbs is definitely wrong.

If you compare with the 3420A on page 7-7 (29), but also with the Fluke 
845 which is similar, both neons have to be switched at 180°.

Maybe someone else has erroneously reversed one of the diodes in your 
unit before?

If both neons are really firing in phase, instead, that could explain 
this non-symmetric waveform, which you observe.

Frank