Nice HP multimeter for the price BTW
Thanks, I really want to get a more modern DMM maybe 87V or something, but this one isn't too bad
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Mianchen, I have noted that you have a shiny new Rigol from the 'multimeter thread'. Perhaps you could use that to look at the waveforms around the Iwastsu HV oscillator Primary and the opamp output to see if there is something sensible happening!. (make sure you use the x10 probe of course!, to reduce loading and to watch out for the 70v rail on the transformer and the switching transistor).
I was busy playing with the Rigol last week didn't have a chance to look at the Iwatsu
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So I probed the oscillator opamp output pin one, all I have was noise (so I believe), please see pic 1.
Probing pin 1 and pin 2 of the HV transformer gave me some interesting waveforms (pic 2 and 3).
I think the opamp oscillator is not working at all? I have swapped the opamp with a few new 4558Ds, everything remained the same. These 4558Ds were actually working in the oscillator test circuit I built on a breadboard - so the IC can be ruled out?
I re-measured all power rails in the 'scope, all spot on except the +70V rail read ~65-66V.
I don't really have much of a clue what to do next :<
One thing I have found was that C46 in the schematic is missing on the PCB...