TIme for an update .. and to ask for some advice from more experienced peoples.
So I got all power supplies back running smooth after the dreaded short that messed up things. I almost replaced all components on the 5 and -15 volt supplies - everything is in spec .. I have 49.999 flipping to 50.000 V on the 50 V rail with sub 2mV ripple. Yeah I replaced all old opamps with new ones, transistors .. all dead caps etc. Power supply section is ironed out now no more death after X minutes. Yet I have no CRT turning ON yet
So I debugged and digged out all I could in the HV supply and Z-Axis circuits. Remember .. I had to sit on the lower voltage side as I don't have a HV probe to stick my fingers in the -2.5Kv and 15Kv areas.
So far I am sure that the HV oscillator works; I tested all caps, diodes and transistors all OK; voltage measurements and waveforms match the service manual very close. The thing is "humming" at a nice 51.2 ish Khz. I am almost 100% that this area works.
The -2450V supply is also looking good - not measured but I took all HV diodes out , caps measured , other diodes measured all checks OK. Again I did not measured the -2450V supply. HV diodes are fine , tested with a power supply they are not shorted and they both open somewhere between 9-10V. Also I am sure that the wingdings on the HV transformer are not shorted because I can see waveform from the output winding (there is one that gets out @ about 140V) that is used for Z-Axis and waveform matches closely what the service manual says. Like I said I am not 100% here because I cannot measure the actual -2450V.
Z-axis, measured and confirmed all working. Again i tested every single bit of part except resistors, measured voltages and waveforms. Everything by the book there.
At this stage I am thinking that the HV multiplier circuit - the 15KV one - is gone. I can hear a typical CRT "turn on" buzz and when I turn it off I can see the two neon bulbs flashing for a split second. CRT still does not turns on .. not even a spot or faint trace coming on the screen.
But like I said, I am not a master in this so some experienced advice wold be welcome. I wonder if there is anything more I can fiddle with on the low voltage side? any idea wold be welcome. If not .. I am going to borrow a HV probe from somewhere to measure thing.