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So the exhausted neon bulbs causes the control grid voltage to be too high, is that correct?
What should I do?
Try to open the sealed/potted board and replace the ZA1004? But the manual states:
It's probably fully potted, so nearly impossible.
Build a duplicate board from schematic (inside a...
I adjusted the grid bias R547 with 1MΩ between cathode and grid and made the fading from left to right disappear, as well as changing the minimum intensity point on the front panel.
Measured 413V. Is it too high? (The ZA1004 have an ignition voltage of 90V and extinction of 80V)
Tried to connect a 1MΩ between cathode and grid and it works, the grid voltage is -45V when looking at 2khz calibration signal:
[Animated image] The waveform wobbles (maybe a PSU ripple), but everything works fine.
The wave seems to fade out, is it normal?
Measured the -2kV output and it's...
Horizontal and vertical deflection seems to be OK, the horizontal voltages vary and vertical is at 20V (which is mentioned correct in the Service Manual).
Unfortunately, I can't measure the voltage across the R564 as I turn R547 yet. But it doesn't change the control grid voltage, when I turn...
That part of the circuit looks partly potted around a plastic case over it. I will have to pry it open somehow, hopefully it's not fully potted.
Thank you for the step in the right direction, highly appreciate it!
I bough a used, nonworking oscilloscope Phillips PM3260e in attempt to fix it.
The symptom: there is no trace. Only when powering down it shows a disappearing beam on the CRT. (Maybe a leaky capacitor?)
First I checked the PSU, found few faulty capacitors with my ESR meter, replaced them. Now...
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