19-05-2021, 06:34 PM
The aquadag and acetone are on order without any issues.
I have done a bit more playing
as I now have potential replacement tubes for the set. I decided to run the test setup on the Ferguson tube for a while, something I was reticent to do for any period of time before in case i completely knackered it and certainly not at these voltage levels g1 to cathode, previously tests were at lower voltages. But over time there was a gradual improvement of emission to the stage now were the diode potential has dropped to 25 volts and the current risen to 0.9 mA and when running the TV as normal it is showing a marked improvement, so much so it is showing that the TV needs an expert touch to it, someone better than me at it.
I suspected that the IF stages had been played with prior to me coming along, I had an attempt at sorting it following the manuals but I do have ringing on the verticals, i still have distortion bottom right of the screen which at one time was put down to the tube effect of static build up as it slowly fades over time, but I am also wondering if the scan coils have a bit of an issue.
I still see faint flyback lines when on the test card.
I plan to change the tube over for one of the others, so this will give me a opportunity to clean up one of the spare tubes, re-apply aquadag etc. Have a look at the scan coils and check if I see any signs of green verdigris in them or signs warn varnish/shorting turns. Taking the tube out will give me space to fettle one of the chewed up tuning slugs ends.
It will keep me occupied for a while.
Adrian
I have done a bit more playing
as I now have potential replacement tubes for the set. I decided to run the test setup on the Ferguson tube for a while, something I was reticent to do for any period of time before in case i completely knackered it and certainly not at these voltage levels g1 to cathode, previously tests were at lower voltages. But over time there was a gradual improvement of emission to the stage now were the diode potential has dropped to 25 volts and the current risen to 0.9 mA and when running the TV as normal it is showing a marked improvement, so much so it is showing that the TV needs an expert touch to it, someone better than me at it.I suspected that the IF stages had been played with prior to me coming along, I had an attempt at sorting it following the manuals but I do have ringing on the verticals, i still have distortion bottom right of the screen which at one time was put down to the tube effect of static build up as it slowly fades over time, but I am also wondering if the scan coils have a bit of an issue.
I still see faint flyback lines when on the test card.
I plan to change the tube over for one of the others, so this will give me a opportunity to clean up one of the spare tubes, re-apply aquadag etc. Have a look at the scan coils and check if I see any signs of green verdigris in them or signs warn varnish/shorting turns. Taking the tube out will give me space to fettle one of the chewed up tuning slugs ends.
It will keep me occupied for a while.
Adrian
Learning as I go!
Youtube EF91 Valve
Youtube EF91 Valve
