Very strange ! I don't really know what to suggest to you on this. I think trying to fix the brightness has to be a priority simply because its a fault that should be able to be sussed out. The usual way of changing brightness is by altering the cathode potential relative to the grid/s (or vice versa).
Lol, you're not the only one to fix things in your sleep
Lol, you're not the only one to fix things in your sleep
Ive gone over and over this scope checking components,checking for cracks in the PCB,things plugged in backwards,etc...etc.. and I cant find anything wrong? I think it might be the calibration is way out because the calibration directions are just as bad as the schematic? Ive tried to adjust the intensity according to the book,it says to adjust VR1021 until the trace disappears. The only trouble is it doesn't disappear? The circuit has all the right voltages etc... I can turn the VR1021 from side to side as well as the intensity pot and nothing happens,this is weird because if the circuit wasn't working I wouldn't have a trace in the first place would it? I'm getting -1700v on the test point using the DBT.I tried plugging into the mains again but it arced at the neon lights area this time? This would have to be the most frustrating repair Ive ever come across.Oh well Ill just have to sleep on it again.Ha!
OK Ive slept on it Ha! I think the intensity pot has been pushed in and damaged in the post because when it was delivered the power input and corner stand were smashed on the back of it so its probably busted on the front as well. Ill pull the face off it today and change the pot if its damaged?
I took the intensity pot out and measured it at 7.9k,its not damaged although its supposed to be 10k ohms, 7.9k should be OK don't you think? Theres two things Ive got to follow up,the intensity pot and the VR1021 pot that's supposed to dim the trace line, its not working,Ive pulled that and it reads OK as well? Ill continue to check out the circuits involved because its always something simple. Most of the time anyway.Ha! I was measuring the high voltages when I put the probe on the D1012 cathode,it didn't arc but an eery pretty blue light appeared at the tip,I could hear a slight buzzing noise as well?
7.9k is a long way off tbh, I know pots have a poor tolerance but that's getting a bit to far from where it should be. I doubt it would cause an issue though.
You just have to work on the brightness fault, that has got to be a way in to all this.
The blue glow is normal when probing high voltages... you should try it on a PL509 valve used as a line output transformer driver on old TV's
You just have to work on the brightness fault, that has got to be a way in to all this.
The blue glow is normal when probing high voltages... you should try it on a PL509 valve used as a line output transformer driver on old TV's
7.9k is a long way off tbh, I know pots have a poor tolerance but that's getting a bit to far from where it should be. I doubt it would cause an issue though.
You just have to work on the brightness fault, that has got to be a way in to all this.
The blue glow is normal when probing high voltages... you should try it on a PL509 valve used as a line output transformer driver on old TV's
Yes,Ill keep at it and get back to you when I find something Mooly.
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