@Papa Smurf :
OK so now I understand PSU is fine and debugging is starting...
This huge fuzzy blob rather looks like low PDA voltage and/or focus problem, no ?!
At any rate, if I were in your shoes and I WILL be in your shoes as I have two 547 to restore... before wasting any time on random parts of the scope, I would first make sure that the CRT subsystem is indeed fine.. I would want to see a sharp fine bright dot on the CRT... if so then yeah I would know for sure that the problem has nothing to do with the HV and I would proceed to the amplifiers and plug-in.
So, to rule out any CRT subsystem issue, quick and easy test to do :
- At the CRT itself, disconnect the 4 wires that go to the H and V deflection plates/pins. Short the H pins together and V pins together with alligator clips or whatever. This way the scope is not in control of where the spot might appear (off screen for example), but YOU are. With the deflection plates shorted, spot should appear in the center of the screen. If it does not, and/or is not bright and sharp as it should... then you know you have something to fix in the CRT subsystem before anything else. Once that is all working fine, then yeah I would start investigation the rest of the scope.. but only then.
It's such a quick and easy test to do it's not worth wasting time chasing red herrings not doing it !
FWIW of course !