The scope is a 465M, S/N is B056721 but it looks like that may not be original, assemblies have been swapped etc..
The problem: the scope had been working fine until one day the crt was dead. Fuse F558 was blown, (it goes from the 32V unreg to the HV oscillator circuit). All other supplies are fine.
I first unsoldered pin 10 from T550 (feeds the 3x multiplier), but the
95V supply still wouldn't come up. I then checked Q556 & Q552, the transistors driving T550, both are fine. I then checked the caps and transistors in the 95V circuit, all fine. I then unhooked the jumper leading from L582 to the rest of the scope, still no luck. I then took out the crt (both the plug on the back and the anode lead), and the supply came up with no problems. 94.5V, .07A, negligible ripple.My readings are as follows. Anode off & Rear Plug off: 94.5V @ .070A Anode on & Rear Plug off: 64.2V @ .54A & climbing Anode off & Rear Plug on: 26.7V @ .427A & climbing Anode on & Rear Plug on: 21.6V @ .460A & climbing
Is this probably a bad tube? I don't have a whole lot of experience with scopes, as this post would indicate, and don't want to get a new crt if it's not going to fix it.
Also, just to make sure, there isn't any alignment procedure when swapping scope crt's, is there? I don't figure there is, just want to make sure.
I have another 465m, but the same fuse is blown, and I haven't gotten into it yet.
All thoughts appreciated.
Thanks, Steve