S
Steve
- Jan 1, 1970
- 0
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
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