On 13 May 2007 04:13:57 GMT, Jim Yanik wrote:

Steve wrote in
:

On Sat, 12 May 2007 18:16:45 GMT, Steve wrote:

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
snip
BTW,the 465M was a "ruggedized" scope to use in lieu of a regular 465,but
NOT the same circuitry,being more similar to a 455A2B2.

My experience was that they were not as rugged as a regular 465,the plastic
case/chassis flexed and caused problems.

I've seen so many of them on ebay listed as the "ruggedized" version
of the 465b. I guess because they look similar on the front panel the
must be the same inside, right? (sarcasm)