465M blows internal .25A fuse


Bloy2004
 

I have a 465M scope and after a while the display went dead.
Examining the internals revealed the 1/4A fuse was blown and
continues to blow after replacement. I have a manual, but nothing
is said about causes for this fuse blowing. Without the fuse in
place, I get +55VDC from the power supply Cap side (+32VDC
unregulated), and +.5VDC from the HV transformer side (pin 4 of part
T550). Where there should be +95VDC, I get only 11.4 VDC.
Questions:
1.What are the most likely causes for this fuse blowing, when all
was working fine.
2.What are the poosible causes for the +95Vdc to be way low.


Any responses welcome...


markh893 <markh@...>
 

Hopefully, this will work. I can't seem to get anybody to help me
with the posting
problem.

I have the same problem. Does your manual include the schematic?
You shouldn't
see more than 32V on the 32V line. Fix that first. Could be a bad PS
cap. You
shouldn't be getting anything on the +95V line, as that comes from
the PS run by the
32V line. I've heard that the tripler goes bad. I'm still waiting to
hear what values I
should expect to use to make my own.

- Mark