The resistance between the -8V test point and ground (either a test point
labeled ground on the board or the scope case) is 49.7 ohms.
I replaced
one tantalum, C4203, 33uF, with no effect.
--- In TekScopes@...,
"pdxareaid" wrote:
>
> you might want to check for shorted
tantalum caps in -8 circuits.
> see:
>
>
phil
>
>
>
> --- In TekScopes@...,
"rwdplz1" wrote:
> >
> > Hello, I am trying to fix my
Tektronix 465B Oscilloscope. I have the service manual and have been using it
to try and figure out what's wrong. When turned on, there is nothing on the
screen, even when pressing and holding beam finder, and the power light
doesn't come on. The only control that seems to work is scale illumination,
which makes the screen glow orange when turned up.
> >
> >
I checked the voltages at the test points on the main board A4 as described on
page 4-24, and found all of them to be within spec: +55, +15, +5, and +110,
EXCEPT for the -8, which measures 0.2mV. The power supply wiring diagram at
the back of the manual shows two blue wires from the transformer, going
through a fuse F4501 (desoldered and removed from board, it's good), then
through a rectifier bridge CR4411, which is also good.
> >
>
> So where do I go from here? What voltage should I be seeing at the two
blue wires, because I'm starting to suspect that part of the transformer?
Thank you
> >
>
