--- In TekScopes@...,
"rwdplz1" wrote:
>
> OK, I checked C4419, it is a 5000uF 35V
capacitor. ESR is 0.08, which should be about right. However, after
desoldering it from the board (which is a real pain with the two large
mounting legs), and measuring capacitance, one of my meters couldn't measure
it, and the other read 0.185 nano Farads. Both of these meters read the
capacitance of other small capacitors I have on hand perfectly, so the meters
are fine. ESR of the other large capacitors is about the same, but I'd rather
not desolder them from the board if I don't have to, to prevent damage to the
fragile traces.
>
> --- In TekScopes@..., "Tom
Miller" wrote:
> >
> > OK, good. I would think the next
thing to check is C-4419, a 5000 uF can capacitor.
> >
> >
Regards,
> > Tom
> >
> > ----- Original Message
-----
> > From: rwdplz1
> > To: TekScopes@...
> > Sent: Tuesday, January 15, 2013 2:40 AM
> > Subject:
[TekScopes] Re: 465B Oscilloscope No -8V
> >
> >
>
>
> > 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
> > > >
>
> >
> >
>
