Chris
What are you using to ( equipment wise ) to measure the voltages?
that click momentarily?
If the supply voltages are spot on ..time to move on the horizontal
Amp
Dave
ArtekManuals
On 1/17/2013 8:36 AM, chrismh_somenumber wrote:
?
Update...
First, can someone explain this statement to me, from the
note between steps C-5 and C-6 on page 4-9 of the service
manual: "Look for a power supply where the burst voltage
is very low in relation to the specified supply voltage".
I'm not sure what I'm looking for there.
I have been working my way through the power supply
maintenance section. I checked the resistances at the test
points specified on page 4-9. They are all OK. The
voltages at those test points are spot-on.
I moved on the the Rectifier board. I scoped all three of
the test points given and they looked OK. I did notice
that test point 3 near the I Sense Port (pin 13) of U1275
was about half the amplitude of the waveform given in the
service manual. The shape is similar. The waveform also
seemed very noisy and it was difficult to get a stable
trigger.
The voltages on the rectifier board were in the ballpark
of those given in the service manual with the exception of
the 7.5V at pin 6 of U1274. It was about 6.8v. No idea if
that indicates a problem.
One other interesting thing I noticed was that probing the
108V test point caused a clicking on the inverter board.
It sounds like the power supply is going into pulse mode,
but only for a second. Coincident with the clicking, the
neon lamp on the inverter board flickered, and the neon
lamp on the Z-axis board briefly flashed on and off.
Unless someone notices something here that is seriously
out of whack, I'll be moving on to the horizontal
amplifier board.
All input is appreciated,
Chris
--- In TekScopes@...,
"chrismh_somenumber" wrote:
>
> My recently acquired 7104 has a problem, which I
assume is something to do with the horizontal amplifier
(please feel free to correct me...).
>
> When the scope starts up, I get a normal trace for
about 3-5 minutes, then it changes to a compressed
vertical line. It appears that the vertical is working
since I can make the vertical line grow and shrink
(vertically) by varying the v/div or by varying the input
signal. However, the entire trace, and the readout, is
compressed to a single vertical line.
>
> Thoughts?
>
> Thanks,
> Chris
>
--
Dave Henderson
Manuals@...
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Welch,MN 55089
651-269-4265
