Thanks, and all around a good bit of advice! Fortunately I'm actually a returning adult student (non-traditional as they say) so I'm going part time and this is my only class. In my years since high school I've learned it's best to stay on top of things so it's not all that bad to get ready for the exam! :)
Chris
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--- In TekScopes@..., Chin Siang Lim <cslim388@...> wrote:
Don't mind me butting in, Chris.
I would strongly suggest that you finish all your exams first and then come
back to spend time on the scope. The scope can wait. To relax your tired
mind after intensive periods of study, the troubleshooting is wonderful for
a short while.
I remember one of my teacher's advice : a divided mind cannot generate full
power. Focus on your studies for now.
Go and get your distinctions and As; am sure yahoo group wanted you to do
well in your studies.
Cslim
On Sunday, February 24, 2013, Chris wrote:
**
I'm apparently unable to convey a clear message today lol.
Lets try this again - I meant to say all voltages came within 0.3V of
their intended values. Cross checking them to the values they should be,
with the +/- allowed range, they all fall easily within range.
And in my last sentence "with the 87v diode for U800 listed " should read
lifted, not listed.
One of those days! (Bouncing between studying for my physics
electrostatics exam and troubleshooting the scope) :)
Thanks for the help!
Chris
--- In TekScopes@... <javascript:_e({}, 'cvml',
'TekScopes%40yahoogroups.com');>, "Chris" wrote:
Oh, yeah the 87v supply comes up to 86.7V I guess I should have been
clearer in my prior message when I said that all the voltages came up to
within 0.03V of their intended values - that was referring to the 87, 42,
15 and 5v lines that were all low (all 9v or under) initially. Lifting
Q1223 brought all the voltages in line, so that prompted the look at U800.
Lifting the diode for U800 brought all voltages up to spec with a "normal"
boot up, minus any horizontal display movements. Since everything came into
spec and it booted with the 87v diode for U800 listed I didn't bother
looking at U950 since U800 seems the apparent issue.
Sorry, hope that clears it up.
Thanks!
Chris
--- In TekScopes@... <javascript:_e({}, 'cvml',
'TekScopes%40yahoogroups.com');>, DaveC wrote:
Chris,
Measure the 87v supply with those doides unsolsered. THAT will tell us
something.
Dave
Sent from my iPhone
On Feb 23, 2013, at 3:26 PM, "Chris" wrote:
As a quick side note - I powered the scope up with the diode
lifted(far side of the diode from U800, easier to desolder and lift), and
pin 7 (the 87v input) of U800 shows -3.98V to -4.00V when the scope is
powered up with the far leg of the diode in the air. Not sure if that tells
you guys anything helpful though.
Chris
--- In TekScopes@... <javascript:_e({}, 'cvml',
'TekScopes%40yahoogroups.com');>, "Chris" wrote:
I lifted the diode CR807 feeding the +87v to the U800 IC and when I
powered it up it booted up just like with I lifted Q1223 from the regulator
board - Looks like it's U800. With U800 the panel controls boot up as
normal, the LED's flash on/off and then onto the set positions. The screen
turns on to a normal intensity, all traces will show up as points and I can
control their vertical positions, but no horizontal traces or horizontal
positions.
With U800's 87v feed disconnected, all of the voltages come up to
within 0.03V of their intended voltages.
So I'm not quite sure where this leaves me yet. Being I don't know
what the internal structure of U800 is, I'm not sure what to look for
outside of U800. I know U800 hasn't been manufactured for years and is only
available as a used and removed component. I read about the re-bake
program, but it would seem mine falls under a different failure method than
the re-bake program can fix. There's some available on e-bay for ~$120.00
shipped from China. Is it worth trying to swap it out with a Chinese
salvaged part? Or is there another supplier of the salvage parts I'm not
aware of?
You guys know these scopes better than I, and your guidance is much
appreciated! I owe a huge thank-you to all of you who have helped me get
this far!
Chris
--- In TekScopes@... <javascript:_e({}, 'cvml',
'TekScopes%40yahoogroups.com');>, "Tom Miller" wrote:
There are two diodes off the +87, one to U800 and one to U950.
Both devices are known to have issues. You might just lift one end of each
diode and see if the 87 volts comes up. That will isolate which device is
causing the problem.
For reference, see diagram 11, power distribution.
Tom
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