Hi Bob and Dan-I'm still here

[Cindy]

Okay, I couldn't post or read messages since yesterday. I
kept getting an error message when I tried to post, and
when I tried to read, all I got was "message unavailable".

So, what does all the vertical and horizontal information
mean? Do you recommend that I lower the refresh rate?
Because I will if that's what it takes. I may have put
the pieces together in this computer, but I'm not sure
what all the specs mean. I do have the box checked that
says do not show unsupported whatevers, because it may
cause permanent damage, so I thought that when it showed
alot of options, that they must all be supported. Help,
I'm confused.

 

[Cindy Mericle]

Update - it's 1:00 am here, and I'm going to sleep. I
will be back tomorrow, look forward to hearing from you.

 

[Bob I]

Basically your CRT is displayed in the same manner that a typewriter
would create a page of text. It sweeps from one side to the other and
then drops down one pixel and then "paints"(causes the phosphor bits to
glow) the next line, until it has done all the "lines" and then starts
over at the top. Lets say you have set 1024x768 at 70 Hz as the
resolution and refresh. The electron beam will swing back and forth 768
times to paintone screen and it will do this 70 times in on second. This
beam is aimed with electomagnetic coils on the neck of the CRT.

So, horizontal is the "sweep" rate or how fast the electron beam is
pulled from side to side to "paint" the screen.(no you don't adjust
that, at least not directly)

And, vertical is how fast it gets from the top to the bottom to complete
the screen painting so is called the "refresh" rate.(this you adjust)

Now if you have the "refresh" rate at the "high" end of the range and
the monitor is marginal then you may see interesting things like
"tearing" or "screen folding" and other weird visual effects BUT it
should be constant, not once in awhile. If you run the refresh rate
really low, then the "screen" can "fade" between rescans and so the
"interlaced" scan method is used to paint every other line so your eye
doesn't pick up the "blinking". There is also the "60 cycle" flicker
which is caused by the screen being at the same frequency as the
lighting and tend to be more pronounced with fluorescent lighting(Adjust
the refresh to something other than 60 Hz if you are getting this.)

All of these visual effects are continuos and don't "come and go". If
you get "shimmering", you probably have something creating a "pulsing"
or varying magnetic field like speakers or an electric motor interfering
with the "coils" attempts to aim the electron beam. Moving suspect items
around the CRT(or the CRT itself) should change the "shimmering", or
cure it. A pattern of cause and effect will lead you to the answer. For
the most part any "random problem" can be tracked down by observing what
else happens at the same time as the problem occurs.

 

[Cindy Mericle]

Thank you very much for the explanation! Did you get my
reply on the long thread about the degauss? The fact that
it does not replicate the "shimmering"? Good word choice,
by the way. And that I will not pop that button ever
again. Also, I moved everything I could think of that
might have a magnetic effect on the monitor, and low and
behold . . . . no shimmer for days now. You have saved me
the price of a new monitor at this time and I am very
grateful. Dan, you also have been a huge help. I want to
thank everyone who was kind enough to take the time to
offer their help.

One last question, if I want to keep the setting at
1024x768, at 85 Hz, is this an okay setting for this
monitor? Because that is where I like it, and it's so
great not to have the shimmer thing going on. And how
much or how little does it take to have a magnetic
effect? Could something as small as the cheap computer
speakers do it? Will a small incandescent lamp do it? I
will make sure I keep everything as far away as possible
from now on. Thank you very, very much. I'm shimmer free!

 

[Dan Seur]

Hi Cindy - great news! Looks like Bob pinned the problem & I'm glad it
seems to have gone away.

I believe most monitors these days go through an automatic degauss cycle
when you power on; you may notice a 'thunk' and/or some 'crackling' as
the guns & magnets come alive. The degauss gets rid of any magnetic
fields inside the tube that may have built up and which can slightly
deflect the 3 beams from their intended pixel targets, causing color
aberrations. When you see unusual color splotches on a blank white
screen it's time for a manual degauss. Should be quite rare.

You could also try moving things back close to the monitor one at a time
to see if some particular item causes that bad symptom. One of those
objects might have a wiring problem or some such.

The frequency specs I pasted earlier from your monitor's manufacturer
indicate that the monitor responds to a max refresh rate of 72Hz, if I
recall correctly, so at 85Hz you're overdriving the device, but if the
screen isn't distorted in any way you've lucked out. I have no idea
whether over time this might have some bad effect on the electronics of
the device - but a quick email to the manufacturer's tech support squad
might put that concern to bed for you. In the meanwhile, I guess you
might as well enjoy the gallop! And thanks for posting back...

 

[Wolf Kirchmeir]

Thank you very much for the explanation! Did you get my
reply on the long thread about the degauss? The fact that
it does not replicate the "shimmering"? ...snip....

I've followed this interesting thread, and also want to thank those who
diagnosed the problem correctly and arrived at a solution. I don't have
Cindy's problem, but it's always good to increase one's knowledge base!

BTW, Cindy, cheap computer speakers are often not shielded, and could very
well affect the monitor if located too close to it.

 

[Bob I]

If the info below is your model monitor then the specs indicate the
monitor can go as high as 120 Hz for the refresh rate.( the V Freq.) So
the 85 is ok. You may be limited by the garaphics card if "120" does not
show as available. As far what items will cause "interference", it will
be determined by the amount of current (magnetic field size), shielding
in the monitor (and the object it the case of computer speakers)
distance from the monitor, and where it is placed adjecent to the
monitor(side front, side back how close it is to the coils). Hope this
helps.

Model: V771
Max Resolution: 1280 x 1024
Sync Type: Seperate
H Freq/ V Freq: 30-72 Khz / 50-120 Hz
Monitor Type: Multi-Frequency
Tube Size: 17
Connector: HD-15

 

[Dan Seur]

Very nice of you to say so, Wolf - and I believe it was Bob I
who got to the heart of the problem. And corrected at least 2
of my misreadings of Cindy's monitor's specs, for which I'm grateful too.

 

[Bob I]

Thanks for credit, but we are all in here helping!