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revving up first time since 2006 (dim screen)

 
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timbreana



Joined: 24 Jun 2010
Posts: 3
Location: Urbana, Illinois

PostPosted: Sun Jul 04, 2010 2:33 pm    Post subject: revving up first time since 2006 (dim screen) Reply with quote

After transferring most of my files to my iMac running OSX, I turned my NeXT off in 2006. The main reason was that the screen had become too dim to use without a lot of eye strain. However, I've discovered some WriteNow files that I need to convert to RTF, and I can only do that on the NeXT. To fix the dim screen problem I've got brighten it up by messing with some controls in the back of the display.

Has anyone out there had any experience with this procedure?

Jim Beauchamp
jwbeauch@illinois.edu
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itomato



Joined: 27 Dec 2005
Posts: 302
Location: Santa Cruz, CA

PostPosted: Wed Jul 07, 2010 2:46 pm    Post subject: Reply with quote

I have performed this procedure with varying results..

Tips:

* Spring for a set of 'Archer' or similar TV tube adjustment tools.
* Have a mirror positioned in front of the display
* Load up a good test pattern (zebrae?)
* Read a bit about 'flyback transformers' beforehand.

From the FAQ:

Quote:

5.23 How to adjust MegaPixel Display brightness and focus?

brightness, MegaPixel focus, MegaPixel

Adjust it using the following information.

From: Charles William Swiger

I have adjusted several monitors with no problems, but make sure you
know what you are doing before opening anything. I expressly disclaim
responsibility for any ill results that may occur.

In order to adjust NeXT's MegaPixel display (called 'the monitor'
hereafter), you'll need (a) the NeXTtool (or a 3mm Allen wrench), (b)
a plastic adjustment tool (preferred) or a thin bladed screwdriver,
and possibly (c) a Phillips-head screwdriver.

(NB: A similar procedure will work for color monitors, but you should
either know what you're doing or you'll probably be better off letting
a pro deal with it.)

Turn off the computer. Disconnect all cables to the monitor. Look at
the back of the monitor. There will be 4 screws there; use the
NeXTtool (or Allen wrench) to remove them. Remove the plastic back of
the monitor and put it out of your way.

Reconnect the cables and turn the computer back on. As the machine
powers up, examine the back of the monitor. You'll see a metallic box
(usually silver, though some are black) surrounding the monitor's
vitals. This protects you against the dangerous voltages inside, and
also insulates the monitor from electromagnetic noise. On the back of
this box are several holes for performing adjustments. There are two
focus controls (labeled 'focus' and 'dynamic focus'), a brightness
control (labeled 'brightness' or possibly 'black level') and several
others that adjust various things like screen size and position.

Depending on the exact placement of the controls on the circuit board
of your specific monitor, some of these controls may be difficult (or
impossible) to adjust from the back. If this is the case, I will
describe what's necessary below. Otherwise, adjust the appropriate
controls using either an adjustment tool or a screwdriver. Be warned
that a screwdriver probably will cause some interesting video effects
when it enters the case. Ignore this the best you can, or find a
plastic adjustment tool, which is what you *really* should be using
anyway. Using a flashlight will help you see into the hole so that you
can align the business end of the tool correctly.

Focus and position controls are fairly obvious. Adjust them slowly
until you're happy with the results. Don't muck with anything you
don't need to; the factory settings are usually pretty decent.

To correctly adjust the brightness, follow this procedure: Turn the
brightness of the monitor all the way down using the keyboard. Adjust
the brightness control on the back of the monitor until a barely
noticeable picture forms. Then turn the brightness down a little so
this picture disappears completely. Check that you can get adequate
brightness by using the keyboard to brighten the screen. If the
display isn't bright enough, adjust the brightness control on the rear
of the monitor high enough so that the monitor display is adequate.
Note that you won't be able to dim the screen completely from the
keyboard...sorry.

Once you're finished, shut down the computer, take off the cables,
reattach the back of the monitor, and reconnect the cables. You're
done.

If the control you need to adjust proves to be difficult, you may need
to enter the metal case. This happened on one monitor's focus control
and another's brightness.

WARNING: THE VOLTAGES INSIDE THE MONITOR'S CASE ARE VERY DANGEROUS,
EVEN WHEN THE MONITOR IS OFF. BE VERY CAREFUL, OR YOU CAN SERIOUSLY
INJURE OR EVEN KILL YOURSELF.

DO NOT PERFORM THE NEXT INSTRUCTIONS UNLESS YOU ARE CONFIDENT THAT YOU
KNOW WHAT YOU ARE DOING. You'll have to power off the computer again,
and disconnect the cables.

Looking at the monitor from the back, notice a section of metallic
shielding on the right side of the metal box that extends to the
picture tube. This is where the flyback transformer is connected. It
shields a wire that is charged to about 25,000 V.

WARNING: DO NOT TOUCH THIS WIRE, IT CAN SHOCK YOU THROUGH ITS
INSULATION.

Being very careful of this, remove the metal case by unscrewing the
Philip's head screws that hold the case on. Don't touch the screws
that hold the picture tube into the front of the monitor's case.

Once you've gotten the metal box off, reconnect the cables. Figure out
what control you're going to adjust, and make sure that you can do so
without touching anything else inside. Again, *watch out* for the wire
that connects to the picture tube on the right side.

Power up the computer. I recommend that you use only one hand to make
the adjustment, and that your other hand be placed in your pocket (or
similar equivalent, if you're wearing clothes lacking pockets). This
precaution reduces the chances that you'll make a short circuit
between one hand, your heart, and the other hand --- a good idea.

Perform the necessary adjustment(s), being very careful not to touch
anything inside. Then shut down and reassemble the monitor, following
the directions given above.

Hopefully, these instructions will prove useful. Once again, please be
very careful...I don't want your death and/or injury on my conscience
(or a lawsuit, for that matter, either Smile

_________________
-itomato
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timbreana



Joined: 24 Jun 2010
Posts: 3
Location: Urbana, Illinois

PostPosted: Fri Jul 23, 2010 4:46 pm    Post subject: Re: revving up first time since 2006 (dim screen) Reply with quote

Well, the machine came up OK after being dormant for 4 years. I forgot my user login but remembered the root and then was able to reset my user. I also was able do a LAN file transfer, so everything was cool except for the dim screen.

Thanks for the instructions. I had kept a copy but it was nice to see them in a good font.

Today I finally got around to taking the back cover off of the Megapixel. I think from the instructions there must be two types of Megapixel displays: 1) Has easy-to-adjust brightness control; 2) Has hard-to-adjust brightness control. I did this adjustment on some other NeXT displays in 1993 and it was a piece of cake. However, after I take the back cover off this one all I see for controls is:

H CENT
H HOLD

V HEIGHT
V LIN CUTOFF

DYN FOCUS FOCUS
V CENT WIDTH

Unfortunately, there is no brightness control, so I must have a No. 2.

So it looks like I would have to disassemble the display further by removing the metal case. It doesn't look easy!

I'm getting together with another guy tomorrow, so we'll see what happens. It's kind of looking like we'll have to skip the brightening operation, and I'll have to convert and save my files with the dim screen. Right now, it's barely tolerable and I hope it doesn't get any worse.

If anyone has any recommendations, particularly about something I might have missed based on what described above, I am all ears.

Thanks,
Jim
jwbeauch@illinois.edu
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timbreana



Joined: 24 Jun 2010
Posts: 3
Location: Urbana, Illinois

PostPosted: Sun Jul 25, 2010 8:26 am    Post subject: Re: revving up first time since 2006 (dim screen) Reply with quote

Well, my friend and I got together and worked on brightening the Megapixel screen. As I mentioned in my previous message, the labels on the back of the display (after removing the case) were somewhat ambiguous. My friend brought a plastic TV adjustment screwdriver and identified "CUTOFF" to be the brightness control. However, after considerable fiddling around we were only able to achieve a slight improvement in the overall brightness. Beyond this point it would tend to wash out the black areas, thus decreasing the contrast. Maybe one of the other controls would control the black aspect, but we didn't get that far.

Anyway, it's useable when I turn the lights off and I'm having a good time converting WriteNow and Appsoft Draw files to RTF and PS and transferring them to my iMac via our ethernet LAN.

Cheers,

Jim
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