21 inch CRTs and sharpness.
21 inch CRTs and sharpness.
Got a quick Q about big CRTs. I just picked up a 21 inch Phillips and I noticed the picture is sharper around the edges than in the center. It does this at any resolution any color depth. Is this normal of bigger CRTs? Or is something FUBAR? Overall the picture isn't 100% sharp, kinda slightly hazy but only in windows, you don't notice it in games or in movies.
Thanks
Thanks
- Krom
- DBB Database Master
- Posts: 16138
- Joined: Sun Nov 29, 1998 3:01 am
- Location: Camping the energy center. BTW, did you know you can have up to 100 characters in this location box?
- Contact:
Focus. I had to adjust both my NEC 930SB monitors. With CRTs there are a couple pots near the back left of the monitor on the inside, adjust them with a small screw driver till the monitor has a more uniform sharpness. Beware, the pots are very touchy, a small movement will blur the entire screen, you want to use some sort of test pattern a screen full of 8 point text will do the job.
Most monitors have three pots in the back, two are focus (horiz/vert) and the other one is power, if the monitor brightness is where you want it _do not_ touch the power screw. They are as touchy as the focus screws and can turn your screen totally white or black instantly, then it takes forever to tweak the monitor back to the proper brightness.
You might have to take the cover off the monitor to do this, and it has to be done with the monitor on. Be extremely careful, theres 10-20kvolts inside the case and even if the monitor is off they still hold a charge. Do not touch anything other then the screws you want to turn. Both of my NEC monitors have holes in the side of the case so you can adjust the focus without taking the covers off, check and see if the 21" has the same.
Most monitors have three pots in the back, two are focus (horiz/vert) and the other one is power, if the monitor brightness is where you want it _do not_ touch the power screw. They are as touchy as the focus screws and can turn your screen totally white or black instantly, then it takes forever to tweak the monitor back to the proper brightness.
You might have to take the cover off the monitor to do this, and it has to be done with the monitor on. Be extremely careful, theres 10-20kvolts inside the case and even if the monitor is off they still hold a charge. Do not touch anything other then the screws you want to turn. Both of my NEC monitors have holes in the side of the case so you can adjust the focus without taking the covers off, check and see if the 21" has the same.
- WarAdvocat
- DBB Defender
- Posts: 3035
- Joined: Sun Jun 23, 2002 2:01 am
- Location: Fort Lauderdale, FL USA
- WarAdvocat
- DBB Defender
- Posts: 3035
- Joined: Sun Jun 23, 2002 2:01 am
- Location: Fort Lauderdale, FL USA
im never opening a CRT based device again in my life.
i had a bad experience with CRT's.
*i think ive already laid this incident out on here, but its been awhile so here it is again*
i had a small 3' B/W dual power tv that my mom had in the basement in the junk box. so i grabbed it out of the box and took it upstairs out to the garage. i opened up the case and started getting curious as to what parts did what. well i noticed this large black suction cup attached to the side of the tube with a much larger wire leading back to the flyback transformer. i grabbed a flathead screw driver and started to pry that cup off.............................
ZZZZZZZZZZZAAAAAAAAAAAAAP!!!!!!!!!!!!!!!!!!!!!!!
i was blinded by what could be described as "The holy white light" for about 30 seconds.... after i regained my sight, i smelled burning metal, plastic and fiberglass. i looked at the smoldering screwdriver in my hands only to discover that the metal itself had vaporized about halfway up the shaft and was slowly melting the plastic handle. of which at that same moment, it got hot in my hands so i dropped the handle.
i grabbed some heavy duty rubber gloves and promptly tossed the tv into the trash.
i had a bad experience with CRT's.
*i think ive already laid this incident out on here, but its been awhile so here it is again*
i had a small 3' B/W dual power tv that my mom had in the basement in the junk box. so i grabbed it out of the box and took it upstairs out to the garage. i opened up the case and started getting curious as to what parts did what. well i noticed this large black suction cup attached to the side of the tube with a much larger wire leading back to the flyback transformer. i grabbed a flathead screw driver and started to pry that cup off.............................
ZZZZZZZZZZZAAAAAAAAAAAAAP!!!!!!!!!!!!!!!!!!!!!!!
i was blinded by what could be described as "The holy white light" for about 30 seconds.... after i regained my sight, i smelled burning metal, plastic and fiberglass. i looked at the smoldering screwdriver in my hands only to discover that the metal itself had vaporized about halfway up the shaft and was slowly melting the plastic handle. of which at that same moment, it got hot in my hands so i dropped the handle.
i grabbed some heavy duty rubber gloves and promptly tossed the tv into the trash.
The experience ACE reflect the warnings issued when it comes to opening and messing around the inside of TV's.
It seems that the coils that drive the tube hold somewhere around 50,000 volts or more or something like that.
The warnings used to tell one to beware of replacing parts in a TV unless the capacitors that delivered the voltage to the tube were properly discharged.
If one accidentally shorts the capacitor or any wire connected to the capacitor... you basically got a instant lesson in welding. Like ACE did.
So if you remove the cover from your CRT be careful where you poke around
It seems that the coils that drive the tube hold somewhere around 50,000 volts or more or something like that.
The warnings used to tell one to beware of replacing parts in a TV unless the capacitors that delivered the voltage to the tube were properly discharged.
If one accidentally shorts the capacitor or any wire connected to the capacitor... you basically got a instant lesson in welding. Like ACE did.
So if you remove the cover from your CRT be careful where you poke around
-
- Defender of the Night
- Posts: 13477
- Joined: Thu Nov 05, 1998 12:01 pm
- Location: Olathe, KS
- Contact:
15,000VAC for black and white and 30,000VAC for color.REDDER wrote:It seems that the coils that drive the tube hold somewhere around 50,000 volts or more or something like that.
No kidding. Ace is lucky he's still alive. DAMN lucky. Though this would explain why he was so angry when he first showed up.If one accidentally shorts the capacitor or any wire connected to the capacitor... you basically got a instant lesson in welding. Like ACE did.
And don't be a dummy! (ACE) If you don't know what you're doing or what you're mucking with, leave it alone. At the very least have someone that knows TV repair nearby so they can tell you what you can and can't touch. Matter of fact, its a good idea to have a second or third person nearby just incase you do get a lesson in what tens of thousands of volts really feels like.So if you remove the cover from your CRT be careful where you poke around
I got 2 used NEC tv's...same make and model. Took both of them to a local t.v. repair place and for 80.00 they swapped parts and tuned up one of the sets so it works great (had it 2 years now). So why would I want to fiddle in the back of of a killer voltage trap when for 80.00 a pro will do all the work.
REDDER wrote: The warnings used to tell one to beware of replacing parts in a TV unless the capacitors that delivered the voltage to the tube were properly discharged.
one would think that 3 years of sitting in a box with absolutely no power supplied in those 3 years, would be enough for those capacitors to discharge themselves?!?!?!
If one accidentally shorts the capacitor or any wire connected to the capacitor... you basically got a instant lesson in welding. Like ACE did.
SHADDUP!!!!No kidding. Ace is lucky he's still alive. DAMN lucky. Though this would explain why he was so angry when he first showed up.
-
- Defender of the Night
- Posts: 13477
- Joined: Thu Nov 05, 1998 12:01 pm
- Location: Olathe, KS
- Contact:
Ace, let me put it to you this way. I had in my possession a flashlight that had no battery. It used Lens' Law to generate power. (magnet moving through a coil of copper wire, thus generating a current charging a capacitor which lit up the light) I didn't even fully charge the sucker, maybe half power, and the damn thing stayed on all night long and still had enough power to light the LED. Even if theres nothing to discharge the capacitor relatively quickly (like an LED), the energy bleed-of would be so minimal that it would take several years like Krom mentioned. It all depends on two factors: How large the capacitor is and how much charge has been placed on it. I've personally seen 10µF (thats micro-Farad or 10x10^-6 Farad) capacitors hold a full charge for over a month. Thats a very small capacitor compared to the larger ones you'd find on a CRT monitor motherboard. I think you get the picture.AceCombat wrote:really?!?! oooookay.
hey krom, got any ideas on the topic i just made?