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Author Topic: How to Test a CRT Monitor?  (Read 2773 times)

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Brian B

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How to Test a CRT Monitor?
« on: February 10, 2011, 10:43:21 pm »
I've acquired a mostly empty cab with a monitor and although I was told it works I really want to see how it looks.  I pulled the back off and there are a few parts that I'm not sure how to connect.

I was told the monitor works on a transformer and that is on the bottom left.  There is a junction box that takes in a standard IEC cord in the middle.  There are 3 cables coming from the monitor chassis (that I assume are for the power).  Also there is a small ribbon cable that appears to be the signal input (with 5 connections that are R,G,B and ? H/V?)

How do I get a signal to these easily to test?

Any suggestions that would help me identify the monitor (I was told it was Tri-mode but would like to confirm), and let me know the best way to get a signal to it to check the picture?

There are adjustment controls wired on the front side of the panel (that I didn't take a picture of) and that's what a big bundle of wires goes to (not pictured).

Lastly, there is a ground wire that is unconnected and doesn't seem to reach the monitor.  Would it have been connected to the control panel?  Can I just clip it or hide it away?

If more information is needed on my end I will be happy to get it.

Thanks!

lilshawn

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Re: How to Test a CRT Monitor?
« Reply #1 on: February 10, 2011, 11:56:23 pm »
if you could get a pic of the electronics of the monitor it will be much help. the barcode info is simply a tube #, it has no bearing on the rest of the monitor.

if that monitor is a tri mode, you likely won't need that transformer in the bottom, but don't get all rippy yet, some monitors REQUIRE a transformer to operate without frying in .5 seconds.

you are correct regarding the wires, RGBHV and the power.

the ground is likely leftovers... if you like you can tuck it out of the way, or use it in your project, or cut it off if it's to ugly for you. it's up to you. i would use it to ground a computer case.. but that's just me.

buuuut, until we can verify the monitor's capabilities i wont outline a test procedure just yet. you can end up doing more harm than good.

Brian B

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Re: How to Test a CRT Monitor?
« Reply #2 on: February 13, 2011, 05:26:37 pm »
Thanks for the offer to help.  Here are some more pictures.  Due to the top of the cabinet being in the way the best I can do is a mirror or sticking the camera inside and snapping away.  There is a board to the side of the main board and a single main board (not including the board attached to the back of the gun).

Let me know what else you might need and sorry for the quality.  The main board says "Neotec" on the underside.

lilshawn

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Re: How to Test a CRT Monitor?
« Reply #3 on: February 13, 2011, 06:07:32 pm »
if indeed it is tri-mode like you say, then it's probably an NT500DXB7 if not, then it's a NT2700 series (NT2700 cga / NT2701 ega / NT2702 vga)

in any instance it's a neotec and has a SMPS power supply. (no isolation transformer needed)

you should have a standard VGA connector possibly on the backside by the neck card, or even a cable wired onto the neck card. it may have been modified though.

if indeed this is the nt500, you can simply set a windows computer/laptop to 640x480 or 800x600 and plug it into the monitor.

the 2700 series will need some creativity to get a picture, but it's not impossible.


Kevin Mullins

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Re: How to Test a CRT Monitor?
« Reply #4 on: February 13, 2011, 07:38:41 pm »
 ;D
Not a technician . . . . just a DIY'er.

lilshawn

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Re: How to Test a CRT Monitor?
« Reply #5 on: February 14, 2011, 01:43:08 am »
ya, i don't get pics on my cellphone...so your post of only a smiley kinda confused me  :lol

NT2701  (NT-27ER) -  is an EGA (medium) resolution monitor.

the 27ER is an early chassis that was replaced with the 2701

kinda like the u2000/k7400

this is not a tri-mode then.
« Last Edit: February 14, 2011, 01:51:02 am by lilshawn »

Brian B

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Re: How to Test a CRT Monitor?
« Reply #6 on: February 14, 2011, 03:41:36 am »
Ok, thanks--I knew you guys could figure it out.  So what resolutions can I run the monitor at?  I was planning on getting an ArcadeVGA card.  How would I set it up?

So I don't need the transformer, correct?  Do I just cut the plug off the end of the green/white/black wire (out of the monitor) and connect to the bottom box where the AC interface is?

How do I check the picture (and interface with that tiny RGB plug)...or are you still suggesting that there is another connector somewhere else?

Also, assuming it works well enough...is it cost effective to upgrade the chassis to allow for higher resolutions or is the tube itself somehow limited?

Thanks again for everyone's patience and help!

Brian
« Last Edit: February 14, 2011, 03:44:25 am by Brian B »

lilshawn

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Re: How to Test a CRT Monitor?
« Reply #7 on: February 14, 2011, 04:30:53 pm »
Quote
Ok, thanks--I knew you guys could figure it out.  So what resolutions can I run the monitor at?  I was planning on getting an ArcadeVGA card.  How would I set it up?

that is one possibility. another is using the software program called soft15k... it will force your card to display lower resolutions so you can patch directly to the monitor. the arcade VGA is a card that has been modified to pretty much do the same thing... so 6 to one half dozen to another.

Quote
So I don't need the transformer, correct?  Do I just cut the plug off the end of the green/white/black wire (out of the monitor) and connect to the bottom box where the AC interface is?

i personally would place a power bar/ surge suppressor in the bottom of the cabinet... you can never be too careful with surges. monitors are particularly temperamental when it comes to power. but yes, if you like you can wire it directly.

Quote
Also, assuming it works well enough...is it cost effective to upgrade the chassis to allow for higher resolutions or is the tube itself somehow limited?

yes, and no. the problem is that that even though the 2700 chassis and the 500dx chassis use the identical tube, the yokes are different. the yoke is the coils of wire up on the tube that deflect the beam of electrons across the screen. the yoke is designed to run at 25khz. if you try to run it at VGA (which is 31khz) the yoke can't handle it. it will burn up. there is ways around it, such as replacing the yoke, but for what all the stuff would cost, you might as well buy another monitor.

Quote
How do I check the picture (and interface with that tiny RGB plug)...or are you still suggesting that there is another connector somewhere else?

there is a connector on the neck board that will accept a plug... the picture you took earlier with the yellow wires... the other end of that is probably attached to the plug... the photo with the yellow wires does not look like the plug that is supposed to be on the neck card, so it should still be attached. IE: you should have 3 sets of wire bundles going to the neck card, as well as a thicker red and a thicker white wire, and 2 smaller black wires for ground. one of those bundles is going to be your video wires.

there is a page over at ultimarc that kind of explains how to hook up an arcade monitor to the VGA port on the computer.  including the pinouts for the red blue green and syncs.
http://www.ultimarc.com/monfaq.html

the biggest part on your side is you have to get your computer to output the proper 25khz frequency first. that's where soft15k comes into play.
http://community.arcadeinfo.de/showthread.php?t=8170

Brian B

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Re: How to Test a CRT Monitor?
« Reply #8 on: February 16, 2011, 11:47:15 pm »
Quote
Ok, thanks--I knew you guys could figure it out.  So what resolutions can I run the monitor at?  I was planning on getting an ArcadeVGA card.  How would I set it up?

that is one possibility. another is using the software program called soft15k... it will force your card to display lower resolutions so you can patch directly to the monitor. the arcade VGA is a card that has been modified to pretty much do the same thing... so 6 to one half dozen to another.

I read the information on the soft15k program and since I have a Radeon 9600pro card that I was planning on using it looks like I'm good.  I assume I select the "install for 25kHz" option for this monitor I have?

Quote
So I don't need the transformer, correct?  Do I just cut the plug off the end of the green/white/black wire (out of the monitor) and connect to the bottom box where the AC interface is?

i personally would place a power bar/ surge suppressor in the bottom of the cabinet... you can never be too careful with surges. monitors are particularly temperamental when it comes to power. but yes, if you like you can wire it directly.

I was planning to use a power strip with surge suppression.  I would like to use the male version of the plug that I snapped a picture of earlier to wire in the power cord for easy removal.  Where can I get one or how can I get the wires out of one I have that is too short?  Or, would it be better to just cut the plug off and use wirenuts or something similar?

Quote
How do I check the picture (and interface with that tiny RGB plug)...or are you still suggesting that there is another connector somewhere else?

there is a connector on the neck board that will accept a plug... the picture you took earlier with the yellow wires... the other end of that is probably attached to the plug... the photo with the yellow wires does not look like the plug that is supposed to be on the neck card, so it should still be attached. IE: you should have 3 sets of wire bundles going to the neck card, as well as a thicker red and a thicker white wire, and 2 smaller black wires for ground. one of those bundles is going to be your video wires.

I have attached another picture of the other end of the yellow wiring.  Is there some sort of VGA cable with this plug on the other end?  Or, do I have to remove the cables and then buy a raw VGA plug and insert them into it?  Or...?

Quote
there is a page over at ultimarc that kind of explains how to hook up an arcade monitor to the VGA port on the computer.  including the pinouts for the red blue green and syncs.
http://www.ultimarc.com/monfaq.html

I read the monitor FAQ at Ultimarc and the part that is worrisome is "25 Khz monitors. If you have a choice, don't go for one of these. They cannot display any of the early games at native resolutions as the scan rate is too high. Only a few games used these monitors and only these few games can be displayed 100% accurately on them. Advanced MAME will be needed for these monitors."

Does this mean that I cannot properly display CGA resolution games on this "medium" resolution monitor and I am restricted to only certain "EGA" resolutions?

So, assuming I can get a cord of some sort to wire into the DB-15 VGA jack of the video card I can get this guy running.

Thanks again!

Brian


lilshawn

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Re: How to Test a CRT Monitor?
« Reply #9 on: February 21, 2011, 01:24:40 pm »
There is a difference between just displaying an image and displaying it in it's "native" resolution. If you just want to utilize the monitor, cool, if your looking to preserve the original look of the original game, then perhaps a different monitor would be better.

If you just want to get an image to play games, then just hack up an old VGA cable and wire it up. As long as you just feed it 25k it will be fine. Trying to display anything else may result in damage to the monitor.

You will have to configure your game/mame/windows/etc. To stay in the 25K resolution and not switch to anything else.

Brian B

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Re: How to Test a CRT Monitor?
« Reply #10 on: February 23, 2011, 08:06:31 pm »
Ok, I understand. 

I got the power wired up so far.

One last question: The wire coming off the chassis has 5 connections (as you can see...r/g/b and wires with a black and white stripe).  I read the Ultimarc tutorial and there are supposed to be 6 connections.  Is the black ground and the white sync?  If yes, do I just tie H+V together on the VGA cable?

If not, then what?

Thanks again,
Brian

lilshawn

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Re: How to Test a CRT Monitor?
« Reply #11 on: February 24, 2011, 10:42:32 am »
Your black stripe should be ground, and just tie the h-sync to the white stripe. You shouldn't need to tie them together, but everyone seems to have differences. You may have to try the v-sync and maybe even both like you say to get an operative picture.

Brian B

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Re: How to Test a CRT Monitor?
« Reply #12 on: April 26, 2011, 09:55:38 pm »
Sorry to revive this thread, but I finally got an adapter to switch the wires to the DB15 plug and connect to the computer.  I tried the white wire in both the H and V sync connections on the video card but all I get is a bright vertical line that follows a click from the chassis down the center and a faded horizontal pattern of red wavy lines.  These alternate about a second or two...click, line, off, background, etc.

I am running at 512 x 384.  Is this correct for this monitor?

Any further help would be much appreciated!

Also, is there any harm in jumpering the H and V connection on the output of the video card to see if this works or do I run the risk of damaging the card?

Thanks,
Brian

lilshawn

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Re: How to Test a CRT Monitor?
« Reply #13 on: April 27, 2011, 12:18:31 am »
"bright vertical line" is generally not good.

i'm kinda thinking you have something wrong with the deflection circuit. if you can, test the horizontal output transistor (HOT)

Brian B

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Re: How to Test a CRT Monitor?
« Reply #14 on: April 27, 2011, 11:51:54 am »
I'm not a tech...how do I test?  Can you confirm I'm sending the monitor a resolution it can handle?

Thanks,
Brian

Brian B

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Re: How to Test a CRT Monitor?
« Reply #15 on: May 01, 2011, 02:29:49 pm »
Ok.  I think I've given up on this. 

How much ($$) should I advertise it for on the forum in this condition? 

Tube face is perfect and it appears to be in good condition otherwise (w/ or w/o the mounting brackets).  Perhaps I'm still not connecting it properly or it may need a simple fix/adjustment--I don't know.

Whoever buys would have to pickup.  I'm in Los Angeles.

Thanks,
Brian

  
 

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