what is needed to switch CRT to LCD

jcterzin

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Hey guys. I have an LCD monitor that I rarely use anymore for an older pc. Since my CRT in my arcade is not working and I dont want to electrocute myself, I was thinking I would switch it out for the LCD. I googled this but came up with only blathering on about how its 'blasphemy' for switching. Could be true, but I just want the damn thing to have a picture, so I figured Id just start a quick thread.

What do you need in order to swap out a CRT for an LCD?

I figure a signal converter that goes from CGA to VGA but what else?
 
First, you need a signal converter, because the arcade monitor uses 15.75khz video signals, and a PC VGA monitor uses 31.75khz VGA. Then you need some kind of bracket to hold the LCD monitor in place. After you get it working, then you'll want to stare into the sun for a good long time, to damage your vision badly enough that you won't notice just how incredibly terrible the LCD monitor looks in the game.

Much better option is to repair your existing monitor (or have it repaired).

-Ian
 
aww man, I feel like I was just slapped. Im just trying to get ANY sort of picture! The monitor in there now isnt working for one reason or another and it seems to be a lost art for repair. I have the LCD monitor on hand which means a cheap repair if I can get it installed. How much worse could the picture really be? Oh, and do I need to pick up any wiring harnesses?
 
do you know why LCDs look like garbage?

try looking at the picture quality in MAME, when you have scanline simulation disabled, or play it cloned on a PC monitor and on TV out on a CRT TV and observe all the jagged edges in the picture on the PC monitor that aren't hidden by the scanlines on the CRT TV.

also factor that a lot of LCDs will stretch the picture.

now you know why it's "blasphemy".

now tell these helpful people what your monitor is and what the problem is.
 
aww man, I feel like I was just slapped. Im just trying to get ANY sort of picture!

Hehe. Sorry - not trying to make fun of you or anything, just stating the truth. :D

The monitor in there now isnt working for one reason or another and it seems to be a lost art for repair.

It's not a lost art at all. Many of us, including myself, repair our own monitors. If you post what kind of monitor you have, and what it's doing, we can tell you how to fix it. If, for example, it's an Electrohome G07, I can tell you right now you probably need a flyback, horizontal output transistor, fuse, and about twenty electrolytic capacitors. Total parts cost, around $35.

If you don't want to repair your monitor yourself, you can send the chassis out to get rebuilt to either a forum member, or perhaps Chad at ArcadeCup.com - he specializes in repairing arcade monitors for people.

I have the LCD monitor on hand which means a cheap repair if I can get it installed. How much worse could the picture really be? Oh, and do I need to pick up any wiring harnesses?

The problem is, that it's more than just a wiring harness. You need an intelligent scan converter box - a frame doubler - in order to display a stable image at twice the frequency. That means that the entire frame needs to be stored in some kind of memory. Such a converter will not be cheap. Fixing the arcade monitor would be cheaper and easier.

And yes, the picture will be pretty bad. For one thing, LCD monitors can't do a very good black. Similarly, LCD's look best only at their native resolution - and the resolution of an arcade game is so low that it will look fuzzy on the LCD.

-Ian
 
Alright Alright, Ill look into repairing it. Man, I hope I don't electrocute myself!

From ArcadeCup.com, I believe the board to be a Wells Gardner K7301 / 7300. The problem is that I get no picture. It plays blind. Now, Ive never seen the glow of a monitor neck before, but I dont see anything in the neck so Im assuming there is none. The board gets the 110v it needs but still, no picture.
 
The 7300 is a fairly new monitor. I've actually never worked on one of those before. But I know many others here have.

In any event, it would probably be about the same cost to send your monitor chassis to Chad to get repaired than it would to buy a video converter. To display an arcade game on a VGA type monitor, you'd need something like this: http://www.ambery.com/rgbcgatovgac.html Problem is, that device costs $92.00, and then you'd still need a PC monitor, video cable, etc. And it won't work as well as a real arcade monitor.

Or, for $105.00, you can send your chassis to Chad to be rebuilt.

-Ian
 
Oh, and for reference, neck glow is a dull orange glow coming from the filament of the picture tube - it'll be right in the elements visible inside the clear glass neck of the tube. For reference, look at another (working) arcade monitor, or you can pull the back off your television or computer monitor and look at it. Sometimes it can be tough to see if the room is brightly lit - turn off the lights and look.

The filament is generally powered by a winding in the flyback. So, if the monitor is "dead", and something has caused the fuse to blow, or there is a component failure in the flyback driving circuit (say, blown HOT, caps, etc), then you won't get neck glow. Similarly, anything in the monitor's power supply failing will cause the B+ to go into shutdown, and you won't get any neck glow either.

-Ian
 
or in the case of my K7171, some sort of short in the heater circuit will make the CRT shut off. lol

blasted cold solder!
 
You can use one of these adapters. I have one and it's pretty good. It's best to learn how to fix your own monitor though if you can find the time. If you're not a mechanically inclined person then weigh your options and do what works best for you.
 
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I have no idea how to check which component may be busted or not. Like, how do I test the flyback? Can I use a multimeter on it? I know the voltage should be high, but if I take it off, discharge it, and then use the multimeter is there a way to see if it is the problem?
 
well, I'm not an electronics wizard. when it comes down to something like this, I'd send it out for repair.

but here's what's going on here. you got AC going in, and the monitor's not powering on. usually, in the worst case scenario, you have to start checking diodes and such. I'd check the HOT (high output transistor) ... if that's dead, then that would certainly cause your problem. I think most will agree though that HOTs don't just die... something else usually goes bad that takes those out. diodes, in particular. diodes are supposed to keep voltage from going to places it doesn't belong. :)

there's symptoms of a flyback going bad. particularly if it takes a long time for the monitor to warm up, or if it loses focus a lot. if it arcs at all (like crackling sparks and such :)) or if the flyback casing is physically cracked, then it's probably no good.

the good news is, WG monitors are cheap to fix. they're cheap to fix if you know what you're doing though, which.. well, you don't. I don't either.

may I suggest www.arcadecup.com.

do you know how to remove the anode and discharge the monitor right? or solder?
 
ive watched alot of tuts on how to discharge the anode. I just tried it and didnt hear a 'snap' like most say they do. I tried it again and nothing. At this point im assuming its discharged, and I just took the board out. On another post, DustyBri suggested a post that said what may be happening.

Originally Posted by Rrcade
I looked at the following from Ken's page:
Common problems: Power applied, Monitor dead, No neck glow.
Cause: Resistor R812, Transistor Q801, and Capacitor C807 are all bad and should be all replaced.
Solution: Replace R812 (68 ohms, 1/2 watt), Q801 (2SC2073 or 2SD478 or NTE 375), and C807 (100 uf @ 16 volts).

so im going to try and do these first, and see what happens. If nothing then I guess ill ship it off to arcadecup.
 
alright solid news. I did look over those components and at least one, the resistor is fried. Im going to head to radio shack and try to find a replacement, ill keep you guys updated. cross your fingers.
 
ok, so radio shack had the capacitor and resistor that I needed to replace. I took out a transistor as well but really have no idea how those work in general. The guy there told me that the one he gave me 'should' work. What does that mean? Can a transistor be 'kinda' the one you need?
 
Well, i installed the 3 busted components and still nothing. Same damn thing. Looks like im going to have to send the damn thing out to chad. I hate monitors.
 
ok, so radio shack had the capacitor and resistor that I needed to replace. I took out a transistor as well but really have no idea how those work in general. The guy there told me that the one he gave me 'should' work. What does that mean? Can a transistor be 'kinda' the one you need?
Transistors need to be the same part number.

I'm a monitor noob but if the monitor doesn't turn on what you have to do is check the fuses for continuity or at least to see if they're blown. If the fuse is blown then your hot, voltage regulator, flyback, capacitors or diodes might be bad. You can buy a rebuild kit from Bob Roberts and this should replace most of the common culprits.

After replacing the bad components you can check the diodes on your board and voltage regulator to make sure those aren't bad.

Is the fuse blown? You might also try adding your location to your profile. This way if there is someone local to you they might be willing to lend you a hand.
 
Ill add my location. I didnt realize it wasnt on there. I took out the board again today, but this time instead of meddling with it, I just packed it up and sent it out to Chad at Arcadecup.com. Im willing to work on things, but not when they have near lethal amounts of energy stored up in them. Some things you just have to pass on.
 
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