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Author Topic: CRT only showing green  (Read 2957 times)

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error-

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CRT only showing green
« on: February 01, 2014, 06:05:36 am »
I recently bought a Arcade Machine.
First time I start it up, the whole display is just green.
So I tweak around the colour settings to a point where it looks semi normal.
The next day I start up the machine again it's back to plain green.
Also, the screen is old and has severe screen burn.

My question is will degaussing the screen fix it or is it a capacitor / resistor that's faulty?

Should I rather buy a new screen to replace it?

Any help or advice will be greatly appreciated.

Here's a video of the problem:


dcninja

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Re: CRT only showing green
« Reply #1 on: February 01, 2014, 09:36:14 am »
put a tv in and mame it! advice done! boom! jk i honestly don't know that much about crt repair. something is obviously wrong and needs repairing.

error-

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Re: CRT only showing green
« Reply #2 on: February 01, 2014, 10:16:05 am »
I tested it now again.
I left it on and after about 10 minutes most of the colour comes back to normal.
But the colours are still not what they need to be. No purples and hardly any blue.

mgb

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Re: CRT only showing green
« Reply #3 on: February 01, 2014, 09:19:38 pm »
A cap kit may not fix your particular issue but its an easy enough repair to do anyway so why not.
Besides that there may be an issue with the color transistors on the neck board.
You should get a schematic on the monitor and figure out which transistor is for which color and try swapping them to see if another color is effected.
There's also the possibility of cold solder joints. This is very common on old monitors.
It's good practice to re flow the solder on as many solder joints as you can, especially the solder points under larger heavier parts and connectors.
Also verify the rgb connections from the game board.
 Make sure they are seated well at the monitor.
While either having someone watch the monitor or with a mirror setup, jiggle the connections.
Of course be careful with your hands in the powered on monitor.
If you have to pull the boards for repair, make sure you know how to priperly dust gargle the tube before pulling the anode cap.

Another option to look at is pulling the connection at the game board and clean the connection and reseat.

So to sum up, I would
1) Verify and clean connections between the game board and monitor.
Pull and clean game board connections

2) reflow solder joints. During reflow, make sure to hit the transistors on neck board.

3) cap kit, never a bad idea even though its the most prescribed thing to do but it often clears up alot.

4) replace color transistors

The last step would be to get the tube checked out.
I'm gonna assume you don't have the tools to diagnose and fix the tube so this would be only if nothing on the chassis board is found to be the case

Good luck

buffett

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Re: CRT only showing green
« Reply #4 on: February 02, 2014, 05:29:56 pm »
you should post pics of your chassis.

this will help in repairing the chassis.

you may have a chassis and tube issue.

there is no reason to blindly replace parts that are not bad.

Peace
Buffett
Come to MAGfest and game in the 24-7 arcade for 4 days. www.magfest.org  And see my collection of 90+ Arcades and growing.
Need your (K7000, 4900, std/med res 13"-25") or Sanyo fixed!!!! pm me.
Visit my website. www.thearcadebuffett.com For Monitor and PCB repairs.
Fully rebuilt chassis ready to ship. Trade'ins welcome
I have met --- Tim McVey --- world nibbler champion and many of you have not.

mgb

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Re: CRT only showing green
« Reply #5 on: February 02, 2014, 06:11:01 pm »
Just to be clear, I wasn't telling him to blindly replace parts.
  That's why I say, first make sure all connections are clean and secure.
Then reflow solder joints because bad solder joints are very common and simple to repair.

As far as a cap kit goes. Yes it's the most generic advise given for every little problem and often times not what will fix the problem at hand. But if a monitor that's 20-30 years has never been recapped, it's a simple worthwhile repair to make regardless.

But yes you are right
Pics of the chassis board should be posted so that its known what monitor you have.

buffett

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Re: CRT only showing green
« Reply #6 on: February 03, 2014, 12:43:53 am »
Just to be clear, I wasn't telling him to blindly replace parts.

never said you did.

it is general advice i give to many people.

we are all here to help so lets help the op get his game fixed.

pics of the chassis are needed.

Peace
Buffett
Come to MAGfest and game in the 24-7 arcade for 4 days. www.magfest.org  And see my collection of 90+ Arcades and growing.
Need your (K7000, 4900, std/med res 13"-25") or Sanyo fixed!!!! pm me.
Visit my website. www.thearcadebuffett.com For Monitor and PCB repairs.
Fully rebuilt chassis ready to ship. Trade'ins welcome
I have met --- Tim McVey --- world nibbler champion and many of you have not.

error-

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Re: CRT only showing green
« Reply #7 on: February 03, 2014, 01:48:17 am »
Thanks a lot for the help and advice so far.

I'll take some pictures tonight after work.
That will only be in another 9 hours or so.

I'll try and be as thorough as possible.

error-

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Re: CRT only showing green
« Reply #8 on: February 03, 2014, 04:09:57 pm »
I might as well give some back story.
I was under the impression that there weren't any original Midway cabinets in South Africa, until I found this machine on Gumtree.
It was too far away for me to go have a look at it, so I had to put a lot of faith in the seller.
I couldn't let this machine fall into the cracks of such a small arcade market, never to be seen again.
It's so rare in this country that I even started building a MK replica, because I was sure it'll be impossible for me to ever get my hands on an original.
I bought the Killer Instinct machine for $660.
The screen was working fine until it was shipped roughly 900 miles to my house.
The guy sent me pics of the screen on with decent colours.
Unwrapped it and when I saw started up the machine, the screen was all green.
I tweaked the colour settings at the back of the screen a bit and until it was a bit better. But still lacking most of the blue colour.
Turned off the machine, and next day the screen was green again until I let it warm up a bit.
I suspect that while it was being shipped to me it had a few knocks and might have damaged some connections.
I'm completely unfamiliar with the inner workings of a TV, so I'm being cautious with touching anything.
Here's some pics of the machine.


















mgb

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Re: CRT only showing green
« Reply #9 on: February 03, 2014, 05:19:07 pm »
Looks to be a Wei ya 825 chassis board.
It may very well not be too old so you may not need a cap kit.

Definitely go through and check connections of cables at monitor and game board first.

Plus I just noticed tape on your yoke wires.
Go though and look at all the wires going to the monitor. The Wei ya boards are typically for replacement of bad chassis boards. This machine probably had a wells Gardner and they swapped the monitor chassis board out.
They may just cut wires and spliced in new without solder or wire nuts or anything and then taped.
I see it all the time.
« Last Edit: February 03, 2014, 05:25:21 pm by mgb »

buffett

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Re: CRT only showing green
« Reply #10 on: February 03, 2014, 06:37:28 pm »
that is a Hantarex POLO frame.

if a cap kit does not fix it you will need to get your tube checked.

Peace
Buffett
Come to MAGfest and game in the 24-7 arcade for 4 days. www.magfest.org  And see my collection of 90+ Arcades and growing.
Need your (K7000, 4900, std/med res 13"-25") or Sanyo fixed!!!! pm me.
Visit my website. www.thearcadebuffett.com For Monitor and PCB repairs.
Fully rebuilt chassis ready to ship. Trade'ins welcome
I have met --- Tim McVey --- world nibbler champion and many of you have not.

mgb

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Re: CRT only showing green
« Reply #11 on: February 03, 2014, 07:36:10 pm »
The frame is from a Hantarex Polo but the chassis board has been replaced with a Wei-Ya 825

ed12

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Re: CRT only showing green
« Reply #12 on: February 03, 2014, 07:39:31 pm »
well i would look at the rgb/ground/sync input plug
it look's like g and b are comming right out

ed
Shipping something from the U.S. to Canada for repair/exchange?  Please use USPS to avoid (additional?/excessive?) shipping charges.  PM me if you have any questions.

error-

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Re: CRT only showing green
« Reply #13 on: February 04, 2014, 03:35:16 pm »
mgb, you're a life saver.

After work today, I opened up the machine. Cleaned and wiggled all of the connections.
And ta da, worked like a charm.
I'm now just sitting with some positioning problems..

The horizontal plane is too wide. I can't seem to get it narrower.
I might need to adjust the colour settings a bit more, but it's a bit hard walking back and forth while tweaking the settings.
I'll just wait 'till some buddies come over.




error-

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Re: CRT only showing green
« Reply #14 on: February 04, 2014, 03:40:57 pm »
To think that such a basic thing can fix the colour. :notworthy:
Atleast I know what to do if anything ever happens to any tv in my cabs.
Thanks guys for the help.

mgb

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Re: CRT only showing green
« Reply #15 on: February 04, 2014, 04:32:58 pm »
Glad to hear it worked out well. If there is a pot for adjusting this and it's just not going small enough
There is a horizontal width coil on that board that will bring the width in.
It is the gold coil with white top and bottom. Its behind the purple capacitor in one of your pics.
This has a hex adjustable core in the middle. But if you try adjusting it with a metal hex key, you will get burnt.

I suggest you do a google search on CRT horizontal width coil adjustment or something.
Also this part is easy to break so be careful.