WG K7000, I see SPARKS!

[StonedMason]

1st Post.

Have wanted to build a MAME cab for years now but living on the Isle Of Man (UK) I could never afford to buy the Monitor

Finally someone sold me a TMNT 4 player Cab with a WG k7000

I have read a load of posts on this forum last night to do with monitor problems as after buying the cab i noticed the screen twitchin every 1-2 seconds. Opened the back and could hear a snap sound that was timed into the twitchin on the screen. I could see a small white spark but called it a day and went to bed.

The next day i noticed around the area where the spark was that a resister had a small circular orange disk soldered over the top of it and it was very close to some thing that looked like a transformer. Bent the legs on the orange disk so it was out the way and fired up the cab. Things seemed ok but again the clicking/spark kicked in 

I chucked a cover over me and the cab to find out where the spark was and i found it coming off that large transformer (I think after reading its called "Fly Back") and jumping to the heatsink behind it.

The picture is not mine but i thought i would use it to show the location of the spark.

Im trying my best to learn and understand the electronics of this cab but I cant see how the monitor is earthed. Tried to learn about the isolation transformer but i dont understand how it isolates the live wiring. I will make a quick pic of the wiring as im sure its not right... i heard the isolation trans whatever has to be earthed and its not ?!?!

Sorry i realise i have just stated my problems and not pointed out why im posting 

Do you think the sparks would happen if the monitor was earthed ? like if something was building up and then just jumping/zappin to another component but if earthed this would not happen?

My dads got a analog multi meter. If its not a earth problem and not a fault with the fly back thing where should i focus the multi meter on ? I dont like the idea of discharging the monitor or probing about to much while everything is live but if i had to do you know where to test and what readings i should be gettin?

Sorry for my english but since school i just struggled. Always wanted to build a cab after finding MAME and ROMS. Just my lack of knowlege with the monitor

[qrz]

could be an poorly grounded core  ( see foil side of pcb )
or , it may be the beginnings of insulation breakdown on the flyback.
in that event, it would be best to replace the fly .


in a pinch, a generous application of silicone rubber may seal it..
although , it may then arc at a diff location   



qrz

[StonedMason]

I cant see any earth running to the monitor at all unless the jamma psu is giving earth to the jamma board and then to the monitor ? dont know if thats how it works. Would it be safe to earth the monitor myself by taking a wire to it ?

Plus could you look at my wire pic i made and let me know if i should earth the Isolation transformer at all ?

Im itchin to try a few things but i get the feeling its not wired up write as i can see this cab was chopped up abit... plus its got turtles in time jamma in it and not the original turtles  still a kick ass game

can someone point me in the write direction for a new flyback, can you still buy stuff like that? Going off the stickers on the tube it was made Aug 31 89. The atraction of that cab was the monitor... would brake my heart to see it dumped just for a fault 

Cheers for your help qrz

[Kevin Mullins]

As for the grounding of the ISO and the monitor -
You can run a wire from the "green" wire to the metal casing (screw terminal, etc) of the ISO and the same on the monitor chassis. Same as the way they probably have the marquee, control panel and coin door.

But your sparking is most likely a hairline crack developing in the flyback like qrz was referring to. Common problem, common part..... just want to make sure which model of the K7000 you have before ordering. (K7197, etc) You may also find a WG part number on the flyback itself something like 053X0528-001.

http://www.therealbobroberts.net/parts.html#flyback
K7000 flyback replacement (053X0528-001)    $19.00

[StonedMason]

Cheers kev.

I have earthed the monitor chassis now with a wire but not the ISO yet as it has 2 pins on the input L N and 3 pins on the output side L N E. I would have thought the earth would have been on the input side where the walls power and earth come in... thought maybe it was wired up back to front but i doubt that 

Could not find anything on the flyback apart from

mnRain

30AM
8x04   (The 8 could have been a 6 but im sticking with 8 )

There is a large Wells Gardner sticker on the chassis of the monitor with the below info

Model No. 25k7183
120v 60hz 100w Max

So im guessing the model is a 7183 ?

Going to have a look at that site now and see what i can find. Thank you for helping me understand what needs replacing, i will let you know what happens once I lean how to discharge the screen and replace the flyback

 

[SirPeale]

It's a good bet that's a K7183, yes.  Let's see a picture.  Especially of the flyback.

[StonedMason]

Sorry for digging up this post and not adding pictures but i finished my Cab now.

I managed to get a flyback, gave up trying bob roberts as he never replied to any of my emails It was smaller but the pins/legs of the flyback were the same as the old one. I connected everything back up and fired it up. No picture and a large amount of noise (fuzzin, fizzing) was coming from the flyback. turned it off and on again a few times thinking it was about to blow up but the noise over a few mins time died down and i hoped that the 2 nobs on the flyback would bring me a picture. They did  thanks for your help

New problem. I have noticed while settin up mamewah that my screen starts to show little white dots randomly around the screen. Its as if the picture being drawn by the crt is just ramdomly blasting a few white pixels. this is not a constant problem but lately its happened twice and i turn off the monitor incase i need to adjust anything. Anyone know what this could be or let us in on the possible area i should test?!?!

I also have lines running vert on the left hand side of the screen. They look like water marks... not solid. They are heavy on the far left and then fade away coming to the centre of the screen.

Oh.... The flybacks "SCREEN" nob. Should i turn the "BRIGHTNESS" and "CONTRAST" to the max on the chassy and then slowly turn the SCREEN up so its a lil too bright? Then cut the overly bright screen down with the BRIGHTNESS and CONTRAST controls on the chassy ?

Never replaced a flyback before sorry guys

Thanks for your help and i will post pics once my rents get back home. They should be back tomoz about 10pm so i will nab the camera off them and show you what the picture actually looks like

[Kevin Mullins]

Oh.... The flybacks "SCREEN" nob. Should i turn the "BRIGHTNESS" and "CONTRAST" to the max on the chassy and then slowly turn the SCREEN up so its a lil too bright? Then cut the overly bright screen down with the BRIGHTNESS and CONTRAST controls on the chassy ?

I generally start with the Contrast and Brightness about midpoint.

UNPLUG the video input so that all you have is a black screen.
Now adjust the SCREEN on the flyback just until it starts to whiten the screen, then turn it back down a tad until you just get a nice black screen.

Now plug your video input back in and adjust your Contrast and Brightness to suit.

It's all in the eyes of the adjuster. 

[StonedMason]

Thanks Kevin 

Everyone I know thinks im a ass for adjusting the brightness on their TVs/LCDs/CRTs as most my friends seem to have the "brightness" set so high that the blacks are actually gray!

I see you like a nice black too