WG 25" K7000 issues - AC Voltage 136.0V

[Alaska]

Let me front end that I am new and still learning my way around arcade hardware, but am having a blast so far. Here are my issues.

I have a WG 25K7191 monitor inside of an old "Hit the Ice" cabinet. I tried turning the game on and I get a blip of light in the upper left corner then nothing. It lasts a split second and sounds like the monitor wanted to turn on before it gives up and shuts down. No sound, video, nada. I checked the power supply and have 136.0V coming in and going out to the monitor. The 5V and 12V that go to the JAMMA board are pretty close (4.98 and 12.05). The continuity and solders in the actual JAMMA board look good and I don't see any glaring issues (cold solder joints, dark solder or bulged caps). I'm having trouble wrapping my brain around a few things and was hoping someone could help.

*Don't laugh too hard* What is this main power unit called? [/URL][/img]
***edit*** The picture is of the isolation transformer.

Is the 136.0V output to my monitor too much? What can I do to change this voltage (if needed)?
Is the chassis more than likely the issue and not my power supply or game board?

This is my intention. I just ordered an Arcade VGA card from Ultimarc. I have a PC that I will be hooking up to this cabinet. I would like to bail on the old controls (4-player but only 2 buttons) and go to either 2 or 4-player with 6-buttons. I will more than likely do this with an ipac. What I would like to do before I purchase the ipac, joystick and buttons is to make sure that the monitor works.

Any idea what might be causing the issues for the monitor?

Many Thanks,

~Alaska

[Alaska]

[Alaska]

I disconnected the game board and tried powering on the monitor. Same issue. The rim around the screen flickered, it sounded like it wanted to turn on, then crackled as it shuts down.

The neck of the monitor does not appear to be glowing when the power is turned on.

[grantspain]

136vac is a bit too high,i would think 130vac is a push on this model

you should still get a monitor running at that ac level though,might get regulation issues but it would sort of run

your issue is an actual chassis fault-which could be a multitude of things

[Alaska]

Hmmm... I contacted a few folks about ordering a rebuilt working chassis and am waiting for a response. Do you think if I swap out the chassis that it would remedy the problem?

Also, how do I decrease the 136.0VAC? Is this more of a local issue than a  bad power unit (picture above)

[grantspain]

I have similar issues from my mains supply,i am in the u.k and the supply is meant to be 230vac but mine is 255vac-this means i have to make sure any transformers i use are tapped on the ac input primary as high as possible(i.e 240vac)
if i don't do that all my ac voltages from the transformer are 10 volts higher than they should be-causes issues mainly on electrohome chassis rather than k7000

the k7000 has a regulator ic and i reckon it can soak up a bit of the higher ac

that wiring looks like it could be a midway cab,in that case i think you may find there are ac input primary links that can be moved(its on the big white molex connector i think)-you would need a manual to confirm this
for instance if you find that your ac supply is 130v and the transformer links are tapped to 110v then that would be the problem,you would then move the transformer links to 130vac and i bet your secondary ac would then drop to 120vac

[Alaska]

Thanks for the tip! I'll do some research and see what I can find out.

Can I remove the monitor and frame from the cabinet with discharging? I have been hesitant to do this, but it is really awkward to get inside of the cabinet to discharge the monitor as it sits. My arm would be pretty close to the grounding frame if I tried to discharge it while it is still in the cabinet.

[baritonomarchetto]

After self-shutting down the monitor is dead or turns on then shuts down, turns on shuts down, and so on?

[Alaska]

After self-shutting down the monitor is dead or turns on then shuts down, turns on shuts down, and so on?

So what you're saying is that it's toast?! I need to fully replace the monitor not just the chassis?!

That's a major bummer.

[baritonomarchetto]

No, i am trying to figure out how your chassis could be fixed...

[Alaska]

After self-shutting down the monitor is dead or turns on then shuts down, turns on shuts down, and so on?

When I turn the game on it flickers only around the edge of the screen (split second), then shuts down. Since I purchased it the monitor has never turned on. The guy I bought it from said that he played it a few hundred times, but that it didn't always turn on... and hadn't turned on it awhile.

[Alaska]

The flyback has a hard yellow (almost like hardened glue) goo on one of the adjustment knobs. There are two red wires that attach to the anode. One goes to the flyback control and the other is shown in the above picture. What is that attached to? I noticed that the 25" K7000 chassis for sale on ebay do not have this mounted to them. Is this the isolation transformer?

[Alaska]

Also, there looks to be some darkening on the board in the corner behind the flyback adjustments. I can't tell what caused the darkening. I will discharge the monitor and remove it all from the cabinet this evening to get a better look.

Any thoughts?

[Alaska]

I think I might have found the problem?! ***edit***The chassis needed a new cap kit. The pictures bellow are normal


It looks like someone has messed with this chassis prior to me buying the game. ***edit***See response to this post below. These are factory mods



Some of the caps look to be glued down?! ***edit*** see response below. This is to stabilize caps when pulling a heavy load.

[baritonomarchetto]

Too many questions
Your monitor is in xray protection. It's a zenith k7000 (k7000a) and the block you see is part of the (almost impossible to find) flyback. Not sure what that brown fluid/glue is, but the yellow one under some caps is there to reduce caps movements during charge/discharge cicles.
Extra components under the board are not necessarily a prior op clue: such factory revisions of the boards are common

[grantspain]

yes all that stuff are factory mods,glue is normal btw
probably find it would be quicker/cheaper to find a wg k7000 25" chassis from a forum member or ebay

[jtslade]

Fix it, shotgun it, change the hot, the flyback and cap kit. What AC voltage is the isolation transformer putting out? What does the b+ measure at?


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[jtslade]

Oh and build yourself a discharge tool quick


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[jtslade]

Get magnifying glasses/ headgear (very cheap at harbor freight) and inspect all te solder points on the bottomi of the chassis.

Retouch up solder especially video and power on the chassis.

Really check those IC's on the chassis make sure nothing is bridged or cold soldered.

Get a welder temp adjustable or hakko soldering iron.

Start watching johns arcade videos on capping monitors you tube


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[jtslade]

Use lead solder


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[jtslade]

Triple inspect every cap that you install to make sure that it's the correct voltage and capacitance. More voltage is ok, wrong capacitance ain't. Buy your capkits from Bob Roberts or even better Ian Kellogg 




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[Alaska]

yes all that stuff are factory mods,glue is normal btw
probably find it would be quicker/cheaper to find a wg k7000 25" chassis from a forum member or ebay

Am I able to replace this chassis with a rebuilt chassis that does not have the "block" that is part of the flyback? If anyone has a working chassis for this monitor with new caps and flyback I would be happy to purchase it from them and throw in this chassis if they are interested.

[grantspain]

if you had some experience with monitors i would suggest doing all the things that other members have suggested,but that model uses an oddball flyback-it is available in the u.s but very expensive,by the time you have purchased a decent soldering iron,desolder pump,solder,electrolytic cap kit,horizontal output transistor and maybe a few high voltage polypropylene caps plus that flyback then i bet you would be looking at close to $100.And then of course you need to carry out the work and hope all those items actually repair the problem

i bet a forum member would sell you a good working one cheaper than that

you can use a standard k7000 25" chassis on that tube,actually you can use an incredible amount of chassis on that tube

[Alaska]

Thanks for the help ~grantspain. I'll cruise over to the buy sell trade forum and see if anyone has a rebuilt chassis.

What I gather I that I would need to purchase that specific fly back if I'm going to rebuild my chassis, but I can swap out with a different chassis so long as it is rated for my tube (correct pin configuration as well)?

[Alaska]

Triple inspect every cap that you install to make sure that it's the correct voltage and capacitance. More voltage is ok, wrong capacitance ain't. Buy your capkits from Bob Roberts or even better Ian Kellogg 

Thanks for all the help! i will more than likely swap put chassis with a working one, but will table these repairs until I get the proper tools and some more experience.

I'm going to switch gears and start building a drop in control panel for the cabinet, install the ultimarc VGA card and start working on software.

All, thanks again for all the help!


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[Kevin Mullins]

I would verify that the power going to the monitor is actually isolated before doing anything else.

Unplug the monitor, unplug the machine from the wall.....
Check continuity with a meter between the leads going to the monitor and the plug that goes into the wall.

[Alaska]

I would verify that the power going to the monitor is actually isolated before doing anything else.

Unplug the monitor, unplug the machine from the wall.....
Check continuity with a meter between the leads going to the monitor and the plug that goes into the wall.

I did not get continuity between the prongs on the plug and the adapter that attaches to the monitor. Does this mean that the isolation transformer might have gone bad (see 1st picture above).

[Kevin Mullins]

I did not get continuity between the prongs on the plug and the adapter that attaches to the monitor. Does this mean that the isolation transformer might have gone bad (see 1st picture above).

That is fine, that is what you wanted to see, that means it IS isolated.

 

[menace]

Just FYI--there is a guy on ebay you can ship your board to, to get it repaired..I have had no personal dealings with him but came across the listing while looking for a dead k7000 chassis for parts...maybe someone else can chime in as to whether its worthwhile..

I just typed "k7000" into the search and it came up...

[grantspain]

Just FYI--there is a guy on ebay you can ship your board to, to get it repaired..I have had no personal dealings with him but came across the listing while looking for a dead k7000 chassis for parts...maybe someone else can chime in as to whether its worthwhile..

I just typed "k7000" into the search and it came up...

if it was not a zenith chassis then i would do exactly that but the flybacks for zenith built k7000 are as expensive as buying a recon chassis-that is of course if the flyback is faulty

[Alaska]

Just FYI--there is a guy on ebay you can ship your board to, to get it repaired..I have had no personal dealings with him but came across the listing while looking for a dead k7000 chassis for parts...maybe someone else can chime in as to whether its worthwhile..

I just typed "k7000" into the search and it came up...

I was referred to arcadecup.com by a few folks who had similar chassis issues with various models. The guy is reputable and from what I heard does great work. The turn around time is 3-6 weeks. I'll update this post when I get the chassis back.

[Alaska]

So I finally got the repaired chassis back and I started to reinstall it, but before I turn on the power I need some help figuring out what this ground cable is and where it should be attached?! I reconnected the main (high voltage) ground from the yoke to the monitor ground (visible below) that I had previously clipped to remove the chassis. I do not remember removing this other grounding wire though and do not know where it should be attached. It is bolted to the chassis directly next the k7000a flyback (visible in the picture below and above). Any ideas? Also, it has been 2 months since I sent this off and none of the pictures that I initially took show the orientation of the degauzing plug or video plug (red, green, black, and brown plug, not the plug that goes to the PCB). What are the repercussions for plugging these in backwards? As I said initially... I am not going to plug in the power until I am 100% positive that it is connected properly. Thanks for the help.

[DudeRegular]

My guess is ground to the neck board. Check if you have one attached either via a plastic connector or there is an empty solder point labeled ground on the neck board.

[obcd]

The polarity of the degaussing coil is not important. So, it doesn't matter how you insert that plug.
The video signal connector should be mounted in correctly. You usually have RGB GND and sync.
If you put it in incorrect, you will short one of the color outputs of your game pcb to gnd.
Sometimes, the letters RGB are marked on the pcb, and the wires going to the connector have red, green and blue isolation.
Another thing you can do is find the ground pin with an ohm meter. That one should correspond with the ground of the connector.
The ground pin should measure approx 0 ohm in reference to the chassis which is also ground.

Normally, you have a ground wire going from the wire that runs across the picture tube to the neck board. It looks like that's the one you reconnected. Not sure why you cut that wire as it's usually using a connector on the neck board side.

You might also have an additional ground wire that connects the pcb chassis metal parts to the tube chassis metal. It would make sense that you disconnected such to remove the pcb from the chassis. This last however is just speculation. Maybe someone with the exact same chassis can shine a light.

[Alaska]

The polarity of the degaussing coil is not important. So, it doesn't matter how you insert that plug.
The video signal connector should be mounted in correctly. You usually have RGB GND and sync.
If you put it in incorrect, you will short one of the color outputs of your game pcb to gnd.
Sometimes, the letters RGB are marked on the pcb, and the wires going to the connector have red, green and blue isolation.
Another thing you can do is find the ground pin with an ohm meter. That one should correspond with the ground of the connector.
The ground pin should measure approx 0 ohm in reference to the chassis which is also ground.

Normally, you have a ground wire going from the wire that runs across the picture tube to the neck board. It looks like that's the one you reconnected. Not sure why you cut that wire as it's usually using a connector on the neck board side.

You might also have an additional ground wire that connects the pcb chassis metal parts to the tube chassis metal. It would make sense that you disconnected such to remove the pcb from the chassis. This last however is just speculation. Maybe someone with the exact same chassis can shine a light.

That is a lot of help!  Thank you. I'll use my multimeter to check for ground.

The reason I had to cut the high voltage ground is WG and Zenith, for whatever reason, soldered the ground directly to the board for this model and opted not to use a pin connector.

[Alaska]

I downloaded a copy of the manual for the k7000 and was able to locate the proper orientation of of the Red, Blue, Yellow, Green harness. Strangely enough the wires coming off my monitor are Red, Blue, Brown and Yellow. Regardless of the conflicting colors (Yellow, Green on diagram and Brown, Yellow on my harness) I am confident that the wires are now connected properly to the chassis.

I took a look on the neck board for a grounding wire port missing a wire. The neck board is a P448 (85X0217B W.G.E.C 1986). The only potential spot would be above the C204 port, between C204 and the main high voltage ground. There is a solder point at this position that reads 8K on the board, no wire is connected though, just a solder point. Unfortunately it is not shown on the P448 schematic. Anyone worked on or own a WG/Zenith 25" k7000(a) that might know if this is the correct spot for this wire?

What a hasselhoff  !

[DudeRegular]

This is a shot From my k7000a
See that wire at the top middle of the neck board. Check against yours.

[obcd]

Are you sure that wire is a ground wire?
On most monitor chassis I have seen, you have 2 wires running from the LOPT to the neck board.
One wire is the focus voltage (which is the red one on your picture) and the other is the screen voltage.
As the wire seems to have a rather thick insulation, it could be the screen voltage wire.

Also confusing is the fact that on previous picture you have reconnected a black wire that seems to be connected to the wire running
across the picture tube. On the neckboard, the ground wire looks to be a gray one.
That white thing it's connected 2 looks like a one pin connector, but you said that the wire was soldered to the neck board.

So, where is that gray wire connected 2? (Just to be sure you won't mess things up)

[Kevin Mullins]

BOTH black wires go to the neckboard, they are BOTH grounds, one to the aquadag on the tube, the other to the heatsink near the flyback. They are soldered in the same location DudeRegular pointed out. Note that there are TWO holes right in that area next to eachother, I'm sure one of them will have a bit of broken piece of wire sticking out of it now.

[obcd]

Makes sense on that last picture.

In that case, the gray wire going to the connector will be the screen voltage coming from the LOPT.