Monitor help needed, probably newbie-ish

da66en

New member

Donor 2011
Joined
Aug 29, 2011
Messages
241
Reaction score
3
Location
Waukesha, Wisconsin
First, discharging a monitor. Instead of factoring a lamp cable with alligator clips on the end, can I just use jumper cables for a car? Seems like it would be fine to do so, but no one has recommended it yet.

Second, my monitor has problems. I am going to cap kit and replace the flyback, but am I wasting my time? Here's the run down:
Neo Geo 4slot, 25". NOT a WGK7000, but some kind of Kortek/A-One. Prevailing thought is that it's a K7000 knock-off.
Brightness and focus is mostly OK, but more blurry than I'd like. If I increase brightness on flyback, brightness is increased but becomes more out of focus.
Focus adjustment on flyback works, but I have it cranked all the way and still out of focus.
The horizontal adjustment knobs work, but regardless of adjustment it is still creating a picture that is a little too big for the monitor.
Vertical adjustment knobs work, but doesn't use 100% of the monitor.
Sometimes portions of the screen get shakey/wavey (common symptom for needing a cap kit).
Haven't tried the adjustments on the neckboard yet.

Thanks for your help.

Edit: Pix added on post #8
Edit: PCB markings added on post #14
Edit: Fix description (blue tint is expected on Neo Geo crosshatch, now getting wavy/shaking)
 
Last edited:
First, discharging a monitor. Instead of factoring a lamp cable with alligator clips on the end, can I just use jumper cables for a car? Seems like it would be fine to do so, but no one has recommended it yet.

Second, my monitor has problems. I am going to cap kit and replace the flyback, but am I wasting my time? Here's the run down:
Neo Geo 4slot. I believe it's the original monitor and chassis (can't find identifier and doesn't match any pics I've seen on the web. Haven't taken chassis out yet for ID).
It is a little dim and out of focus. If I increase brightness on flyback, brightness is increased but becomes more out of focus.
Focus adjustment on flyback works, but I have it cranked all the way and still dim.
If I am in cross hatch mode, the outer rim is blue tinted.
The horizontal adjustment knob works, but regardless of adjustment it is still creating a picture that is a little too big for the monitor.
Haven't tried the adjustments on the neckboard yet.

Thanks for your help.

For a typical raster monitor, Jumper cables are fine. Clip one end of a lead to monitor frame, the other same color lead to the (conductive) part of a long screwdriver shaft. Place left hand in pocket, and slip the screwdriver blade under anode cap, making contact with anode clips. If you hear a snap, wait 30 seconds and do it again. You should hear either no snap or a slight tick. Repeat until you hear nothing. If the monitor's been off for any lengh of time (hours or days) you will likely not hear anything.

Make sure your screwdriver shaft is conductive (NON CHROME COATED) and your handle is NOT conductive.

As to answering the rest of your questions on the monitor chassis, please supply us with some ID numbers or better yet, PICS.

There are chassis out there that are not worth repairing, because parts are not available. Pics will help us determine whether or not you have one that can be repaired.
 
Most monitors are worth fixing. There are a couple out there that aren't, due to parts unavailability or overall crappyness, but caps are cheap and easy to install - if the monitor is generally working, go ahead and cap it, it's usually an improvement.

When you pull the chassis, look carefully at the flyback, and inspect around the focus assembly for cracks or burns. Also, if it's a WG7000 and the flyback has white knobs, you should replace it regardless.

Car jumper cables are WAY overkill. They'll work, much the same way that it's possible to kill a fly with a sledgehammer, but your normal "cliplead" is much better suited to the task. It might be hard to get the huge clip on a jumper cable to stay attached to a screwdriver. Just get some of those small alligator clip leads from Radio Shack. They're handy for a thousand things, not just discharging monitors.

-Ian
 
If you are really paranoid..then get yourself a pair of rubber gloves. The first time it pops to discharge you will jump. lol
 
Make sure your screwdriver shaft is conductive (NON CHROME COATED) and your handle is NOT conductive.

Ah good point, I haven't thought of that.

smalltownguy2 said:
As to answering the rest of your questions on the monitor chassis, please supply us with some ID numbers or better yet, PICS.

There are chassis out there that are not worth repairing, because parts are not available. Pics will help us determine whether or not you have one that can be repaired.

I will try to get some pics up in the next few days, wasn't planning on taking the chassis out just yet.

That80sGuy said:
If you are really paranoid..then get yourself a pair of rubber gloves. The first time it pops to discharge you will jump. lol

I've done some consulting work with a company that makes 500KV transformers. I also worked on one of their products that generated 30KV - I used some heavy duty gloves and hope to get my hands on a pair. I would consider myself having a reasonable amount of paranoia.
 
I've done some consulting work with a company that makes 500KV transformers. I also worked on one of their products that generated 30KV - I used some heavy duty gloves and hope to get my hands on a pair. I would consider myself having a reasonable amount of paranoia.

Some other monitor gurus can back me up on this, but gloves won't help. 30KV finds a way. Better to make sure you've used a proper discharge tool.

Really you should be using a high voltage probe to discharge the monitor. They can be had cheap and are worth the investment. Ask someone who's been bit by a monitor if they think $20 is money well spent.

As to removing the chassis, you're going to have to take it out to work on it, so as soon as its discharged, remove it. But you still can take pictures of it while mounted. Most of us here will be able to ID it even from a crappy cell phone pic.
 
Some other monitor gurus can back me up on this, but gloves won't help. 30KV finds a way. Better to make sure you've used a proper discharge tool.
No need for gloves. The voltage is high, but the current is incredibly low. The amount stored in the tube WILL NOT kill you. Always discharge, because if you don't, it'll hurt like hell.

Honestly, I have no idea why so many people are so deathly afraid of monitors. The precautions are there because yes, they are dangerous. So is a BB gun. But neither of them are going to end your life. If you stop and think about what you are doing, and follow instructions, you won't be hurt.

Really you should be using a high voltage probe to discharge the monitor. They can be had cheap and are worth the investment. Ask someone who's been bit by a monitor if they think $20 is money well spent.
Waste of money if you're just using it to discharge. It's a handy tool for working on color vector monitors where you have to set the HV manually, but if you're doing raster monitors, for the most part, you'll never ever need it.

Take a normal flat head screwdriver. Clip one end of a cliplead onto the shaft, the other end to the monitor's frame. Slide the screwdriver under the suction cup until you hear the little pop, or feel it touch the metal tab in there. Do it again, just to be safe, and pop the suction cup off the tube - use the screwdriver to help you unclip the metal tabs from inside the anode hole.

The tube will occasionally tend to "recharge" a bit. It'll get enough of a charge to scare you - about like shuffling your feet on carpet and touching a doorknob. So, if you don't want to be surprised, discharge the now disconnected tube again before reconnecting the chassis.

The only special tool you need when working on monitors is common sense.

-Ian
 
Some other monitor gurus can back me up on this, but gloves won't help. 30KV finds a way. Better to make sure you've used a proper discharge tool.

Really you should be using a high voltage probe to discharge the monitor. They can be had cheap and are worth the investment. Ask someone who's been bit by a monitor if they think $20 is money well spent.

I'll be careful. :)

smalltownguy2 said:
As to removing the chassis, you're going to have to take it out to work on it, so as soon as its discharged, remove it. But you still can take pictures of it while mounted. Most of us here will be able to ID it even from a crappy cell phone pic.

Ok, consider yourself challenged. Pics are attached.

RetroHacker said:
No need for gloves. The voltage is high, but the current is incredibly low. The amount stored in the tube WILL NOT kill you. Always discharge, because if you don't, it'll hurt like hell.

Honestly, I have no idea why so many people are so deathly afraid of monitors. The precautions are there because yes, they are dangerous. So is a BB gun. But neither of them are going to end your life. If you stop and think about what you are doing, and follow instructions, you won't be hurt.

There are 5 adjustment knobs on the neck board. So, I shouldn't be deathly afraid to adjust these while the monitor is on?

Hopefully one of them is contrast? There is no contrast knob on my monitor.

PS pics don't show it but I have black flyback.
 

Attachments

  • main.jpg
    main.jpg
    100.5 KB · Views: 52
  • subpcb.jpg
    subpcb.jpg
    99.3 KB · Views: 47
Some other monitor gurus can back me up on this, but gloves won't help. 30KV finds a way.

True. Here's a video of power linemen's gloves vs 7.2KV
http://www.youtube.com/watch?v=2_4gsPe7BuM&feature=player_detailpage#t=152s

And for the other poster seeking to buy linemen's gloves, keep in mind that even at 7.2KV they have to be tested *daily* for flaws to retain their integrity. Otherwise they are no better than that rubber that rode around in your wallet for years when you were a teenager...

The only special tool you need when working on monitors is common sense.

And a plastic allen wrench :)


There are 5 adjustment knobs on the neck board. So, I shouldn't be deathly afraid to adjust these while the monitor is on?

No, but don't touch the exposed contacts on the neckboard.

pics don't show it but I have black flyback.

Not the flyback color (most are black), but the knobs on the flyback.
 
Last edited:
Hmm. Can't say I recognize that exact chassis off the top of my head, but it looks like a Sharp Image.

The knobs on the neckboard control the individual guns. I wouldn't adjust them unless you need to, it's easy to get an image that looks really crummy by overdriving one color more than the others.

There is no "contrast" knob, but you can adjust those video level controls (by the video input header) to see if you can brighten up the individual color signals. The SCREEN and FOCUS controls on the flyback should allow you to brighten up and focus the image.

Any of the controls with plastic knobs are safe to adjust with your fingers while the monitor is on. Only thing you have to watch out for are K7000's with cracked flybacks/white knobs. Sometimes they bite when you try to adjust the knobs...

-Ian
 
Not the flyback color (most are black), but the knobs on the flyback.

Ah. My flyback knobs are black.

RetroHacker said:
There is no "contrast" knob, but you can adjust those video level controls (by the video input header) to see if you can brighten up the individual color signals. The SCREEN and FOCUS controls on the flyback should allow you to brighten up and focus the image.

I haven't played with those knobs yet (they seem like a scary reach, to me) - but my problem thus far has been that increasing the brightness has killed my focus. Will adjusting the RGB knobs have a better effect than the brightness on the flyback or the brightness on the sub-pcb?

I also discovered something else - the monitor/chassis is powered by isolated AC, but the chassis (the metal holding the monitor and PCB together) is wired to ground from the AC (not line or neutral). Is that correct?
 
I haven't played with those knobs yet (they seem like a scary reach, to me) - but my problem thus far has been that increasing the brightness has killed my focus. Will adjusting the RGB knobs have a better effect than the brightness on the flyback or the brightness on the sub-pcb?

The sweet spot for your focus knob is usually somewhere in the middle. Use a mirror or a partner and try backing your focus off a bit.


I also discovered something else - the monitor/chassis is powered by isolated AC, but the chassis (the metal holding the monitor and PCB together) is wired to ground from the AC (not line or neutral). Is that correct?

That is the frame of the chassis. It should be grounded.
 
That chassis looks like it might be a Kortek variant..... check on the side of the large heatsink around the flyback for labels of any kind.
 
The sweet spot for your focus knob is usually somewhere in the middle. Use a mirror or a partner and try backing your focus off a bit.

I will try the flyback again, but I didn't have luck on my first try for getting a good focus. It also doesn't solve the problem with the horizontal being a little bit too big and the blue tint around the whole screen.

I think I almost found the chassis. It looks very much like the A-One 20" on this site:
http://www.zax.com.au/spare_parts/monitor-chassis.html

Some things to note:
It is attached to a 25" monitor.
My chassis has a sub PCB near the coin slot, that A-One has it attached to chassis PCB.
Marking on the top of my PCB is AM-0227, and the marking on the bottom of the PCB is A-ONE N25M
 
Any thoughts? My last bump before I try e-mailing ArcadeCup or other repairmen for help identifying chassis and opinion of monitor.
Pictures on post #8, PCB markings on post #14
 
Get that one-off piece o crap out of there and install something well known.

You'll pay less for a replacement chassis then you will to fix this one.
 
Get that one-off piece o crap out of there and install something well known.

You'll pay less for a replacement chassis then you will to fix this one.

Ok, I will look to get rid of this 'piece o crap'. Recommend any dealers?

The blue tint around the edges in my original description wasn't a problem, it was supposed to happen on a Neo Geo crosshatch.

Yesterday the screen got wavy/shakey sometimes in some areas, a common problem fixed by cap kit?

Will running the monitor with a faulty chassis damage the monitor?
 
So I took out the glass in front of the monitor and notice a pretty thick film of black soot (cigarette smoke?) on the inside of the glass and on the monitor itself. Cleaned it and got a huge improvement in brightness and focus.

Still more blurry than I'd like.

No luck ID'ing the chassis. I did find one discussion thread on neo-geo.com who had the same chassis that I had, but that's it:
http://www.neo-geo.com/forums/showthread.php?220747-arcade-monitor

neo-geo.com forum discussion and some e-mails with monitor repairmen, and the prevailing thought that this is a WGK7000 knock off. Going to try a WGK7000 cap kit and Digikey/Mouser any caps that I am missing in the kit.

If horizontal doesn't get fixed by the cap kit (chassis is putting out image too wide for monitor), should just be an easy adjustment of the horizontal coil?

If vertical doesn't get fixed by the cap kit (chassis is putting out an image too short), what is in the process of fixing that?

Any recommendations for picking up a new chassis?
 
Back
Top Bottom