Centipede monitor blackout

super56k

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So my UR Centipede has this issue with it's monitor where when you turn the game on, it's crisp and clear and the game is wonderful to play then after about 5mins, it goes black possibly even off. If I turn the game off and let it sit, then back on, sometimes it comes back for another 5 mins. Every once in a while it will come on and last a whole night but that is becoming rarer and rarer. When the screen is black, the game plays blind so I don't think it's a board issue. It had this problem before and I had a TV shop repair it. I do alot of repairs myself with boards and components but when it comes to monitors, I am a noob / afraid of dieing. I believe the monitor is a Wells Gardner K7000. Any ideas?
 
post some pics of the chassis so we know what you have.

if it is a K7000 then it needs a cap kit, new fly, and a re-flow at the very least.

Peace
Buffett
 
Yeah, I'm with buffett on this one - cold solder joint somewhere on the HV rail for the monitor. Time to get someone to take a peek at your monitor chassis.
 
Yeah, I'm with buffett on this one - cold solder joint somewhere on the HV rail for the monitor. Time to get someone to take a peek at your monitor chassis.

HV rail? High Voltage rail correct? Would that be the underside of PCB where the flyback solders to the board? I have no problem with re-flowing solder and replacing caps is pretty easy but I'v never repaired a monitor because they hold high voltages. I can probably get a picture tonight.
 
that is correct.

but before we get into it to much the pics will help us give better idea of where to start the repair progress.

Peace
Buffett
 
So ...when it comes to monitors, I am .. afraid of dieing

There's the problem- fear.

Let go.

Reach in there while your monitor is powered up, and touch the case of your Horizontal Output Transistor. You'll get a hell of a shock, but you will learn that it won't kill you.

Then you can do ANYTHING!

Kerry
 
There's the problem- fear.

Let go.

Reach in there while your monitor is powered up, and touch the case of your Horizontal Output Transistor. You'll get a hell of a shock, but you will learn that it won't kill you.

Then you can do ANYTHING!

Kerry

It must be Friday.
 
Pictures

Sorry for all the delay, I've been busy. Here are some pictures of the monitor in question:

2012-08-19_12-42-50_758.jpg


2012-08-19_12-44-27_922.jpg


2012-08-19_12-43-56_687.jpg


2012-08-19_12-44-05_846.jpg


2012-08-19_12-44-13_570.jpg


2012-08-19_12-43-04_256.jpg


2012-08-19_12-43-14_408.jpg


Also, before I took it out, I did a closer inspection. When I turn the game on, the picture comes up crisp, clean, and stable. It looks beautiful. Then after about two minuets, the picture disappears. When this happens, the marquee restarts like it's had power cut to it but I had a game going and the sound FX where not interrupted in that current game. There was no neck glow on the monitor after this and you could hear the static fizzle like you normally here when a CRT is turned off. What do you guys think now? Thank you very much for the help so far. Without KLOV, I'd be lost.
 
You've got yourself a K7000 with what looks to be factory caps on the board. The shut down is either cold solder or bad caps or both (I'm guessing both). The Flybacks and part of the B+ rail are notorious for having cold solder on those things.

While monitors can shock the s*** outa you they wont kill you unless you try to make it kill you. ie, drop the monitor on your head from 30 feet or something stupid like that. Many of us here have been shocked by a monitor and live to tell about it.
 
You've got yourself a K7000 with what looks to be factory caps on the board. The shut down is either cold solder or bad caps or both (I'm guessing both). The Flybacks and part of the B+ rail are notorious for having cold solder on those things.

While monitors can shock the s*** outa you they wont kill you unless you try to make it kill you. ie, drop the monitor on your head from 30 feet or something stupid like that. Many of us here have been shocked by a monitor and live to tell about it.

Thanks for the reply. So what is the B+ rail? Would that be a trace on the underside of the PCB where the flyback is attached? Could caps cause the whole thing to shut completely off? I could always reflow the solder and go from there if I can figure out which part needs reflowed.

When I took this to the TV shop guy to get it fixed the first go round, he just grabbed the anode clip and yanked it right off. I told him I had not discharged it and he said he never messes with that and they all discharge themselves. I guess if I ground the anode to the chassis before I disconnect it or touch anything, I should be safe right?

EDIT: It turns out I have another monitor EXACTLY like this one in storage but it does nothing when powered up so I never messed with it.
 
The TV guy is right in that most newer TV's will discharge themselves but not all. If he did that with a GO7, K4900 or a older Nanao (sp?) he would have gotten nailed. Probably wouldn't bother him too much though, you do get used to it.

The B+ rail is just the name for the trace that supplies the primary operational voltage/current across the board. You may also hear "ground rail" referring to the grounded traces on the board. If you look at the schematic or cross reference the voltage regulator (the black thing mounted to the long side of the frame) you will see which pin is the output from the regulator. Thats the "B+" rail. Follow it around and I bet you'll find some bad solder joints.

Based on what your saying that the monitor is doing its going to at least need to have its caps replaced.
 
The TV guy is right in that most newer TV's will discharge themselves but not all. If he did that with a GO7, K4900 or a older Nanao (sp?) he would have gotten nailed. Probably wouldn't bother him too much though, you do get used to it.

The B+ rail is just the name for the trace that supplies the primary operational voltage/current across the board. You may also hear "ground rail" referring to the grounded traces on the board. If you look at the schematic or cross reference the voltage regulator (the black thing mounted to the long side of the frame) you will see which pin is the output from the regulator. Thats the "B+" rail. Follow it around and I bet you'll find some bad solder joints.

Based on what your saying that the monitor is doing its going to at least need to have its caps replaced.

I've replaced caps on other electronics before so that's not too hard. I did a complete cap kit on my NeoGeo MVS-4-25 to get it back up and running properly. So it sounds like the best thing for me to do now is...

1. discharge the tube
2. reflow any cold solder joints I see
3. install a cap kit

If so, will a cap kit for a "k7000" work on all monitors in the series? I.E. this k7901? Looks like Bob Roberts and Arcade Shop Amusements carry them... Anywhere better to get them?
 
Yeah, a run of the mill k7000 cap kit will do the job.

Great. Since I will be doing a monitor repair for the first time, I decided to go ahead and order kits for two other monitors that have minor problems. My NeoGeo's monitor has faint jail bars and shakes from when things flash on the screen and my Donkey Kong Jr. shakes a bit off and on. I got the model numbers off those two monitors but I can't seem to find kits for them.

Donkey Kong has a "18-Z2AB" and I can only find kits for a "Z2AW"

NeoGeo has a WG "25k791" Isn't that number too short? Is there a K700 series?
 
Unless some one has changed the monitor in your DKJr its a 20EZ (or is that EZ20?). Either way its a Sanyo monitor and its not a fun one to be initiated in the world of monitor repair on. Its a good one to try if you want to see how easy the others are though!

EDIT: This is of course assuming that you have an upright factory DKJr.
 
Unless some one has changed the monitor in your DKJr its a 20EZ (or is that EZ20?). Either way its a Sanyo monitor and its not a fun one to be initiated in the world of monitor repair on. Its a good one to try if you want to see how easy the others are though!

EDIT: This is of course assuming that you have an upright factory DKJr.

Cocktail and it's marked with the same date as the board. 1982.
 
Centipede / WG K7901

Ok so I caped the K7901 in my Centipede and checked for cold solder joints but the issue persists:

I started the game up and after about 3mins the screen went blank but the game still plays blind. I turned it off and then on again and the screen stayed up for the rest of the night until I turned the game off (about 2 hours). I turn it on this morning and it goes off after 2mins. When the screen is blank, there is no neck glow. When the screen is on the picture is PERFECT.

Could this be an issue with the "BIG BLUE"? It looks super old and dusty.

EDIT: Could this be a tube issue? I have a spare monitor EXACTLY like this one but it does nothing when powered on. Could I just take the tube from it or would that be a waste of my time?
 
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