My monitor has stopped working; care to help me fix it?

aclbandit

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The other night, I switched from my newly-crafted Dreamcast-to-JAMMA box back to a standard CPS2 board in my "Big Blue" cab. When I turned it back on, there was an odd buzzing sound, a popping noise, and then the monitor didn't power on ever again.

It does NOT make any noise when powered on, so I don't think it's the flyback; if that's bad, I think it's supposed to buzz or something, right?

It's also not the fuse: although the monitor fuse that was in it had odd clouding on the inside of the window, I replaced it with the same thing and it still doesn't work.

I saw XianXi's thread about monitors and grabbed the (exceptionally informative) flowchart, but it's a little over my head -- I've never done anything more complex than a cap kit replacement before.

I do not own a multimeter, though I really need to make that investment soon, so I'd like to start with suggestions of things I can do without one and try those first, if available.

Worst case, I hear that ChannelManiac is THE guy for PCB repair, but I'm worried (based on my lack of knowledge) that something besides the main chassis could be the problem.

The monitor chassis is a Wells-Gardner 25K7193, and the tube is a Phillips MO8X.

All useful information is appreciated. Do keep in mind that, although I've learned a lot since getting into the arcade scene, I'm still very much a noob when it comes to electronics repair.
 

Dion

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First of all you MUST have a multimeter if you own arcade games. Go buy a cheap one at least. Second, always test your fuses with a meter. The eye test doesn't always work because the fuse can fail but still look good. If your fuse did blow (clouding certainly makes it sound as such) then there is usually a reason. Simply replacing a fuse will usually result in a second blown fuse.

Check your fuses in you power block usually located in the bottom of the cab. One of those could be blown. If you had a meter you could check if you have ac coming into the monitor.
 

aclbandit

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First of all you MUST have a multimeter if you own arcade games. Go buy a cheap one at least. Second, always test your fuses with a meter. The eye test doesn't always work because the fuse can fail but still look good. If your fuse did blow (clouding certainly makes it sound as such) then there is usually a reason. Simply replacing a fuse will usually result in a second blown fuse.

Check your fuses in you power block usually located in the bottom of the cab. One of those could be blown. If you had a meter you could check if you have ac coming into the monitor.

Okay, I'll pick up a multimeter when I get paid monday.

Dunno if I mentioned this, but I know that at least something is working as far as power goes, since everything else (marquee light, sound, the game itself (even though you can't see it)) works fine.

I just can't figure out what could have happened; it's not like I changed anything?

Once I get a multimeter, where do I start?

EDIT: You said "fuses" in the power block, as in plural. I'll take a look; the thing needs a new power supply anyway, this one has always looked like a fire hazard.
 

Dion

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take several pics of the inside of the cab. We'll try to locate the other fuses. Usually there are fuses on the ac coming into the cab and some in line with the isolation transformer (which this monitor requires). Usually when AC comes into a cab it is split. AC powers the monitor and marquee lights usually. It is also fed to the power supply which then converts it to DC at various voltages which the pcb uses.
 

Arcademan

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When the game is turned on and you can still hear the sounds from the game and not see the picture, in almost every case it's a monitor related issue so you can rule the game board out.
 

Grinwing

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I have that same monitor. I just picked up the game last night and the monitor had no glow in the neck. Tested to make sure power was getting to the monitor with the meter, check. Pulled monitor and pulled the board. checked the diodes at the end of the power section and they were all good, but the ceramic tower piece had one of the legs burnt and no longer making contact. We desoldered it, cleaned all the burnt stuff off and resolded it. Also found a couple of other spots where the solder had cracked and was going to fail if not already. Put it all back together and it works like a champ.

The components we checked are on the tube side of the board (in the corner) opposite of where the power cord and flyback are. The power comes in on the other side and runs across the board. You can easily follow the traces from the power wires, through the fuse, and into the diodes and the ceramic tower in the corner (forget the name of the component.)

When you pull the board out of the chassis, do a visual inspection of the flyback to see if there are any burnt spots on it.
 

shess

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That flowchart was specific to the Hantarex Polo. Here's the one you need for the WG K7000: http://dosmame.mameworld.info/images/other/wg-k7000-flo.jpg

You should be able to get a pretty low end multimeter from Sears or Radioshack. Just as long as it's digital and has the continuity check. Like Grinwing said, you probably burned something since it was all of a sudden and you heard a pop. Look for burned components, especially near the flyback.

The good news is that the WG monitors are extremely common so troubleshooting advice and parts should be easy to come by.

Scott
 

aclbandit

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take several pics of the inside of the cab. We'll try to locate the other fuses. Usually there are fuses on the ac coming into the cab and some in line with the isolation transformer (which this monitor requires). Usually when AC comes into a cab it is split. AC powers the monitor and marquee lights usually. It is also fed to the power supply which then converts it to DC at various voltages which the pcb uses.

I'll try to get some pics today; thanks for helping so far.

When the game is turned on and you can still hear the sounds from the game and not see the picture, in almost every case it's a monitor related issue so you can rule the game board out.

I figured as much, since literally every other part of the machine seems to be working except the monitor.

That flowchart was specific to the Hantarex Polo. Here's the one you need for the WG K7000: http://dosmame.mameworld.info/images/other/wg-k7000-flo.jpg

You should be able to get a pretty low end multimeter from Sears or Radioshack. Just as long as it's digital and has the continuity check. Like Grinwing said, you probably burned something since it was all of a sudden and you heard a pop. Look for burned components, especially near the flyback.

The good news is that the WG monitors are extremely common so troubleshooting advice and parts should be easy to come by.

Scott

The flow chart is still a little over my head, but I'm glad to have it. And yes, I'm quite glad it was the CPS2 monitor that blew and not the Neo. My Neo is some off-brand, whereas the Big Blue is a W-G.

EDIT: And, just to be clear, "over my head" does NOT mean "OMG I can't do it," but rather it means I'll have to learn how to do it once I get the multimeter.
 
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aclbandit

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Pictures, as promised! All can be clicked for higher resolution, but be aware that my phone camera is balls.

Back of the monitor, everything still plugged in:


Chassis:


Power Supply:


JAMMA harness and kick harness:


Close-up shot of one part of the chassis (took this one because I thought I had to unplug all those little wires, so I wanted to know where they went. I didn't have to unplug them... and I don't think they come unplugged anyway):


Back of one side of the PCB on the monitor "neck" (I think that's what it's called?):


The other side of the neck PCB:


The inside of the power supply (the fuse, when I dusted it off, looks fine; I only found one fuse so far):


Also, I can't quite get the chassis PCB out -- there are these two wires that go up to the PCB on the back of the monitor neck. I won't lie, when I ran into these two on the Neo to do the cap kit, and I just cut them and then re-soldered 'em back together later; I'd like to NOT have to do that this time, if there's a correct way to remove them:


Unrelated (at least directly) to functionality: this thing is NASTY on the inside. Grime like you wouldn't believe. Ewwwwww.

If any further pictures are necessary, just let me know and I'll take care of it.
 

Dion

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As soon as you get your meter we can do some tests. BTW. When you remove the chassis you need to remove the neckboard from the tube. You'll do a cap kit while the neckboard is still attached to the chassis.

To remove the neckboard grab it from both sides and genty wiggle it back and forth until it comes off. Its simple.
 

aclbandit

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As soon as you get your meter we can do some tests. BTW. When you remove the chassis you need to remove the neckboard from the tube. You'll do a cap kit while the neckboard is still attached to the chassis.

To remove the neckboard grab it from both sides and genty wiggle it back and forth until it comes off. Its simple.

Thanks! Came right off!

Only trouble is now there's a grey wire that goes from the neckboard up to the... um... white rope/twine thing around the tube. I can't figure out how to get the grey wire off.

Halp?
 

Dion

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Plugs onto the neckboard. Should come off when pulled.
 

aclbandit

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Plugs onto the neckboard. Should come off when pulled.

Well... it was soldered on. Dunno if it's supposed to be firmly attached at both ends, but it's a wire with metal on the inside, so it'll always go back together. I snipped it; I'll re-solder it and properly cover it when I have to put stuff back together. Sucks, but it seemed the safest option.

Here's a better picture of the chassis and neckboard, respectively:


 

aclbandit

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I now own a multimeter, and I started following the flowchart. Did a continuity test on the new fuse (it's blown too -- apparently it was not just a fuse problem), so I moved on to testing transistor Q11. I haven't actually been able to FIND that transistor, so we'll see what I can do when I find it.

Any tips/help?

EDIT: Checked it once i found it -- it's a much larger transistor than those I've seen before with the D-shaped tops.

I think it's good, since its resistance is 183.5Ohms (units may be incorrect -- I didn't notice this thing has automatic range, so this could be kOhm)

Diodes 19-22 check out: a bit over 200Ohms each (same as above regarding range)

I had already tried operating without degaussing coil to no avail, but perhaps not with a good fuse. I'll check that if nothing else works.

C36 and C38 are both something like 180kOhm, so I think they're good -- "open" means "really, really huge resistance," right?

Diode 18 is .828MOhm. I don't know what that means...?
 
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aclbandit

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I also believe I should mention that some of the capacitors have white stuff around them; I'm pretty sure that means they're leaky, but the ones mentioned in the flow chart are not any of the leaky ones.
 

Dion

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The white stuff is just silicone. Its there so that the caps don't move around. Also to make doing a cap kit a bit more difficult. Just a bit inconvenient. You won't normally be able to see a cap leaking. You'll see the results of the corrosion from the electrolyte.

When testing diodes remember that the current can only travel one way. If you are getting the same reading both ways it is open. Also, remember when you test diodes and resistors that you need to desolder one lead and pull it out of circuit.

If you are blowing fuses I would test the HOT and do a visual inspection of the flyback looking for burns and cracks.
 

aclbandit

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The white stuff is just silicone. Its there so that the caps don't move around. Also to make doing a cap kit a bit more difficult. Just a bit inconvenient. You won't normally be able to see a cap leaking. You'll see the results of the corrosion from the electrolyte.

When testing diodes remember that the current can only travel one way. If you are getting the same reading both ways it is open. Also, remember when you test diodes and resistors that you need to desolder one lead and pull it out of circuit.

If you are blowing fuses I would test the HOT and do a visual inspection of the flyback looking for burns and cracks.

Okay. Can you give me some more details? This is the first time I've ever had to repair monitor innards, so I don't know much about what that means.
 

aclbandit

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Also, will any K7000 series chassis work with this neck/tube, or not? If so, I might consider buying a replacement while I work on this one.

I'm having a get-together soonish, and I really need this working by then.
 

aclbandit

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Also, will any K7000 series chassis work with this neck/tube, or not? If so, I might consider buying a replacement while I work on this one.

I'm having a get-together soonish, and I really need this working by then.

*bump*

Still unsure if I could pick up a replacement while I try to fix this one. Any help, either with buying a spare and/or details on HOT/Flyback checks?
 

Dion

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Yeah you can buy another K7000 chassis as long as its for a 25" monitor.

Bob Roberts has all the parts you need also.
 
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aclbandit

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Yeah you can buy another K7000 chassis as long as its for a 25" monitor.

Bob Roberts has all the parts you need also.

Great. I've ordered one that's supposed to be functional.

Now there's less pressure to fix this one immediately. *phew*

Is there a good way to tell if the HOT and/or Flyback is dead? I don't see anything wrong with either as far as I can tell, but I don't really have much for comparison.
 

aclbandit

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Got my "new" chassis in the mail (new to me), and plugged it all up. It's a K7000 series, supposedly from a 25".

Something's wrong, though I don't know what. Hopefully it's just something I forgot or something that needs adjusted.

The screen looks like this:


That's supposed to be Chun Li on the SSF2X intro. But it's in a sorta smallish box in the middle of the screen, and it's all crazy-lookin'.

What's next?
 

Dion

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Adjust your v-hold and h-hold pots first to stabilize the picture. If your v-size pot doesn't fill out the screen then its possible that its a 19" chassis. Can you take a pic of the entire monitor so I can see the game image better?
 

aclbandit

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Adjust your v-hold and h-hold pots first to stabilize the picture. If your v-size pot doesn't fill out the screen then its possible that its a 19" chassis. Can you take a pic of the entire monitor so I can see the game image better?

Actually, I fucked around with all the pots a little bit, and I did manage to get a clear picture. I turned the V-POS all the way up, and it *almost* fills up the screen vertically, but not quite. Horizontally it's still tiny.



Thanks for being so helpful so far.

EDIT: Never thought that it might be relevant, but the main chassis board says P447. Based on a Google search, a 19" tube is mentioned, but so also is the 25" -- this page says P447s come in both sizes. I really hope it's not a 19". It was advertised as a 25" chassis.
 
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channelmaniac

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Ping Chad over at Arcadecup.com and ask him the differences between the 2 chassis. Maybe you can swap a few simple components.
 
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