Help with Monitor Discoloration

[Peale]

Originally Posted by stonic

FYI he wasn't talking about moving the machine but rather putting a cap kit in.

And I was talking about discharge rules in general.

[Peale]

You do NOT need to discharge if you're only removing a monitor from a cabinet. Any work that involves removing the chassis from the tube then yes, you should discharge before andode removal, and after.

If you don't believe me, ask Ken Layton. If you don't already know who he is, he's a tech that's been in the industry for nearly 30 years. He's forgotten more about coin op then I'll ever know - and truth be told I don't think he's ever forgotten anything. He can give you exact model numbers for a ton of monitors, tell you quirks about each model, and then a part-by-part breakdown. He's mostly on BYOAC, KLOV and the Vendor Amusement message board.

[Peale]

Originally Posted by stonic

No, you don't *have* to if you're only removing it. Is it safer to do so? Hell yes, no matter what you or Ken say. Sometimes the *outside* of the tube has a charge on it - be it due to cheap construction, age, damage, etc. And with the whole monitor chassis being metal, anything is possible.

I gotta admit, I didn't think anyone could be so goddamn pissy over a safety precaution that takes a few seconds to do, and has nothing but a positive benefit for everyone involved. I was wrong.

Pissy? I have not sworn once, I'm not using objective language, precisely how have I been "pissy?"

And I'll take Ken's word over just about anyone's in regards to repair and safety in regards to arcade machines.

[SegaAges]

simmer down ladies, hehehe

i am going to solder the cold solder joint here tomorrow since i finally have a free day, and i will let you guys know how it goes. hell, i might even do it today.

if i still have fucked up color, we can go from there

[Peale]

Seriously, you now have to resort to namecalling? Then I'm glad you can't see me. And if that's all it takes to be added to your "list" your list must be pretty long.

I also never assumed anything...I only asked you a simple question. Nice deflection.

It's not about the length of time to do it - of course it only takes a few seconds. It's the fact that doing it UNNECESSARILY can also have it's consequences.

I don't care what you or Ken say, you never assume a monitor is discharged before doing anything with it.

One word: "duh". Neither of us stated that at all. We're both stating that you always discharge before doing any work. Ken doesn't use a screwdriver with a wire, he always uses a high voltage probe.

For anyone else that's reading: Ken is a service tech with over 30 years of experience in the coin op repair field. For anyone in the business, his word is The Gospel when it comes to service and repair.

Now, on to some actual content:

i am going to solder the cold solder joint here tomorrow since i finally have a free day, and i will let you guys know how it goes. hell, i might even do it today.

Excellent. This will probably sort you right out. This region is particularly noted for broken joints due to insertion and removal of the harness.

[SegaAges]

Ok, 2 things:

1.) can I request you guys take that argument somewhere else. I am getting assistance by both of you, which is appreciated, and I don't want this thread to get locked from 2 other people.

2.) I am going to start small tomorrow. I am going to resolder the solder joints just under where the harness plugs into the video board. hopefully that does the trick

[Peale]

Originally Posted by SegaAges

Ok, 2 things:

1.) can I request you guys take that argument somewhere else. I am getting assistance by both of you, which is appreciated, and I don't want this thread to get locked from 2 other people.

No worries mate; I think he's done.

Post back when you've touched up those joints and let us know how you did.

Have you soldered before? If not, you will want to practice on something you don't care about. Like tinning wires, or an old scrap circuit board.

[SegaAges]

Originally Posted by Peale

No worries mate; I think he's done.

Post back when you've touched up those joints and let us know how you did.

Have you soldered before? If not, you will want to practice on something you don't care about. Like tinning wires, or an old scrap circuit board.

Yeah, I am going to do some practice on an old scrapped motherboard

[Peale]

Good choice. Practice on the caps since they're thru-hole.

[SegaAges]

Yeah, I need more practice. I did nothing with my board today. I am going to continue to practice on that motherboard.

Ok, so I am not going to be messing with the soldering that deals with a small piece of the pin on the bottom?

Those are super hard for me to solder.

Some of the other ones, I thought I was doing good, and the solder point would look good, but the solder point next to it would turn a little brownish.

[Peale]

What kind of soldering iron do you have? Solder?

Remember to heat the part, not the solder.

[Ken Layton]

SegaAges:

You have a Wells-Gardner k7000 series monitor. Your exact model number is on that paper label next to the video/sync input connector. Your pictures were out of focus, but it looks like you have a 25k7191.

Some information on it is here:

http://jstookey.com/arcade/WG_25k7191/

The problem you are having is 99% causes by cold solder joints on that video input connector (male) header pins. The weight of the cable pulling on the wires causes the solder to go bad coupled with Wells-Gardner's poor soldering at the factory. The K7000 series is well-known for many cold (bad) solder joints all over the main board and optional remote adjustment board (if fitted).

If you are going to work on the monitor main board, you should discharge the monitor's high voltage. You should remove the boards from the monitor to work on them. Don't try the "balancing act" of trying to work on the boards while still in the monitor. Take the boards over to your work bench where you can work on them and see them under a good bright light. Examine the soldering closely. The most troublesome areas are at resistors R101 and R98. Use 60/40 rosin core "electronic" type solder. DO NOT USE THAT "LEAD-FREE" (all tin) crap solder or that acid core "plumber's solder".

Your pictures do show that your monitor has never had a capkit and it has it's original flyback transformer.

If you are removing a complete monitor from the cabinet there's no need to discharge it. However, you do need to disconnect the power cable, video/sync input cable, and frame ground wire from the monitor before lifting it out. Always have a helper handy to watch to be sure all cables are clear (not snagging on anything) and to help lift the monitor. Remember that 25" monitors are heavy (heavier than they look) and you don't want to drop it or break the neck of it. If you should decide to lay the monitor "face down", put a blanket or pillow down first. The tube will scratch itself under it's own weight and that is a permanent condition.

Some people remove the monitor to do cabinet work or to install a new or better monitor.

When I discharge a monitor I use a high voltage probe to do it. This is the best and safest way. You bleed the charge off quickly in about 15 seconds and with a proper load. You can see the voltage on the meter as it's discharging and without that dangerous SNAP of doing it with a screwdriver.

Sure you can discharge the tube with a screwdriver and a piece of wire. However, that can damage things. That sudden snap discharge can arc/burn the prong contacts inside the rubber suction cup thus making a poor connection later. Inside the flyback transformer is a high voltage diode that can be damaged by this sudden short circuit to ground.

I generally do not discharge a monitor just to move/remove it from a cabinet unless it's one of those oddball "two-piece" jobs where the tube is mounted to a piece of wood and the circuit boards are screwed to the side of the game cabinet.

I've been in this business since 1976 and have literally repaired over 1,000 monitors over the years.

[SegaAges]

Yeah, I need alot more practice soldering. I got a motherboard from an old pc I am practicing on, and everytime I try to heat the spot, I don't seem to heat it enough.

I will heat the spot by leaving it on the spot for about 3 seconds, and nothing will happen with the solder melting.

[SegaAges]

So I did it and was very careful with it, and now the monitor and marquee do not seem to be getting power. I am assuming it is power since the marquee itself is now not powering on

EDIT: I checked and the tube does not glow.

[Ken Layton]

Did you disconnect any connector that you may have forgotten to reconnect?

Are there any blown fuses?

All safety interlock switches in the correct position?

Power switch on?

[SegaAges]

Originally Posted by Ken Layton

Did you disconnect any connector that you may have forgotten to reconnect?

Are there any blown fuses?

All safety interlock switches in the correct position?

Power switch on?

I know that the power switch is on because the jamma board itself gets power.

As for fuses, I have no clue where they are located to check.
Also, for safety interlocks, I have no clue what those are.

The thing that is confusing me is the fact that the marquee gets no power. I should say the light fixture on top or whatever, but I did not think that had anything to do with the monitor. Could a safety interlock affect that? Or would a blown fuse affect that?

[SegaAges]

Where would the fuses be located for me to check?

I am sorry, I am new to this stuff, but want to learn.

Also, is there anything else that I can check since the marquee neon light and the monitor get no power, or does this sound like the culprit of a blown fuse?

EDIT: After some searching on the board, I found out that I have a
wells gardner 25k791

EDIT 2: sound also comes in.

[Ken Layton]

If that Sega STV is what you have, then it's in a Dynamo conversion cabinet. This could have several different internal wiring configurations depending on the cabinet model number (HS-x).

Here are pictures of two different power supplies that were used in these cabinets.

One is a Peter Chou 12 amp "screw terminal power supply. The other is a Peter Chou 200 watt "XT computer" style power supply.

If your cabinet has the XT computer style type of power supply then there should be a short (about 6" or so) dongle cable sticking out of the supply with a 3 pin flat white Molex connector. It will have black, white, and green wires. This connector is the 120 volt AC power output to the monittor's isolation transformer (and in some cabinets also to the light fixture). Is it possible you unplugged it and forgot to plug it back in? Maybe a pin scooted out of it's connector housing?

If your cabinet has the control panel AND the wood panel holding the gameboard and "screw terminal" type of power supply then there's a possibility that the slide out wood has snagged a wire or connector and pulled something loose/unplugged something.

In general, Dynamo cabinets do not use "safety interlock" switches. At least all the ones I've worked on over the years never had any.

[SegaAges]

Originally Posted by Ken Layton

If that Sega STV is what you have, then it's in a Dynamo conversion cabinet. This could have several different internal wiring configurations depending on the cabinet model number (HS-x).

Here are pictures of two different power supplies that were used in these cabinets.

One is a Peter Chou 12 amp "screw terminal power supply. The other is a Peter Chou 200 watt "XT computer" style power supply.

If your cabinet has the XT computer style type of power supply then there should be a short (about 6" or so) dongle cable sticking out of the supply with a 3 pin flat white Molex connector. It will have black, white, and green wires. This connector is the 120 volt AC power output to the monittor's isolation transformer (and in some cabinets also to the light fixture). Is it possible you unplugged it and forgot to plug it back in? Maybe a pin scooted out of it's connector housing?

If your cabinet has the control panel AND the wood panel holding the gameboard and "screw terminal" type of power supply then there's a possibility that the slide out wood has snagged a wire or connector and pulled something loose/unplugged something.

In general, Dynamo cabinets do not use "safety interlock" switches. At least all the ones I've worked on over the years never had any.

It actually used to be a Tekken 2 cabinet that I put a st-v board in.

This is what the cabinet looks like:

[SegaAges]

I will check all the pin connectors tomorrow and let you guys know what happens

[XYXZYZ]

That looks like a 3KOAM Z-Back.

[SegaAges]

Yeah, I got to put a hold on working on this for the weekend since I am in Kansas visiting a friend that got cancer

[SegaAges]

Here is an update. I not only checked the connections of the pins, but reseated them to ensure that they were secure.

I am still having the same symptoms of no marquee light and no power to the monitor. I am assuming that if the monitor got power even if something else was fucked up, I would still get the tube glowing.

What else can cause this to happen. The board obviously gets power because the sound comes on properly, which is telling me that the board gets power and is sending the signal to the speakers.

[Ken Layton]

Trace/follow the wires back from the monitor. There should be approx 120 volts AC at the monitor power connector.

[SegaAges]

Originally Posted by Ken Layton

Trace/follow the wires back from the monitor. There should be approx 120 volts AC at the monitor power connector.

Ok, cool. My roommate has a multimeter that I will bust out when he gets home to test it out.

EDIT: multimeter is giving a reading of 0 ac volts. I tested at the actual pins. Is that the place I should be checking at? What I did was put the multimeter underneath the board to get readings from the bottom of the pins.

I did, just for fun, set it to dc to see if anything was happening for a reading, and it did give me a dc number, but ac is zero