CRT replacement for Tecmo Kyotaro 29”?

[Takosuke]

Hello, I found a Tecmo Kyotaro can for sale locally, and the cab is in great condition, except for the CRT. The image is blurry, and offer a superb tone of green/yellow with the lower part being purple. Ugh.

Is the tube easy to replace? What would be good alternatives to look for?

Still debating if worth purchasing or pass on it.

Any advice would be much appreciated!

 

[Mitsurugi-w]

Blurry probably isn't the tube itself and the color issue can probably be fixed with a degausser.

 

[Takosuke]

Ah thanks, I never degaussed a screen before outside of my PC monitors back in the days and I had a button for that :p

What would be the method? Degaussing wand?

In case this does not work, any idea on replacement?

 

[Takosuke]

Here is a video of how it looks sorry for the quality.

 

[Mitsurugi-w]

Yea try degaussing it first. A wand works fine.

 

[frsj8112]

@Takosuke
Cool cabinet, is the monitor rotatable?

 

[Takosuke]

Yea try degaussing it first. A wand works fine.

Cool, Thank you

@Takosuke
Cool cabinet, is the monitor rotatable?

It is, Manually.

Tecmo Kyotaro 29”

 

[Takosuke]

So I bought the Cab

Kinda sad to see it's a Wells Gardner K7400 inside and not the Nanao MS8 series that Hard Candy and some Wiki list in it.

But, turns out the monitor was not as bad as I though it was when I saw it at the seller's home, he just did not have it configured properly. After adjusting the nods and degauss, it looks way better! IT will do for not, but I will keep an eye on it and maybe replace it one day

Progress tracked on this forum and on my repair blog Thank you!

 

[nem]

K7400 is the best monitor Wells-Gardner ever made. Great picture quality. Replacements parts are easily found if you have problems down the line. Not a bad find at all!

On the other hand if you had found a generic Chinese chassis, that would have been sad!

 

[RealMFnG]

Great great cabinet. I wouldn't have even batted an eye if I could pick up that cab for a decent price. And it looks to be in fantastic condition. As for the K7400, the picture is superb. But the learning curve to repair them is quite high. If you ever have to recap that monitor, the chassis has 3x the amount of caps in than the K7000 (made by Wells Gardner and is the most ubiquitous monitor of all time). Not fun. Not a big deal if you are the type to just send off a chassis to a pro for repair/maintenance however.

More Tecmo Kyotaro porn pics please!!

 

[Mitsurugi-w]

Great monitors when they work. Can be a real pain to diagnose when they stop. Especially now that they are outliving their flow charts.

 

[Takosuke]

A few follow up questions after spending some more time with it

1) @Mitsurugi-w or other admins, can you move this post to the "Monitor Help" section? I realized that i posted it in the wrong part of the forum. Or maybe I can cut the folowing questions and create a new thread there, more general than "replacing the CRT"

2)Is there a way to shield in some way the screen from magnetic interference? I moved the cab all around my apartment, and no matter where I place it (unless it's in the dead center of my living room,in a very specific position, I got screen discolorations on some side or corner of it that is more or less annoying (You can see it here in the lower right corner). This is actually probably the best result I can have, and it's really annoying when playing games like Puyo Puyo.

3) One solution could be to place a neodymium magnet close to the impacted zone to counter it, but I don't know if it would hurt it more than anything long term since it's usually not good to place a screen near a magnet like speakers...

4)The control panel seem to do some weird interference with the monitor. It's not fixed to the cab as it's missing pieces (screws/bolts on the hing and bars for the key mechanism), and if when it's in there, the screen brightness changes once in a while (a little bit brighter, a little bit dimmer, for a flicker of a second). I noticed that if I take it off and move it away from the cab on my lap, the flicker stops. I moved the remote board away from there but it does not seem to come from it. Any idea?

5) I sometimes have for a second or two an hourglass effect on each side of the screen. I can appear in the middle of playing, and disappear on its own or if I turn the cab on and off.

6)Very rarely, I see a little line of interference on the screen. Not very bothering as it's rare, but concerned of what it could be.


Other than that the quality of the image is pretty good overall, so I'm not sure I want to go the way of a full recap or changing the flyback or other if I don;t need too. That part scares me a bit, but I'll do it eventually I guess.


Thanks!

 

[nem]

2)Is there a way to shield in some way the screen from magnetic interference? I moved the cab all around my apartment, and no matter where I place it (unless it's in the dead center of my living room,in a very specific position, I got screen discolorations on some side or corner of it that is more or less annoying (You can see it here in the lower right corner). This is actually probably the best result I can have, and it's really annoying when playing games like Puyo Puyo.

The monitor should have a degaussing coil around the tube. Depending on how it is wired it's supposed to kick in either every time you turn on the cab or when a separate degaussing button is pressed. Usually the button can be found where the test and service buttons are. Look for this button and start from there. If you find one, press it when the monitor is on and you should hear a "thunk" sound and the screen will shake for a second. Usually on the second press the discoloration will clear away. Always wait 10 or so seconds between presses.

However, since your monitor has been swapped, it's more than likely that nobody wired the degaussing button (if there is one). Read through the K7400 manual and find out where you need to connect one.

3) One solution could be to place a neodymium magnet close to the impacted zone to counter it, but I don't know if it would hurt it more than anything long term since it's usually not good to place a screen near a magnet like speakers...

Really bad idea, don't do this.

4)The control panel seem to do some weird interference with the monitor. It's not fixed to the cab as it's missing pieces (screws/bolts on the hing and bars for the key mechanism), and if when it's in there, the screen brightness changes once in a while (a little bit brighter, a little bit dimmer, for a flicker of a second). I noticed that if I take it off and move it away from the cab on my lap, the flicker stops. I moved the remote board away from there but it does not seem to come from it. Any idea?

Possibly a grounding issue. Although personally, I think it's just the monitor acting up and the control panel has nothing to do with it.

5) I sometimes have for a second or two an hourglass effect on each side of the screen. I can appear in the middle of playing, and disappear on its own or if I turn the cab on and off.

Either a bad pot, cracked solder joints or most likely aging capacitors. Look in to replacing the electrolytic capacitors on the monitor chassis.

6)Very rarely, I see a little line of interference on the screen. Not very bothering as it's rare, but concerned of what it could be.

Again, possibly a grounding issue. Could be related to the PSU as well.

Other than that the quality of the image is pretty good overall, so I'm not sure I want to go the way of a full recap or changing the flyback or other if I don;t need too. That part scares me a bit, but I'll do it eventually I guess.

There's no reason to change the flyback. Recap on the other hand is a good idea and worth doing on a Wells. It's also pretty easy to do yourself.

 

[RealMFnG]

Getting better with the multi-quoting and bulletizing @nem!

 

[Takosuke]

Thanks for your answers @nem!

2)Degauss:

The monitor should have a degaussing coil around the tube. Depending on how it is wired it's supposed to kick in either every time you turn on the cab or when a separate degaussing button is pressed. Usually the button can be found where the test and service buttons are. Look for this button and start from there. If you find one, press it when the monitor is on and you should hear a "thunk" sound and the screen will shake for a second. Usually on the second press the discoloration will clear away. Always wait 10 or so seconds between presses.

However, since your monitor has been swapped, it's more than likely that nobody wired the degaussing button (if there is one). Read through the K7400 manual and find out where you need to connect one.

The monitor indeed has a degauss coil, but even though it seems to be plugged in, I don't really hear the familiar sound of a degauss when powering the cab on. I would probably need to take the chassis out and check if something is wrong with this.

Here is a picture for info https://imgur.com/a/uYU5h5m

No button for manual degauss either, after looking at the chassis and the manual/documentation I found online for the 27" K7400.

I did use a manual Degaussing Coil from GC Electronic (big sturdy round one) a couple of time when I got the cab, and again tonight (usual start far, get closer with concentric cycles and then away from the screen in the same motion before turning it off), but that does not seem to have any effect on the discoloration.



3)Neodymium:

Really bad idea, don't do this.

Yup, I saw it mentioned on a couple of forums but that sounded like a bad idea.


4)Brightness flicker

Possibly a grounding issue. Although personally, I think it's just the monitor acting up and the control panel has nothing to do with it.

Weirdly enough, It definitely stop when I remove the Panel. How would I go about testing to see if it could be a ground issue?


5)Hourglass

Either a bad pot, cracked solder joints or most likely aging capacitors. Look in to replacing the electrolytic capacitors on the monitor chassis.

Seems like I have no choice but to do a recap Scary but I could give it a try (the scary part is taking think apart, never discharged a screen before even though I read a lot and watched videos about it).
I found some cap kits, any feedback on the sites:
- Arcade Part Repairs (Cap Kit + 270uF 400V)
- Arcade Buffet (Cap Kit no filter cap)
Any other place?

6)1 line Noise/interference

Again, possibly a grounding issue. Could be related to the PSU as well.

Should I go ahead an replace the PSU by a brand new Suzo Happ? I don;t mind paying 40-50 bucks to be safe...

There's no reason to change the flyback. Recap on the other hand is a good idea and worth doing on a Wells. It's also pretty easy to do yourself.

Good for the flyback It seems like recap/retrace is the way and unavoidable. I wish I had someone nearby that could help me removing the cathode/replacing it, as I must admit it scares the shit out of me


Thank you!

 

[nem]

The K7400 is so new that it has a bleeder circuit for the anode. Just wait a few minutes after turning it off and the anode is safe to pull off.

This said, I always manually discharge every monitor when taking of the chassis even if I know there's a bleeder circuit, because it's a such a small thing to do.

https://wiki.arcadeotaku.com/w/How_to_discharge_a_monitor

Start with the recap. It's possible it could solve all your problems.

I have never used a ready made cap kit, so I can't help you there. However, the K7400 is such a common chassis that most likely both options are fine. Alternatively, you could always map out the needed caps yourself and just order them from Digikey or some other parts supplier.