Nanao/Kaga (KB240112) - Figuring out inputs so i can fix it.

[GF_74]

I have an old cabinet (Video Village - NZ) with a Mitsubishi 19” tube and what I think is a Nanao/Kaga monitor board, but I cannot be sure (labelled KB240112). I have included some images of the main board (side on i am afraid) and a simple schematic that was inside the cabinet.

Can anyone confirm what board this is?

The labeled inputs are:
1)   R -> Red
2)   B -> Blue
3)   G -> Green
4)   Blk -> Video Grnd
5)   HD -> ?? Horizontal deflection ??
6)   VD -> ?? Vertical deflection ??

So, hooking it up, I can get a picture (messy) with one of HD/VD connected to the JAMMA video sync, but if I connect the other one or both I get nothing on the screen. It does need a bit of work as I think it has partial vertical collapse.

If i get a decent picture i will post the resultant screen mess.

Any help would be appreciated.

Thanks,

[grantspain]

r,g,b are obvious but which wire have you connected to video ground and are you using the correct video ground

[Pac-Fan]

I have three (2x 13" and 1x 19") of this identical monitor. I have one connected to a Turbo mini right now. I will double check the wiring I used and let you know.

If you're getting a jumbled mess, you might want to adjust the horizontal frequency pot (VR501), and might also need to tweak the vertical hold (VR401) afterwards.

Looks like someone de-framed the monitor and directly screwed the flyback cage and main bottom frame that holds the chassis to the side of the case. I had to do that too to get it to mount in my Turbo mini as the original monitor had long since been removed.

[GF_74]

I have hooked up the video ground from the Jamma to the ground on the monitor chasis. i have not yet fiddled with any of the pot's, but will play tonight.

Grant.

[GF_74]

I set it up and run the current rig and tweaked as many knobs as i could find. Mostly to no avail. I have taken a snap showing the best i could get. It would appear that i have a long road ahead of me to get this one going.

It would also appear the hooking up the video sync to either HD or VD does not a lot.

I guess it is down to capacitor replacement, checking for dry joints or starting to replace components  .

If you have seen anything like what it is the picture and can point me in a direction please do.

Thanks.

[Pac-Fan]

That's a new one. You have green splines everywhere.  I didn't see any other color than green in the pic, so that could mean you have dead guns or bad transistors or bad solder joints on the other colors.

What happens if you turn up the screen control (or brightness) -- do you get a flood of green or a flood of white?

Since the center of the picture is primarily a horizontal line it looks like you have some significant vertical deflection collapse.

I would definitely start with a cap kit and check for solder, and then see what you get after that.

[GF_74]

If i adjust the brightness i do not get a flood of anything. The shot was the best that i could get.

If i adjusted one of the control (cannot remember which one) i did managed to get some flickers of blue or white, so hopefully the blue and red circuitry is doing something.

Oh well, time to get out the soldering iron.

[qrz]

i assume ur pic is dark everywhere but the lines.... might try agn- minus the flash.
 meanwhile , the problem may in vertical deflection .
complete loss of vertical would result in a flat horiz line .
since there is some deflection, there is activity in the vert . check components .
also check the yoke  . the vert yoke consists of two parallel windings . if one winding becomes open ( usually loose/broken wire)  the display will have a similar curve .
have seen this < 10 times in the last 20 yrs , so NOT a common failure . but still worth checking.....

qrz

[GF_74]

I did attempt without the flash but could not keep the camera steady enough to get a good shot. Just take my word that the remainder of the screen is black regardless of the brightness level set on the pot.

Do anyone have a schematic for this so i can target the vertical componentry rather than trying to check the lot?

Thanks.

[qrz]

finally looked at ur first pics...this monitor has some age to it - though clean !
 t-o3 as the hot and vreg puts it in the '80s.
as such, the vert output will likely be a 2 xistor pair rather than a single IC....
def suggest 1st , get some good lighting , magnification and inspect that yoke !

meanwhile, will see if can locate a print......?

qrz

[GF_74]

I have pulled the monitor board out and taken the following

Set 1

[GF_74]

Set 2:

I also tested the yoke resistances and got 0.2ohm (Brwn/Yel) & open circuit (Red/Blue) .

[Pac-Fan]

I also tested the yoke resistances and got 0.2ohm (Brwn/Yel) & open circuit (Red/Blue) .

Brwn/Yellow is the vertical deflection and .2 ohm is way too low. I don't recall if this is a high or low impedence one (I'm guessing high off the top of my head), but in any case .2 ohm is too low for either winding on any yoke. 

However, Red and blue are your horizontal deflection and that should read between 1 and 3 ohms. But your pictures show that you do have complete horizontal deflection, so I'm wondering if your meter is not working correctly or you're not getting a clean contact point to measure from.

I promise to take some time this weekend and get you readings off of my identical monitors (I've got three of this exact unit which from what I read is the first Nanao version chassis made) to this and let you know the results and see if it can help.

[GF_74]

I double checked the resistances and got the following.

Red/Blue: ~1.8 ohms - so i guess this is ok.
Brwn/Yel: ~1100 ohms - unsure about this one.

Most of the windings look ok, there is a single copper that is broken, but jumpering this does not seem to affect the resistance.

GF

[qrz]

I double checked the resistances and got the following.

Red/Blue: ~1.8 ohms - so i guess this is ok.
Brwn/Yel: ~1100 ohms - unsure about this one.

Most of the windings look ok, there is a single copper that is broken, but jumpering this does not seem to affect the resistance.

GF

last line is the key .  and bet that is on the vert !
1.1k ohms is way too high for a deflection coil .. change that puppy !

qrz

[GF_74]

 

'Change that Puppy' implies that i have a spare puppy, which i do not.

Know anything about tube/winding repair 101 ??


GF

[qrz]

'Change that Puppy' implies that i have a spare puppy, which i do not.

Know anything about tube/winding repair 101 ??


GF

have a prt # off the yoke  ??

yes , i have wound coils ( RF/IF) .  but , NOT a deflection yoke .  wouldn't even THINK of trying it - (shudders)
there is special geometry involved due to the shape of the core ....
if can't source it, u could try a elect motor shop to see if they might be willing to give it a go. 

qrz

[GF_74]

Given your grim advice i decided to go the cheap way and just solder the broken wire back together. Doing this gives me the following resistances.

Red/Blue: ~1.8 ohms
Brwn/Yel: ~40 ohms

i thought that was close enough so plugged it all back together and through a game on it. The good news is that i have both horiz & vert deflection 

Bad news is that the picture now resembles a intermittent snow storm. Just sparse streaks over then entire screen with mostly black in the background. Adjusting the knobs gives me a very 'interlaced' blob, but no real picture.

If needs be i can take a picture of it.

Thanks for the advice to date.

GF

[qrz]

might be interesting to see what you have ...

it is possible to sub a standard tv yoke - since low res  . use from same size screen.

fyi, had a 13" tv/dvd combo come in with a similar pic.  cause was the set had been "watered" and
improperly dried . the resulting corrosion opened several wires on the yoke as well as minor pcb damage.
the yoke was NA from the mfg (typical of Chinese junk ) even though only 2 yrs old.
found a 1978 13" in the junk heap .....yes , 1978.
 installed and a few adjustments later , working as new .

qrz