19k7000 corrupt graphics, sync problem?.

[ac3]

I think this monitor is a 19K7681 but I had another 19K7000 at the same time I had this one I remember swapping the chassis about so Im not 100% sure. The problem is the image is all distorted, I think it is a sync issue? although the image isn't scrolling and adjusting v or h sync this is the best I can ge it. I have ruled out the game board, tube and wiring so I know it is a chassis fault, has anyone seen anything similar to this before?.




The sync wire is attached to the 3rd pin, pins 2 and 3 were jumpered which is why there is a loose wire.

Any help is very much appreciated.

[SirPeale]

Zenith K7000, sync issue for sure.  Probably some kind of configuration issue with wiring.  Have you tried the sync wire in both the 2nd and 3rd position?

[ac3]

Yes I tried it on 2nd and 3rd pins, the 3rd pin gave the 'best' picture, are you sure it is a Zenith? I thought Zenith chassis had a strange flyback with 2 wires going to the anode cap?.

[grantspain]

not same chassis but this week i had to wire up a u5000,it used the video ground and sync on the plug with the rgb and also i had to link vert and hor sync otherwise i had a picture like yours

[Kevin Mullins]

What game is it?

Have you checked something simple like the solder joints on those input header pins?
A cracked sync or ground pin will cause this sort of problem.

A K7600 is medium resolution, so if you swapped any chassis around you kind of need to know what you swapped it around with. 

[ac3]

The game is super street fighter 2, I've been over the chassis checking for cold joints and also checked the caps. SirPeale has reminded me that the one I swapped it with was a Zenith which I got rid of a long time ago, so this is the original chassis (19K7681) as written on the frame. I've also already tried jumpering the two sync pins on the end with no luck.

I'll try what grant has suggested next and get back to you all.

All that happened from moving the sync wire was it would no longer sync, also the 2 ground pins are connected on the chassis so it doesn't matter on this board which one you plug it into. I checked C22 and Q7, could IC2 be the problem? I dont have a spare to try.

[lilshawn]

street fighter 2 is standard resolution game. so it should work with the k7000 chassis.

it doesn't look like a zenith made one... if it was it would have one of those weird voltage multiplier things on there and it looks like the flyback goes directly to the tube. besides, the "zenith" k7000 and the WG k7000 are identical c'ept for the flyback... the zenith branded tubes needed a higher high voltage and focus voltages.

[grantspain]

i also mentioned i had to link vert and hor sync on the connector to get a lock

[SirPeale]

Not all the Zenith chassis had the doubler, and some regular WG chassis do.  I have one that has it, and it's made by WG.

The colour of the PCB is a giveaway, though I've read that there are some WG chassis that are brown.  The best way to determine this is to check the layout of the flyback pins.

[ac3]

i also mentioned i had to link vert and hor sync on the connector to get a lock

I tried that too, same screen of broken graphics just worse as it scrolls too.

[Kevin Mullins]

The colour of the PCB is a giveaway, though I've read that there are some WG chassis that are brown.  The best way to determine this is to check the layout of the flyback pins.

Some of the older WG's were that brown color, like some of the older P447's.
They also don't usually have the 50/60Hz pot.

You can look around the middle of that chassis for a "P447" or "P538" type number.
The Zenith made chassis do NOT have any kind of marking on them.

@ac3 -
So you have tried adjusting the Horizontal Shift and all that?
Did this chassis EVER work with this game?
What is the "Pxxx" number silkscreened on that chassis? (will be something like P823, P447, P538, etc... usually found in the middle area of the chassis pcb itself)
 
To the best of my knowledge Super Street Fighter 2 is a standard resolution game.... a K7600 is typically a medium resolution monitor.

[grantspain]

if that is a 24khz chassis then that would explain it

[ac3]

if that is a 24khz chassis then that would explain it

It's not I've never had a 24khz chassis. I've tried adjusting all the pots on the remote board and the ones on the chassis including 50/60hz. The chassis did work when I first got the monitor a couple of years ago it's been stored away since then. I'll check the number(s) on the chassis and get back to yous.

If some how I ended up keeping the Zenith tube could that be the problem? are the yokes different spec? I am guessing a out of spec yoke wouldn't give this sync problem though?.

EDIT:
Finally sorted although I don't know how. I moved the hori jumper on the chassis to one of the off center pins so maybe it wasn't connected properly? I also adjusted the width coil but that was about it. It was very hard to get it to sync, only one of several boards I tried synced then I swapped back to sf2 and the sync was off. I am thinking the sync pot on the chassis might need changing as it very sensitive. Not that it matters now but the board has P447B printed on it next to the lopt. Thanks to those who posted for all your help, I am very happy to get this working as it gives a fantastic picture.