WG K7193 Problem.....AGAIN!

[GuinnessGuy74]

Ok, so I replaced the shorted diode.......power up......no fuse blowing......yeah!

Hook up RGB, ground and vsync.......messed up picture. All i see is scramble (messing with all the controls...vhold etc does nothing) and hear a low, high-pitched whine. This whine goes away when the vsync lead is disconnected. I have attached 2 pics of Ultimate Mortal Kombat 3 (trust me, it may not look like it but it is). They are the first few screens. Second one says Midway Presents......

Any thoughts as to what the problem is.....I thought once it powered up without blowing fuses it was going to be fine.......I am looking forward to your answers!!

Thanks again guys,
Jim

[GuinnessGuy74]

Fixed the problem.......had a bad vsync wire!

However there is a slight wave in the picture....mostly noticeable in the corners. I doesn't really affect the image, but it does affect the eyes as it is rather distracting. I cant remove it with any of the six controls on the remote wire harness.

Anyone know what causes this? I am sure you guys will rattle off a list of 900 components it COULD be..........but I am asking for it anyway!!

Thanks,
Jim

[Ken Layton]

Could be a bad capacitor in your game power supply causing your wave.

[GuinnessGuy74]

Hmmmmm....interesting Ken. I'll give it a look. Do you think it could be a problem on the board itself? I did have to replace a resistor that was broken off to solve an graphics address problem. Think I might have screwed something else up?

I'll have to find another power supply to test the board with, and then see what happens from there! Thanks a bunch...not sure where I would be without you guys..........

Jim

[GuinnessGuy74]

Will these problems ever end??? I have discovered it is NOT a bad sync wire. It is something else. I can leave the game running, come back and it is fine. But if I turn it off and then back on (or hit the reset on the pcb) it is back to being messed up like the pics above.

When I leave it off for a little bit and turn it on.....presto, picture is good (albiet except for the slight wave, which now that I have looked at it long, looks more like up and down waves and not really a "hula", but maybe its an optical illusion). I know I keep bugging you guys, but do you have any ideas on this new development? Bad caps maybe? Interference from somewhere? I dunno...... Let me know what you come up with!

Thanks as always,
Jim

[menace]

well start with a cap kit--you likely need one regardless if its related to the problems you are having--it will be a very easy way to eliminate that from the troubleshooting phase.  Check your pots as well as your headers (where your connectors get plugged into the chassis ) for cold solder joints.   Also when you get a picture that is relatively stable give the pots a small twist in each direction and not any changes--if there are no changes you can try moving that pot by larger amounts--if still no change the pot could be bad. 

Have you looked at randy fromm's flowchart for this monitor?  it will also help with any troubles you may encounter.

[GuinnessGuy74]

Thanks for the reply. I ordered a cap kit from Bob last night thinking exactly like you said.....could be the problem, but can't hurt if it isn't.

Turning the pots do change the picture, both small and large amounts.

I used Randy's flow chart for the "hula" effect. I have gotten to where you turn up the screen control (since all voltages were correct)  and look for a white screen with diagonal white lines through it. I dont get a white screen. I get a greenish screen with lines, but I can clearly see the game running in the background. Just so I am correct on this, I turn the knob on the flyback, that is the screen control right? Do I need to adjust the brightness as well? Either way, that is as far as the flowchart takes me because the next step asks if the CRT Heater is glowing, and it is....hence end of flowchart.

Hopefully the cap kit will solve the problem....I am also looking for another power supply to test out Ken's idea.....Any thoughts in the meantime are more than welcome!

Jim

[Will]

My wg 25k71 had a wavy problem at the top as well and it looked a bit blurry.I changed the caps and most of the fuses and had to resolder alot of worn solder joints and replace some wires going to the neck board.After I did all of this I had a great picture besides some slight burn in which I believe there is no cure for it.Its a great monitor when properly tuned up.Good luck!

[Ken Layton]

If you don't have a fresh cap kit in this monitor then I'd get one in their pronto! While you have that chassis out to install the capkit, be sure to inspect it closely for numerous bad solder joints. Clean off the flyback and inspect it closely for any signs of cracking (a sure sign of impending failure). The original flybacks on these are failing so much now that it's worth it to install a new one anyway and this monitor will be good for another ten years.

[GuinnessGuy74]

Thanks Ken, I am going to install the cap kit as soon as it comes. took the chassis out again and I am looking over the board for bad joints. I will let you know the results sometime next week!

Jim