WGK7193- need troubleshooting guide

[Darmonde]

Hi all,

I recently picked up a cabinet with a WG7193 monitor.  Everything is arcade parts.  The red would go on and off on the monitor, the screen flickered, and there was occasional pop noises from the flyback.  Everything pointed to caps and flyback troubles (they were all originals), so I ordered and installed them (ordered from Happ Controls, they are local for me so I was able to drive over and pick it up).

After installation, I am having the same problem that many have had before me.  The screen now shows close to nothing (looks like the 'screen' control is set too high).  I'm able to turn down the screen and at one exact point am able to see very very faint shadows of the graphics, and the sound still works as before, so it's almost definitely the monitor.

From the posts I've seen, there is a 'wg7000 troubleshooting guide' somewhere, but I wasn't able to find it.  Does anyone have it, and can link me to it?

The other question I have is almost hypothetical.  I changed all the caps and the flyback, and the monitor went from working decently to not working at all.  I really feel like there could be something wrong with the job I did.  I've triple checked my cap orientations, but is it possible that a  bad cap or incorrectly installed flyback could be causing this screen problem?  The soldering job on the board wasn't the best, but I didn't find any dry connections.  Only after my first try did I reflow a few joints, but I'm reluctant to continue messing with things because I feel like I may just cause even more problems.

Lastly, if my work was done correctly, then according to what I've read, the problem is probably with:
A) solder- reflow everything  =(
B) C36 replace
C) HOT replace
D) blanking IC?

I almost wish that I didn't throw out the old flyback.. I'm getting paranoid that I somehow got a bad flyback (because other people who have had this problem fixed it by getting a new flyback).  Is it worth it to order another flyback to see if the new one I installed was bad?

Thanks in advance.  I'm hoping that with the troubleshooting guide, I'll be able to test for sure my other parts (I really don't know how to test many things right now).  If anyone has any advice, please let me know!  Also, if there is any info I left out that might help please let me know.

[Ken Layton]

The replacement flyback has two wires that connect to the neckboard. Did you connect them correctly? The thicker gauge wire of the two is the focus wire which connects to the tube socket. The thin gauge wire is the screen voltage wire.

Have you checked the solder at resistors R89 and R101 very closely? They are prone to tarnished copper under the solder so the solder may look ok, but not making electrical contact with the foil trace.

The 719x is merely the 25" version of the k7000 and uses the same troubleshooting flowchart. Randy Fromm has it on his site, but I think it's not part of the pay section of his site now.

Use the 25k7191 schematic in conjunction with the k7000 manual.

Visit this site for more info:

www.jstookey.com/arcade/WG_25k7191/

[Darmonde]

Ken,

you are a genius, and I am an idiot!  The old flyback had two wires, red, and black.  The new had red and white.. I matched the two reds, but your statement about the gauge of the wires made me realize that the wires were transposed!  I hope that anyone else with this problem sees this thread and follows your advice.

It's 1am, and I could not sleep because I thought this might be my problem.  So I'm up, took my cab apart, saw that the wires were switched, and now the picture is showing again!  I cannot express how excited I am this thing is working again.  I'm lucky I didn't destroy my monitor with that mistake.

I'm missing red on the monitor also, but I remembered seeing an old thread with the same problem, searched, and found this quote from you:

"The k7000 series is well known for cold solder joints on the main circuit board particularly around the flyback terminals, horizontal output transistor and the video input connector. I'd bet the pins around your video input connector are cold soldered causing your "intermittent red" problem."

I shook the video in connector, and the red pops in and out.  Your advice from 2 years ago is still great, and now I can sleep knowing I just need to reflow the video in and my monitor should be whole again.

I'm really tired, but had to let you know how big a help you were, and thank you!

[Ken Layton]

Glad to have helped. 

A good rule of thumb regarding flybacks is the replacements will often have different colored wires than the original one.