Another K7000 in crisis

dskinchen

New member
Joined
Mar 1, 2012
Messages
6
Reaction score
0
Location
Florida
First, about me: First post--enough electronics experience to know the basics but before now, little monitor experience.

Have a WG 25K7193. Recapped when I got it and it worked good for a couple years, then died. Blank screen. Then the flyback went. Got a cap kit, flyback and hot from Bob Roberts. Installed all and back to just shutdown.

Started reading here and got Randy Fromms flow chart. I have neck glow. I have sync. Turning up the screen control I get horizontal scan lines so following the chart, I checked b+ = 129v & 155v

OK, so further reading I've pulled r84-86 and they checked out fine. R103 good, R301 good. Pulled C55-good. Found R89 loose and resoldered. Reflowed everything. R101 seemed loose so i got that down too.

I haven't pulled D10, should I? What else? I'm really getting frustrated... Thanks for any guidance and don't be shy about details on how to "check" things 'cause other than some obvious stuff (diodes, resistors and the like), I don't know a lot.

Thanks again, David
 
If you have neck glow, the HV section is fine. You either dont have B+ on the neckboard, or the 1mf coupling caps near the input section are in backwards.
 
make sure the trace from R101 and C23 connect to the jumper on the back side of IC2.

the jumper is between R57-R39.

if that is good pull D10 and see if you get a pic if you do then you have either cold solder joints on the VR or it is bad.

re-flow the VR and H.O.T as well.

also reference the sticky at the top or this section for more tips on what to do.

Peace
Buffett
 
So, let me get this straight:

You have a B+ of 129 - good.

You have neck glow - good.

You turn up the brightness and see retrace lines - good.

You have sync - good.


So - what exactly is the problem? Sounds like it's working...
 
Thanks guys. The sticky is where I started but that doesn't mean I missed something. I'm off to check things out. Back shortly...

Modessitt, one problem, no picture. I've got a mame cabinet and everything works up to p2.
 
Update:
B+ on neckboard 129v
All caps oriented correctly.
R101/C23 trace all the way to H. Hold
D10 removed, still no pic.
Reflowed HOT and VReg just for gigs.

I'm guessing it's something stupid, I just can't seem to find it...

Add that C36 reads out as 6300pf. I assume that's close enough for govt. work?
 
Last edited:
Okay, if you have retrace lines when you turn up the brightness, but no video when connected to a game, then I'd check along the video ground path. No ground connection between the monitor chassis and the game board will give you no picture.

Other than that, trace the color voltages from the video input pins through to the input pins on the IC - to make sure they get that far - then make sure you have it on the output pins all the way to the neckboard, then through the pots and drive transistors to the sockets. Somewhere you should figure out what is causing no game pic....
 
Okay, if you have retrace lines when you turn up the brightness, but no video when connected to a game, then I'd check along the video ground path. No ground connection between the monitor chassis and the game board will give you no picture.

Since I'm running a Mame cab, I assume the same applies. I'm using an ultimarc vga card with r,g,b,-,& h&v sync so I need to verify the ground is connected, correct? I checked before but will recheck.

Other than that, trace the color voltages from the video input pins through to the input pins on the IC - to make sure they get that far - then make sure you have it on the output pins all the way to the neckboard, then through the pots and drive transistors to the sockets. Somewhere you should figure out what is causing no game pic....

So from here, meter the traces from r,g,b input pins through the circuit and look for a failure. OK, that makes sense. Thanks for your guidance!
 
Whoa - you're using this with MAME and an ArcadeVGA card? There could be lots of issues with that setup. You need to verify the monitor with a regular arcade signal first. It may be fine...
 
Modessitt

The pc works fine. I sent the card back to Andy and he verified it is working fine. I get perfect output on the dvi output of the card to a pc monitor and the card to monitor cable checks out OK. I'm not sure what else to check.

While I'd prefer to have a test signal generator to test the monitor, I don't have one and I don't have a working arcade game board. Keep in mind the whole system worked great for about two years before it just stopped working. Of course I'm open to ANY suggestions...
 
OK, so I dug out my Neo Geo MVS 6 board. Fired it up, and whoa! WG works fine. Soooo... something else is wrong.

Mod, you were so right. I'm sure you get that a lot. On the upside, my new fly and recap install went perfectly and I learned a lot. On the downside, my mame machine still doesn't work. Back to the drawing board... A huge thanks to everyone that offered help. You guys really know your stuff!
 
Back
Top Bottom