Help with Wells 25K7401 in Radikal Bikers cab

[xrayarcade]

Ok so I have some issues with a monitor in a game I am working on. I have zero monitor repair skills, but wondering if this is something super simple, or if this is just one I should send out to a pro or at least try a full cap kit on first.

1) The blue works SOMETIMES. See attached video. If you bump the machine, the blue comes back in. Sometimes it stays for a bit. The jank job that they did with the molex connector on the board could certainly be responsible. See that picture below as well for a laugh. They had also literally just jammed the pins for the power to the monitor in to the existing molex connectors on the monitor board - I actually got the correct molex connectors for these so they're no longer just electrical taped pins jammed into one side of the molex. But then I noticed this little workaround on the video signal to the board.

2) The monitor shuts off completely sometimes, then turns back on later. Then turns off again. It's not consistent. Seemingly random. Will play for an hour, then just stop. Then if you turn it off and wait a bit, turns back on fine. So it's not totally dead. They also used what appears to be like a lamp power cable to run power from the iso transformer to the monitor. It's thick enough wiring, so presumably this is not the cause of the issue, but if so, I could easily replace that as well.

3) The screen shakes vertically. It isn't the V hold, that is fine, but if you go to the test menu and look at the monitor test screen, it's like it's shaking up and down a tiny amount, very quickly, all the time.

Any help would be appreciated here.

Radikal Bikers

2 new items added to shared album

photos.app.goo.gl

 

[mecha]

you need to provide more pictures, your text description of the wiring and plugs doesn't make any sense to me. the blue going in and out could be wiring related, but the K7400 has one of those neckboards that get super hot and will do a number on the color drive transistor solder or solder pads. I haven't seen that happen in a very long time, but it did happen to me years ago. the shutdowns could be cap related, particularly if you're still running the near 25 year old original caps. also the K7400 doesn't require an isolation transformer, I don't much understand why any modifications needed to be done to the already existing power wiring the game came with.

I deal with hillbilly hackery like that every single day and it's starting to really wear away at me now.

as is evident here, not everyone can be a rocket scientist.

 

[xrayarcade]

Oh the hillbilly hackery on this one is bad. Sorry my description was weird, but imagine if you had one half of a molex connector wired properly, instead of wiring the other half, you just plugged two other wires with pins (but no outer molex casing) into them, and just electrical taped it to keep it in place. That's what was done to get power to this monitor. They probably scavenged shit from this to fix another cabinet or something. It doesn't help that this is a dedicated Radikal Bikers which has a shitload of unused plugs all over the place (uses a 4 player jamma harness despite being a 1P game)

Anyhow, I fixed this - I found the connect other halves of the molex connectors needed and wired them up properly, but it's still using what looks to be an old brown 2-wire lamp power cable. I don't THINK that should make a difference.

In the picture it looks like that they just used two different connectors to get the video signal plugged into the board rather than the proper one.

 

[mikenes75513]

I have had color intermittently go out due to bad solder joints where the signal is plugged in. Mecha will tell you to reflow them (actually surprised that wasn't the first thing he said). The two connectors to the signal header is pretty standard. 6 + 3. The fact that you have pin 6 used as well as 2 and 3 on the second one is strange to me, but I dont remember what pin six is so I can't say if it will cause issue.
I have a different k7203 with a vhold bounce its like the pot just can't go far enough. I haven't dug too much because it is quite intermittent. But it happens more if I move the pot off the far edge and then it will slowly loose sync. Does this one have a remote board with other potential problematic solder where the remote plugs in?

 

[mecha]

I have had color intermittently go out due to bad solder joints where the signal is plugged in. Mecha will tell you to reflow them (actually surprised that wasn't the first thing he said). The two connectors to the signal header is pretty standard. 6 + 3. The fact that you have pin 6 used as well as 2 and 3 on the second one is strange to me, but I dont remember what pin six is so I can't say if it will cause issue.
I have a different k7203 with a vhold bounce its like the pot just can't go far enough. I haven't dug too much because it is quite intermittent. But it happens more if I move the pot off the far edge and then it will slowly loose sync. Does this one have a remote board with other potential problematic solder where the remote plugs in?

I didn't suggest signal header because blue isn't one of the outer pins that would take the most abuse.

U5000/U2000/K7400/K7500 are all able to take sync on either positive or negative sides. Williams/Midway figured out they could save 3 cents per game if they just use the 6 pin arrangement instead of the 10 pin. also the Hantarex Polo and Neotec monitors all run 6 pin positive sync arrangements too, so they didn't have to make adapters anymore. this along with the fact those were all switching mode power supply monitors that didn't need cabinet isolation transformers anymore would present problems if you're a hillrod and replace the better monitor with a K7000 because you have little understanding of how to maintain games. ironically, nobody knows how to fix K7000s properly either. that's my real life struggle as a game technician, dealing with all of the above. LOL

the Radikal Bikers hardware is notable for being complete garbage to work with, the vertical jitter thing could be in the hardware. those develop a lot of video-related failures, but I've never heard of that one.

 

[mikenes75513]

I didn't suggest signal header because blue isn't one of the outer pins that would take the most abuse.

Never thought about that. The one monitor this was a problem blue was the only color that worked.

 

[mecha]

probably a good time for a PSA about signal plugs, cut the little friction lock nubs off. you shouldn't have to fight to plug or unplug those. human solder shouldn't break down like the robot solder they came with at least.