My DK Jr. has a slight wave, and I just realized that the power cord has no ground

JamBurglar

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My DK Jr. has a slight wave, and I just realized that the power cord has no ground

I've got this DK Jr. (now a Mario Bros) cab, that has always had a slight vertical instability. It's just a little wavey, nothing too noticable. I've had various PCBs in this cab and the wave is always present. My B+ appears to be stable at 108.1.

I did a search on here and found that grounding could be a possible cause, so I started poking around and it looks like somebody removed the ground from the power wire that goes from the cab to the wall (the ground plug at the outlet has been removed and the green wire on the cab end does not attach into the power wire either.) Everything else in the cab appears to the wired properly.

I looked at my DK for a cross reference and it has the 3 prong ground plug and everything is fine with that, no waves, rock solid monitor.

My question is, is there a way for me to safely hook up a ground to see if that fixes the issue? I don't want to electricute myself.
 
i would just reground everything and see what happens.

also change the filter cap and see if that fixes it.
unless you have done a cap kit already.

Peace
Buffett
 
I ran an allegator clip from where the ground connects on the bottom right of the inside of the cab to the ground on the inside of my wall outlet. I'm assuming that's enough to get the thing grounded? Anyway, no dice, slight wave is still there.

I might ad that I have heard sparking on this machine on rare occasions (the screen will sometimes do a single vertical roll when I hear the spark.) This is very rare though. Out of maybe 30 hours of play I've seen it do this a handful of times. It's so rare that I've never been able to verify if the flyback is arching. I'm patient, but not that patient.

I checked the B+ again to make sure it's stable and it's at 108.5 and not moving.

I've read from a couple old posts that this is a difficult problem to pin down. The ones with these subtle jitters and waves seem to be a lot harder to pinpoint than the flag waves, which seem to be tied to the B+. I know that this is not a PCB issue. Testing the two pots on the PCB was the first thing I did way back when, and I've had 4 different PCBs in this cab, all displaying the same symptom.

I'm thinking the following plan of attack,
1) Replace filter cap per buffet's suggestion, if that fails
2) Recap the power supply, if that fails
3) Replace flyback?

Anybody have any better suggestions? The monitor has been recapped recently, but not by me. The picture is beautiful except for the slight wave/jitters.
 
If you have heard sparking, most likely your fly is failing. The sparking is usually from the fly to either the cage or the right hand side of the chassis.
 
If you have heard sparking, most likely your fly is failing. The sparking is usually from the fly to either the cage or the right hand side of the chassis.

Should I just bite the bullet and replace the fly or do you think its worth trying some of the less expensive stuff first? If there's very little chance its the regulator or power supply I don't see the point in wasting time on that.
 
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