Sanyo 20-EZV has jitters

[MaximRecoil]

I posted about this on KLOV, but haven't found a solution yet (this is the thread).

I'll paste a couple of my posts here:

I just finished a cap kit (using Bob Roberts' "Plus Kit with 9 more chassis caps"), and there was no change. The jitteriness is slight, but constant and at a fairly fast frequency. It does not go away as the monitor warms up. The monitor's picture looks perfect in terms of color, brightness, etc., aside from the jitters.

I asked Bob Roberts about it and he said:

No magic answer for jitters... there are many things that could be
responsible from the input to the output to the CRT.

There has to be some causes of jitters that are more common than others, and I'm guessing that there are some areas that can be eliminated because they couldn't possibly cause jitters.

Any idea where I should start?

And:

So I finally got around to working on this monitor again. I replaced the filter capacitor (C606) and I replaced all 5 pots on the monitor control board with new ones (VR351 through VR355), and there was no change.

Remember, this is a Super Punch-Out boardset and it has no VR1 & VR2, plus the jitters are definitely a monitor issue, because the machine's original monitors don't jitter when hooked to the same boardset.

So the two original Sanyos in the machine don't jitter, but both of the Sanyos that I want to replace the originals with (because they have perfect tubes, i.e. no screen burn and they have bright, accurate colors), jitter. It is weird that they both have the same jitter issue, because they have completely different histories; i.e., they didn't come from the same machine, nor even the same part of the country. I've only tested them with them sitting on the floor next to the SPO machine ... would it make any difference if they were actually installed in the machine (maybe something to do with ground)? I'm thinking: probably not.

I took a video of it but unfortunately, the jitteriness doesn't show up on it. The video is either not high enough quality to capture it or doesn't have a fast enough frame rate (there isn't a lot of movement in the jitter motion, but it is quite rapid).

Does anyone have any other ideas? Could the flyback transformer be causing this?

[MaximRecoil]

I've only tested them with them sitting on the floor next to the SPO machine ... would it make any difference if they were actually installed in the machine (maybe something to do with ground)? I'm thinking: probably not.

As it turns out, it does make a difference if they are actually installed in the machine, but not because of anything to do with ground. When viewed through the cabinet's tinted plexi bezel, the jitters become imperceptible. Remove the plexi and look directly at the monitors, and you can see the jitters again. It is weird. I'm sure there is a scientific explanation for it, but I don't know what it would be.

So before made that little discovery, I had already swapped the perfect tubes over to the original chassis and frames. When I finished doing that and tested them on the floor beside the machine, they still jittered. I was thinking, "How can this be? Are the tubes themselves causing the jitters?" But at least the weak/dark reds problem with the upper monitor was solved, and the raster looked great on both of them due to the perfect tubes, so I said, "Screw it", and installed them in the machine anyway. And as I said, once the tinted plexi was in place, the jitters were no longer noticeable. As a bonus, I still have the matching 20-Z2AW monitors that originally came with the machine installed in there (albeit with replacement tubes), instead of a random pair of 20-EZVs, so it was worth it.

[Paradroid]

Fascinating reading.

I've tested a great number of SCART televisions with MAME (running at native resolutions using an RGB connection) and I've always wondered what causes the subtle jitter present in some TVs. It's certainly possible to have an image with zero jitter (some of the the upmarket models I've tried are incredibly stable) but the last time I saw a collection of real arcade games (pretty rare in my part of the the world these days) I was shocked to see that every single screen had far more noticeable jitter than any of my SCART TVs.

It seems like you've found a solution you can live with. After all the work you've done on those chassis I would have loved for you to find an electronic solution so we could know exactly what causes your image jitter.

Oh, did you say the jitter was in the vertical aspect? Mostly I see only horizontal jitter in my screens...

[MaximRecoil]

It seems like you've found a solution you can live with. After all the work you've done on those chassis I would have loved for you to find an electronic solution so we could know exactly what causes your image jitter.

Yes, it would be nice to get a perfectly stable raster electronically, but I'm not even sure that's possible with a Nintendo Sanyo monitor. As I mentioned, I came across a post here where the author said that "some jitter is normal". I was skeptical because my SPO machine's original monitors seemed perfectly stable, but they really weren't; they only appeared to be when viewed from behind the tinted plexi bezel.

I do have three machines that all have fairly new Happ Vision Pro CRT monitors in them, and those all have perfectly stable rasters, even when viewed directly. I love the picture quality of Happ Vision Pros; very sharp and perfectly stable. It is such a shame that they are no longer manufactured.

When Vision Pros were still available I considered buying a couple for my SPO machine, but it would have required too many modifications (due to Nintendo games outputting inverted colors and using an external audio amplifier that is built into Nintendo Sanyo monitors); and because SPO is my "grail", I wanted to keep it as original/OEM as possible. For the same reason, I haven't bought a new/modern switching power supply for it, but rather, I recapped its original PP-1000A power supply.

Oh, did you say the jitter was in the vertical aspect? Mostly I see only horizontal jitter in my screens...

Yes, and just so that we're on the same page, jitter on the vertical axis means up and down jitter motion when viewing a normal horizontally mounted monitor (like in Punch-Out / Super Punch-Out), but it would mean side-to-side if viewing a vertically mounted monitor (like in Donkey Kong).

[MonMotha]

Do you still get this "jitter" on progressive video signals or only on interlaced?  Many older (and/or cheaper) arcade monitors just weren't designed for interlaced signals and don't handle them properly.

[MaximRecoil]

Do you still get this "jitter" on progressive video signals or only on interlaced?  Many older (and/or cheaper) arcade monitors just weren't designed for interlaced signals and don't handle them properly.

This is an actual Super Punch-Out PCB (I also have a Punch-Out PCB, same results), not MAME; it is a progressive video signal.