[SOLVED] MK3/A1200 : specific monitor triggering horizontal artifacts - works with all others tests

Quote from mahen

Oh, but Guillaume from LesDocs does use the exact same monitor model as me with no issue with the exact same settings. Which doesn't help conclude either. Maybe I can send the screen to him so that he compares them.

mahen

Did you try the CCKLine Pull-Up, the CCKLine Capacitance and PCLK Resistor settings?

You can find those in the Indivision software in the Advanced Options.

This found I somewhere in the forum about glitches and this was Jens' answer:

Jens iComp developer

• Aug 16th 2022

• #23

"As we pointed out in other threads before, these gfx glitches on some A1200s are not Indivision-specific, but computer-specific. Indivision only has a few options to reduce the effects.

If switching on the pull-up on CCK makes a difference, but does not provide a satisfactory solution, then try the CCK capcitance - that's the solution for more computers."

Hereby a screenshot I found from the advanced options.

Before spending money on a new monitor, it might have been an idea to take a picture of any artefacts, so we can find out if the source is in the Amiga, the flicker fixer or something else.

Quote from mahen

you mean, a more precise picture than the videos I provided above ?

No, the video clearly shows that it's a HDMI data transfer issue. If that's the only thing happening, the A1200 board itself is fine.

Quote from mahen

indeed, I have no shield at all. I've been hunting for, but couldn't find any. Yet.

Does the fact it occurs with one monitor but not the other give an indication ?

The input sensitivity of the monitor also influences possible data transfer errors, but if you're already running the A1200 out-of-spec, all bets are off.

Quote from mahen

I would really like to change the titles of the 2 threads I made because, in both cases (although it's still unclear what happens here), your hardware was probably not at fault and it can give bad publicity.

Please message me links to the two threads and the supposed new titles

Quote from mahen

OK, I bought another screen (ASUS) and it works perfectly (apart from VSYNC). No horizontal parasites. I think there is something strange with my LG. Anyway, thanks for confirming I don't have to worry for my Amiga

Good to hear - thanks for the feedback.

Quote from mahen

I have a last question. Is it possible to create a screens compatiblity thread ? My ASUS does not support VSYNC either... I can try a couple of other ones in the following months. Could be useful to other people ? (even though I'm well aware there can be differences between units)

Feel free to share your experiences. However, so far we haven't added such information to the Wiki, as some monitors will work, and other monitors of the same type may not work with VSync because they have a different firmware version.

Also, before you say "Asus doesn't work with VSync either", try Autoresolution with PAL and NTSC first.

On my AGA MK2 (which does not support Vsync) I actually managed to finetune it to get totally smooth scrolling with no vsync. Something I thought was almost impossible. The screen I use for that system is a Phillips 17 inch 5:4 LED screen. And it too doesn't support vsync anyway. So the fact I managed to finetune my AGA MK2 to have totally smooth scrolling without vsync for that specific screen is very convenient for me. It scrolls just as butter smooth as if I would have had vsync enabled. I experimented around the 50Hz region until I hit the 'magic spot' for PAL totally smooth scrolling. And even before I hit that spot I had a profile where I had almost smooth scrolling. A little jerk/frameskip now and then.

So I think it should be possible to do the same with the AGA MK3 for a screen that doesn't support Vsync.

Quote from mahen

Regarding VSync, what I'm attempting to achieve is VSYNC in the native monitor resolution -- it did work with the cheap LCD TV I was lent. But it seems to work with a minority of screens.

Again, there is no single "VSync", but two different approaches that Indivision AGA MK3 offers. Just flipping on the VSync feature will most certainly lead to failure - you need to read the documentation, prepare an output screen mode and check if it's working under WB - and then hope that game modes are sufficiently-similar so it'll continue to work with games as well.

And once again, your chances are even higher with Autoresolution on a HDMI TV set.

Quote from turrican9

On my AGA MK2 (which does not support Vsync) I actually managed to finetune it to get totally smooth scrolling with no vsync. Something I thought was almost impossible.

The MK2 does generate all it's clocks from the Amiga pixel clock, so in theory, the hardware can do it. However, it has no provisions against tearing. What may appear tearing-free on one boot may be different on the next.

Quote from Jens

The MK2 does generate all it's clocks from the Amiga pixel clock, so in theory, the hardware can do it. However, it has no provisions against tearing. What may appear tearing-free on one boot may be different on the next.

Well, so far it's been smooth on every boot. I've seen reports from other MK2 users, with different screens claiming to get smooth results without vsync. Anyway, even if I would get a small tear now and then, it would still be much better than 60Hz+ tearing for PAL software

This wouldn't be "tear now and then", but "static tear point at random positions" - although we'd have to investigate if the static 1s delay for switching input-to-output modes results in a static tear point that ends up in an invisible spot - not excluded without investigation.

However, investigation means that you need to test "switching from any screen mode to PAL", having a logic analyzer or at least a 2-channel scope connected to the Amiga-VSync and the Indivision VSync signal to be able to roughly deduct the tear point. TBH, not worth the effort - if it works for you, it saves you buying a new MK3 unit

Quote from Jens

This wouldn't be "tear now and then", but "static tear point at random positions" - although we'd have to investigate if the static 1s delay for switching input-to-output modes results in a static tear point that ends up in an invisible spot - not excluded without investigation.

However, investigation means that you need to test "switching from any screen mode to PAL", having a logic analyzer or at least a 2-channel scope connected to the Amiga-VSync and the Indivision VSync signal to be able to roughly deduct the tear point. TBH, not worth the effort - if it works for you, it saves you buying a new MK3 unit

Point is also that the particular screen I use for that setup will not work with Vsync from my ECS V3s or VIC II sync from my Turbo Chameleon 64 V2s so I highly doubt it would work with AGA MK3s Vsync. So it's a nice match for my AGA MK2.

Of course I might consider the AGA MK3 aswell, as I have another A1200 that currently has no scandoubler. And I have 2x BenQ BL702As and one BL 912, which all works fine with Vsync.