TC64 V2 Scanlines and ghosting on LCD

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Don't Panic. Please wash hands.
  • So a few questions.


    So I use BenQ BL 702A and BL 912 LED screens for my TC64 V2 setups. I use them in cartridge mode. I have resolution set to 800x600, 50Hz and synced to VIC II. They work fine with smooth scrolling. So question about the scanline settings. There are 4 options. No scanlines, 25%, 50% or 75% scanlines. So what does the percentage numbers mean? I find 75% tend to give more washed out colours. 50% gives okay colours and 25% gives the most vibrant colours. However, 25% seems to give the most intense scanline effect then 50% and then 75% seems to give less intense scanlines. Why does 75% give washed out colours but going more intense scanlines intensity gives more vibrant colours?


    Also I read somewhere that using LCD screens on the TC64/TC64 V2 gives some ghosting which will not happen if a CRT is used on the VGA output. I have quite a bit of ghosting on the above mentioned screens. And yes, I have tried out various high quality VGA cables. Same results no matter what VGA cable I use. So is there any explanation for this ghosting and can anything be done in a future firmware?

  • As for the scanlines... the 4 options really just set the intensity of the scanlines, the colors are not affected. The problem at this point is that if you do not operate the monitor/display at its native resolution - the monitor will scale the image, including the scanlines, and that creates various artefacts and the colors may change as a result too. The only way to fix this 100% is to either disable scaling on the display, or to use a display with the same native resolution.


    The ghosting... i think that is mostly an issue of proper signal termination (at the monitor), and we cant really fix it. Jens can perhaps tell more

  • The ghosting problem is really something that varies extremely with the used screen(s) and screen refresh rate. Chameleon is designed "by the book" for 75 Ohms-terminated RGB lines, but it appears like especially Samsung monitors don't like that bog-standard-signal at all. The monitor cable won't help much, but reducing the output resolution/pixel clock will, as the AD converters in the monitor(s) appear to vary a lot. Looking at standard AD chips used in LCD monitors, I see that they are all AD-coupled, so there's quite some software involved on the monitor side. This software part can obviously be fooled if we violate CE recommendations and add high-frequency content on the RGB lines. That said, I don't recommend removing the filter caps and replacing the driver transistors for faster types, as it may solve the ghosting problem, but result in EMI problems.

  • The ghosting problem is really something that varies extremely with the used screen(s) and screen refresh rate. Chameleon is designed "by the book" for 75 Ohms-terminated RGB lines, but it appears like especially Samsung monitors don't like that bog-standard-signal at all. The monitor cable won't help much, but reducing the output resolution/pixel clock will, as the AD converters in the monitor(s) appear to vary a lot. Looking at standard AD chips used in LCD monitors, I see that they are all AD-coupled, so there's quite some software involved on the monitor side. This software part can obviously be fooled if we violate CE recommendations and add high-frequency content on the RGB lines. That said, I don't recommend removing the filter caps and replacing the driver transistors for faster types, as it may solve the ghosting problem, but result in EMI problems.

    I've tried all kinds of LCD monitors. They all show quite bad ghosting/smearing to the right of the objects. Just like with the Indivision ECS V2. There is no difference. They all show the same ghosting/smearing. Might I ask what kind of monitors you have tested that shows little to no ghosting?


    Also, the only review of the TC64 V2 is from C64 Customs. He aswell spoke of bad image quality. Facebook group says the same. Yet there is little to no ghosting with the Indivision ECS V1 with the same monitors and cables. I also hear reports of the TC64 V1 has much better picture quality than TC64 V2. Here the other day a guy from the facebook group had just bought himself a TC64 V2 and he was shocked and dissapointed by how bad the picture quality was VS his TC64 V1. He also tried all kinds of monitors.


    You say pixelclock. No matter what resolution one tried from the TC64 V2 the ghosting is still the same.


    You may have done it 'by the book' as you say, but something is wrong when your older products have superior picture quality. You also have a thread for ECS V2 that is full of people reporting the ghosting issues. As said, the TC64 V2 has the exact same problem the ECS V2 has.


    Now if there is a solution that involves changing surface mount components on the TC64 V2 and ECS V2 I would like to know so I can fix them myself. If 90% of monitors shows the ghosting problem on your TC64 V2 and ECS V2 but not on TC64 V1 and ECS V1 then the problem is not the monitors, but the source.


    Edit: A good example is like with my ECS V1, if I have it set to 62Hz mode it will switch my BenQ BL 702A and BL912 to 1024x600 with little to no ghosting. I have to use a really low quality VGA cable to re-produce the same ghosting the ECS V2 and TC64 V2 has. With the ECS V1 I can look at the pixel clocks in the ECS V1 tool. Now, if I create a profile with the ECS V2 where I re-create the pixelclocks from ECS V1 and make the BenQ monitors switch to the same resolution it does not matter. The ghosting is still horrible. It doesn't matter what pixelclock or what monitor I try. Tried a bunch of other LCD monitors aswell. CRTs are out of the question.

  • My personal favourites at the time were Dell monitors with 1280x1024 pixels.


    Jens

    So I was watching Custom64s (youtube site now named 'Daniel Renner') review of TC64V2 docking station closely. I couldn't see any ghosting/smearing in his recordings when he was using the VGA output of the TC64V2. It would be especially noticeable on the minimig kickstart 3.1 screen. Yet I couldn't see any smearing on the right side of the objects in his recordings.


    The difference between his setup and mine is that he was using a VGA to HDMI converter. So I have orderered a couple of the exact same VGA to HDMI converters he is using in that video. My hope is that these VGA to HDMI converters handles the VGA signal from TC64V2 better than most LCD screens. So maybe when I try VGA to HDMI to DVI on my BenQ BL912 this will remove my ghosting/smearing. I also have HDMI to VGA converters laying around. So I could even go VGA to HDMI to VGA.


    If this works it will probably work for the ECS V2 aswell.


    Will keep you posted about this. It will take at least 10 days to get the converter.

  • What converter is he using? I was skipping through the video but couldn't even catch a glimpse of it.

    There is a small glimps of it in the video. Where he shows two different types of VGA to HDMI converters he has tried. The one he says works well with scrolling and converting the signals are the 'VGA2HDMI'. If you search on ebay for VGA2HDMI or VGATOHDMI you will find the same one he is using. At least they look the same. The innards may be different. Who knows. It's a little square box in either white of black versions. It says on the outer top shell 'VGA2HDMI' or another type has 'VGATOHDMI' written on it.


    I can probably not post links in this forum anyway.


    I don't have high hopes but it's worth a try because in his recordings I could not see ghosting/smearing. Most people agree that the image quality from the TC64 V2 are bad. Same with the ECS V2. I suspect bad/cheap components in the output circuitry. Hence there will not be any support from this forum. There are way too many reports of these problems for it to be isolated to specific monitors or setups. I don't believe so many monitors are to blame. It's the source (TC64 V2/ECS V2) which causes the ghosting/smearing. Oh, and does not matter how high quality of a VGA cable one uses. The ghosting is like if I try a low quality VGA cable with no ferrite cores on the ECS V1. That is how it looks on TC64 V2/ECS V2 no matter how high quality VGA cables I use. Or other people have tried.


    I've tried probably 6 or 7 different monitors and TVs with VGA. Exact same ghosting. If it was certain monitors that was at fault I would at least see variations between how bad the ghosting/smearing was between different screens. Also, take a look in the ECS V2 ghosting thread. So many people with all kinds of setups and monitors. Even Dell monitors which Jens mention further up. Does not matter. Same problem. Take a look in the facebook group for TC64 V2. Same problem.


    And again, same monitors and cables show little to no ghosting on ECS V1, AGA MK2 (when using VGA).


    So the little hope I have is that converting the signal from VGA to HDMI with that converter may get rid of the ghosting. Based on my observations from the video mentioned earlier. With that said, the author of the video said in one of his videos that the TC64 V2 has a bad picture quality.

  • So of course I haven't recieved my VGA to HDMI converters yet. But I've been looking at another video from custom64 (Now named just Daniel Renner on youtube). Video is called 'C64 related - Turbo Chameleon V2 - new Minimig Amiga core, sneak prev new C64 core'.


    In this video we see some fullscreen recordings from the minimig core. He is of course using his VGA2HDMI converter talked about earlier in this thread. And with fullscreen in this video we can clearly see the quite nasty ghosting/smearing when he shows the kickstart 3.1 screen from the minimig core. You can clearly see the smearing on the right side of the Amiga logo and also on the right of the moving floppy disk. So VGA to HDMI converter will not help. Will look even worse in real life.


    TC64V2 and ECS V2 output quality is just bad.


    If Jens would come forward and tell us how we could rebuild the VGA circuitry for the TC64 V2 and ECS V2 to get the same quality picture ECS V1, TC64 V1, AGA MK1 and AGA MK2 has that would be nice.