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First of all I double checked the 720x576@60Hz with vic II sync ON for the BL912. And yes, it does indeed switch to 832x624@50Hz.
Then I tested my two BL702As. They do exactly the same, as expected. They also do the exact same thing my BL912 does with regards to the 720x576@50Hz and VIC II sync ON setting.
I highly doubt that all 3 monitors are bad.
This kind of testing does not really help though. As said before, there is no right or wrong way to do a 720x576 mode, as there is no standard for it. What would help is when you use the timing from the mentioned modeline(s) and tweak it until you get a stable picture in a 720x576 mode at 50.2Hz
Do you need exactly 50.2 or can it be a little bit over or under? Like 5.267 or whatever?
The whole trick is to calculate if the "one line difference" is really sufficient to bring the vertical duration across the 0-mark. Note that the number of lines should only alter by one, and ideally, the "short" screen is really shorter than the host computer's screen, while "one line more" makes it longer - then you have the highest chance of success.
This is the closest I got. I tested 10 + coldboots and it held 720x576@50Hz. A notch lower and it would switch to 1080i the next coldboot. Below 50.2 was a no go. So 50.2384 seems solid on every coldboot
now you gotta try what happens if you remove or add another line 
now you gotta try what happens if you remove or add another line
What do you mean by adding/removing a line? Where do i do that?
modify back porch and/or sync in the vertical timing, each step there is one line
Oh, any specific value you want me to aim for? You want me closer to 50.2?
We can't exactly copy the results from an Amiga to the Chameleon, as the host computer's frequencies are not the same. We can merely show that there's a small window where the monitor accepts the output as "what you want", but there's no guarantee that we'll hit that same window with the Chameleon, as both the base frequency of the FPGA and the vertical frequency of the host computer are different.
Two more. The 50.1575 survived for 10 + coldboots. The 50.3196 survived for 9 coldboots. Then after the 10th coldboot it switched to 640x480 for the ACA 500 screen. But then switched back to 720x576@50Hz as I entered workbench. I'm not expecting these to last for 100 + coldboots. But 10 in a row is pretty good. I don't want or have the time to do 100 coldboots. LOL. Will wear out the power button. LOL
So it was impossible to adjust the timings in the profile for the TC64 V1/V2 720x576 50Hz to match what I found worked quite well in my last post here using the ECS V2?
Didnt Jens answer that above?
Another problem with using someones tweaked values (instead of values calculated the standard way) is that it will almost certainly break it on someone elses monitor then, which is why i am very reluctant with doing this
The BenQ BL 702A and BL912 are quite popular for both the TC64/TC64 V2 and also the Indivision scandoublers. Due to it syncing perfectly to 50Hz PAL and also 60Hz NTSC. So quite a few people have these monitors.
However, I understand your issue. If the current profile works well with many other monitors then that could cause problems if you changed the timings to something similar I showed here by using the ECS V2.
You would need a tweaked version for us BL 702A/BL 912 owners then. Maybe offer a tweaked version via mail? People send a mail and you provide a link?
No, extra versions for specific monitors are a support nightmare. And considering the amount of people reporting problems with the current parameters equals 1 that isnt quite worth it, sorry.
That's fine. Very understandable. 768x576 50Hz VICII sync on works well with these screens. So not the end of the world. Also, 720x576 60Hz and VICII sync off will fill the screen and not forget the setting.
so testing various lcd monitors and one of my tv's I found that many of the 'prefered' resolutions like 800x600 50Hz, 720x576 50Hz and 768x576 50Hz will switch many of the tested monitors to 640x480 and cause the bottom of the picture to not show. Robinson5 fixed this issue in the minimig core by allowing us to invert the sync. Would this be possible for the c64 core? Giving an option in the menu to invert the sync?
At this point it'd be most interesting to quantify "many". Which monitors are this and what exactly is the problem with them?
As you know the BenQ BL702A and BL912 struggle with 720x576 50Hz. They often switches to 640x480. Same with 800x600 50Hz. Always switches these monitors to 640x480 and cutting the lower part of the image. 768x576 works fine but will not stretch the picture to the edges horizontally and show black bars on the sides. Several other monitors, like a Phillips 17 inch LED, a couple of modern ASUS 24 inch LED screens, a Sony LED TV some VGA to HDMI converters I have. they all struggle at certain 'ideal' resolutions. What I mean by 'ideal' resolutions for the TC64 is 720x576 50Hz, 768x576 50Hz and 800x600 50Hz. These resolutions are key to give a nice picture with the TC64/TC64 V2 due to the lower pixelclock and at the same time correct aspect ratio. Higher resolutions or higher than 50Hz gives a really poor picture. 640x480 50Hz is nice and sharp but will not give the correct aspect ratio and not show the whole picture for games/demos that uses the whole overscan.
I suspect giving the option to invert the sync polarity would fix some of these issues and make the TC64/TC64V2 more flexible with regards to monitors and finding nice resolutions? Would it be hard to implement this as a menu option under the VGA settings?
The last reply was more than 365 days ago, this thread is most likely obsolete. It is recommended to create a new thread instead.
