Apart from the set of jumpers and colour subcariers clocks and RF modules what's the difference? are there other clocks running faster or slower, maybe using different multipliers. http://www.youtube.com/watch?v=ZvyUFWPstwM Since I got a new main TV ( Sony KDL55x8505b ). My PAL megadrive 1's the scroll test seem to tear and glitch every few seconds. One is 50/60 modded and the other is stock. This TV's built scaler and scart socket seems to handle everything else including 240p patterns in the test suit pretty darn good. Stupid thing is it does it at 50 and 60hz. I do not have a JP or US megadrive console to make comparisons. My US SNES runs perfect. which is good with no scrolling glitches. My pal snes is glitchy in the same respect too but that's for another thread.
They use identical hardware, but different master oscillators (which are multiples of the subcarrier). The "50/60 Hz" jumper selects which set of dividers to use to generate the subsequent clock signals. The masterixel clock ratios are identical for both modes so it's assumed there is only 1% timing error which is negligible when using RGB. Does your TV glitch with the stock console?
Yep stock pal console tears. my moded one tears on both 50hz and 60hz So it's probably not close enough to 50hz for my TV's analogue circuits liking. My PAL snes is 50/60 HZ modded, it's fine at 50hz and tears and has issues with the odd frame a little at 60hz. My US SNES is perfect at 60HZ. It's seems on some occasions the slightly off refresh rate, it's not insignificant enough for my new TV. It did suck having to give up my old pioneer kuro LX-5090 TV ( due to major pixel misfires as a result of a bodged repair job by so called professionals). That TV just didn't seems to care about the slightly off PAL / NTSC refresh rates at all. a few months ago I needed the space so I moved my old RGB scart CRT into the Shed. I found out what the master clock values are here > http://www.zipplet.co.uk/index.php/content/electronics_mdpal60 . looks like I'll be out of luck unless I can find a dud Genesis/Jap megadrive or order 20 from china.
It's your display. Not the consoles. For absolute maximum quality on 80s and 90s vintage consoles CRT is the way to go. Trust me. The closest you can get to that is a good computer with dscaler plus a capture card or a expensive Japanese scaler like the XRGB thing. I particularly use a BT878 card (no drivers installed) and dscaler4. Performance is very decent. No tearing, no artifacts and it can make screenshots.
I know my display isn't handling the slightly off spec 60HZ. I just ordered a Jap MD. CRT's are nice when they are set-up and freshly de-gaused, and had the geometry tweaked, FYI I have a sony KV29X5 in storage. If I had enough room it would be out. However apart from the tearing from the slightly off spec signal, the internal de-interlacer on my new Sony LCD handles 240p nigh on perfect which is a rather nice surprise. The US SNES is utterly bang on the 240p test suit( So is the mega drive apart from tearing on the scroll test) . I get it the xrgb would be better but how much seeing as it's already handling 240p properly?
Like I said these consoles were developed for CRT and never considered a 100% to the spec output. Something like 95-98% which is perfectly acceptable by CRT standards. So it might still tear the image up with the original NTSC oscillator ... I would like to hear your results with a Japanese MD console.
All 16-bit consoles are slightly off-spec, including the MD you just ordered. I'd be surprised if it made a difference, but let us know. More likely the TV is tripped up by something about the MD's frame timing or sync.
Yea, could be, My Pal Sega Saturns a bit iffy too at 60HZ. I don't understand why the 50hz signal on my Megadrive's are causing an issue. I would of though the pal one would of been tuned to provide a more stable PAL signal. I also checked around a few other forums. I'm sure one guy posted that the JP megadrive gave no issues at 50hz or 60hz while the pal one did. On the video the guy has his Megadrive piped through an Extron 203i which measured the pal MD's 60hz signals Vertical refresh rate at 59.2HZ and the NTSC model at 59.9HZ. That is probably enough to cause an issue with a modern TV. I suspect while PAL machines had the master clock tweaked to get the master clock/12 divider output closer to 4.43xxxx MHZ , maybe it actually put both signals vertical refresh slightly out of wack, and unnoticeable until the even of digital displays and having to reconvert the analogue signal to digital. We'll soon see as my MD is on the way over from Japan by EMS so i should have it next week. I do remember some CRT's in the early days of messing with my media PC, I was able to get away with tweaking the signal down to 48hz perfect for watching 24fps movies. I do think the ultimate fix might be to replace the master clock with an NTSC one or a slower more readily available crystal multiplied to 53.6931Mhz, and feed the video encoder with it's own 3.58Mhz or 4.43Mhz to get the console behaving more on spec. Assuming my TV loves the JP Mega Drive.
The only differences on PAL vs NTSC Mega Drive units of same revision (parts wise) are the master clock oscillator and a few analog parts around the CXA1145 chip (due to color carrier frequency differences).
My Suspicions are confirmed. The Jap Megadrive is solid as a rock scroll test wise, Also an un-expected other side affect the picture is perfectly centred via the same RGB cable unlike my pal 60 HZ Megadrive. The PAL megadrive at 60HZ the picture is shifted right a fair bit with maybe 3 pixels off the analogue circuits range sample range. I I've yet to test it at 50Hz but I will later if it gives similar results. I've only opened up the case and removed the cartrige lock so far and tested. So it is perhaps worth it for someone with issues like mine or a problem with the picture shifting to the right to swap the clock out for the NTSC console clock and feed a separate clock the to CXA1145 if they are not using RGB. The picture is as near perfect a RGB picture stock MD1 can output and the TV handles it superbly so good it's making me thing I really don't need a xrgb mini until I get a smaller gaming monitor.
Hello everyone. I'm having the same problem with my 60hz modded Mega Drive. Since the master oscillators are different the picture signal even with RGB cables are slightly off. On both my TVs the picture gets off-center and on one TV-set it keeps flickering as well. I've done the 50/60hz mod and would like to have correct picture signals in both frequencies. I've ordered a XRGB-mini which should arrive shortly, but according to the XRGB-wiki the problem will remain. I've tried and read up on the problem and found some really complicated solutions with programmable circuits with can switch between the two frequencies. That seems like A LOT of work that requires some special equipment and a lot of reading up. However, most posts state that the reason for all these complicated solutions is mainly the lack of suppliers for the oscillator crystals with the correct frequencies. I have a PAL Mega drive with the PAL crystal of 53.203425 MHz. I've found a supplier of the NTSC crystals on aliexpress (53.693175 MHz). I don't want to just switch out the PAL crystal with the NTSC one because that would give me the same problem as I'm having right now, but when I'm in 50hz mode. So. Can I desolder the PAL crystal, put it on a board with my NTSC crystal. Just put a switch between the 5V supply on the crystals and have both Outputs go back the the MD? Then I would be able to have a DPDT switch for my region mod that also switches between my two crystals? Seems pretty simple and it worries me that I haven't read about this solution anywhere. Am I missing something?
