PAL SNES Flickering Black And White 60hz

Discussion in 'Modding and Hacking - Consoles and Electronics' started by steocullen91, Jan 27, 2018.

Tags:
  1. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Hi. I have a 1 chip PAL SNES and I've lifted pin 111 and have a switch going to 5V and one going to ground. When I have it set to 50hz it's fine but in 60hz it isn't working. I haven't done the region mod yet and I know I need an RGB cable for colour but I should at least have a steady black and white picture in 60hz right?

    Here's what's happening. Any ideas?

    The screen is showing horizontal black lines and moving down slowly and also you see the same image 3 or 4 times across.

    https://s14.postimg.org/7fbia5nb5/20180128_020507.jpg
     
  2. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    It's the clock crystal - on a PAL 1-CHIP, the master clock is 17.734476MHz and the NTSC one is 21.47747MHz, so when you switch over the video to 60Hz mode it uses the correct dividers for the higher frequency NTSC xtal but it's still being clocked by the slower PAL one. The result is that it generates an entirely off frequency video signal that your TV can't handle. The frame rate is close to correct, but the line rate which should be 15.734kHz in NTSC mode is actually coming out at about 13kHz, which is well outside the range your TV will be able to handle.

    Basically, you need to add another switch to control the xtal in use - I think bad_ad has some little PCBs that have the xtals on them, so it might be worth checking his sales thread.
     
  3. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Thanks for the reply. That makes sense then. I might be better to get the switches that are doubled so I can have just one switch to switch the framerate and xtal together and then just have the other switch change the region.

    I'll have to check it out as I'd imagine they're hard to find the specific type of crystal. Is there any chance the crappy FC twin I have might even have the right crystal since the snes part of it won't even read games? It's basically just a 60hz nes with snes controllers and a bad colour palette.
     
  4. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    I'm not familiar with the hardware on that console, but if it's designed to run at 60Hz it's quite possible it has the right xtal in it. See if there is anything marked "21.477" or similar.
     
  5. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    I will check it in the morning. It's 4am here so I need some sleep. The snes kept me up all night and I wasn't even playing it
     
  6. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    You legend. I'm after being sitting here like a moron googling rjh21 4772a then just realised 21 477 is what you said. Nice! But now I'm gonna need another switch. I have to get a double lane switch so I can put the oscillator on the same switch as the 50/60 hz and then use this one here for the region mod. Is there a reason why people put Europe and 60hz switches at the same time? Like I mean is there a benefit from Europe and 60hz in some games compared to just region mod 60hz? I'm going to need 2 switches either way but just wondering.
     
  7. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    If you are switching over the CIC and the 50/60Hz mode then using two switches allows you to select the PAL CIC but with 60Hz video, which makes some games run better (and messes up some others...)

    In the case of the 1CHIP video mode stuff there is no point in using separate switches because you always have to switch the 50/60Hz line and the xtal together - if you put them on separate switches then you would end up with 4 possible sets of switch settings, but only 2 of the would make any sense.
     
  8. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Yeah I know what you mean. I know I need the double lane switches otherwise I'll just short circuit everything. I'm literally using a light switch just to test the crystals and they both work in circuit. So I'm better off using the region mod on it's own switch basically and just getting the double lane one to hook the refresh rate and crystals to the same one right?
     
  9. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    Yeah - you've already seen the effect of switching the chip to 60Hz with the PAL xtal in circuit and switching to 50Hz with the NTSC crystal connected produces a similarly broken video output, so the only thing that makes sense is to switch them together.
     
  10. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Thanks I'll pick up a switch for this and just to be sure should I use a 2.2k resistor also? Sorry for all the questions but there's a lot less info about this 1 chip model. For the region switch is it still pin 4 to a switch between gnd and 5v for selection or is it different again on the 1 chip?

    If it had been the 2 ppu model everything would've worked and I could have followed a guide but I'm asking lots of questions instead and I'm lost lol.
     
  11. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    You don't need to add a resistor, although it's harmless (and reduces the risk of blowing the fuse if you short something out).

    Strictly, pin 4 on the CIC doesn't change the region - it just disables the chip completely. The practical implication of this is that when the chip is disabled certain games (notably including SA1 based games like Super Mario RPG) won't work at all.
     
  12. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    The way I have it at the moment my super Mario all stars + world cart won't boot if I start it set to 60hz even with pin 4 lifted. Should I disconnect pin 9 of the RGB chip also as I've seen that you should to fix composite. Though I'll be using RGB anyway.

    What should I connect pin 4 to for fixing the region then. Is it 5v CIC enabled and GND disabled?
     
  13. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    OK, there are two different things here - one is that certain games have code in them to check if the video region of the console matches with the cart is expecting and stops the game if not. This sounds like what you're running into - in that case, you can start up the game in the mode the cart is expecting and then switch it over to the other one after the video mode check.

    The problem with the SA1 based carts is a little more subtle - the SA1 has the CIC function built into the chip and has a function that will disable access to the cart ROM unless it detects the CIC in the console.

    And yes, 5V is CIC enabled and 0V is disabled.
     
  14. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Perfect thanks. I'll connect it to a second switch so I can do that manually. The Mario game also glitches at 60hz but again I seen that can happen with some games. I have an old flash cart that could fit maybe 7 or 8 games on it so might just put the ntsc version of Mario on that for now. I could buy the ntsc version but I've to mod the case then to fix them carts.
     
  15. Bad_Ad84

    Bad_Ad84 The Tick

    Joined:
    May 26, 2011
    Messages:
    8,618
    Likes Received:
    1,387
    The pcb solution trimesh mentioned is much better. But will take a little more skill to install.
     
  16. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    I have it done anyway but I forgot to lift pin 9 and I'm just going to leave it since I'll use RGB. If I get my hands on another snes I'll try out the pcb method on it definitely as it looks cool.

    Sometimes when I flick a switch if the game is running it just goes black for some reason and I have to press reset. Shouldn't matter as I'm not going to keep flicking mid game but just for them games that give the region message.
     
  17. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Ok so I decided to lift pin 9 of the srgb chip to fix composite. I tried to wire it up to the same switch as pin 111 and heard that doesn't work because they're the opposite. Like it's pin 111 to 5v for 50hz and to GND for 60hz but then pin 9 is 5v for NTSC and GND for PAL. I already have a switch for region and then a separate double pole switch that does the crystal and refresh rate together but now I'm going to need yet another switch by the looks of it if anyone has any ideas.

    So basically in 60hz my CRT had the wrong colours with composite then lifting pin 9 and connecting it to the switch with pin 111 gave the same result. Disconnecting the wire from the switch and just leaving it floating fixes the colour and it works in colour in both 50 and 60hz but then I decided to test my LCD 4K TV just to see what would happen and with pin9 not connected to anything 50hz is the wrong colour on it but 60hz is in the right colours.

    I'll be using my CRT and getting a good RGB cable so should I just leave it the way it is or am I likely to run into issues on another CRT? As I said I'll be using RGB but still just wanted to try make everything work. RF is also black and white with the pin lifted and not connected but I assume that means it's in NTSC and nobody uses RF anymore anyway lol.

    What should I do with pin 9 so. Just leave it floating or get yet another switch?

    The switchless mod you guys were talking about is looking better and better but I'm afraid I'll end up breaking the SNES trying to desolder everything like break a leg off a chip for example. I've already had to bridge the fuse with some wire because I shorted the SNES accidentally by not testing it with a multimeter first.
     
  18. TriMesh

    TriMesh Site Supporter 2013-2017

    Joined:
    Jul 3, 2008
    Messages:
    2,372
    Likes Received:
    785
    Yeah, the PAL/NTSC switch line on the encoder is in the opposite sense from the one on the main chip so connecting them together will not be very helpful.

    You might be able to get away with just leaving the encoder in PAL mode - that way it will generate PAL and PAL60, which is a format that's widely accepted by TVs.
     
  19. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Might give that a try so and see if I can get away with it. I'll just solder it to the other end of the 2.2k resistor I have between the switches. That way it should get 5v for PAL.
     
  20. steocullen91

    steocullen91 Rising Member

    Joined:
    Jan 27, 2018
    Messages:
    62
    Likes Received:
    16
    Ok so that wasn't working for me so I just added a third switch. My CRT does have colour in 60hz with the cable grounded but you can see if you switch it in game that NTSC is a lot more vibrant like much brighter and when I switch to pal they change to slightly less bright which is what it always did look like. Very surprisingly my CRT isn't actually handling that set to GND at 60hz which it PAL60? So basically it's handling PAL50, NTSC50 and NTSC60 but not PAL60?

    It's either that or the signal must be reversing depending on the hz it's set to. Either way I just added a toggle switch that goes to GND and just plain off no connection as that seems to work.
     

Share This Page