ColecoVision F-18 Query...

[Sparkoids]

Hi all,

 

Got an F-18 board off Matthew and socketed the board and fitted it easily to a PAL ColecoVision - it's a great product.

 

However when using certain games, both original and via an Atarimax SD cart, some of them no longer work but do when I put the VDU chip back in.

 

Donkey Kong gets to the blue selection screen then goes black screen. I haven't taken an audio tap yet so can't say if it's running in the background but it requires a reset from the console rather than the cart.

 

Space Invaders (Opcode Games) hangs about a minute or so into the game and does the same both on the original cart and SD cart but that will reset via the SD cart.

 

The question is does anyone know how an NTSC or PAL bios differed on the Coleco please? I ask because the F-18 sets the refresh rate to 60Hz which is great but I wonder if the games are reading some sort of timings which are correct on the original TMS but incorrect on the F-18? If I have to burn a BIOS that's fine but I'd like to know if anyone else has had this problem or can offer any help.

 

tia

 

 

James :-}

[Bmack36]

Do the games work if you hit the reset button? Typically you need to replace C3 with a 10uF electrolytic cap instead of the 1uF to slow down the powerup of the system to give the F18a time to boot up.

[Sparkoids]

The games don't work with the reset button on the console pressed. Actually the F-18 boots instantly; there is a slight delay for the monitor to select the VGA port. I have a feeling it's to do with the BIOS and the 60Hz thing but am not sure. I will take the audio tap off on Friday (maxed at work) and see if the game is running. Thanks for the reply :-}

[Bmack36]

The thing to check is to turn the power to the system on and then hit the reset button on the console to see if the game loads better. If the C3 is 1uF then the power on time will be too fast and can cause issues depending on the game. C3 should be a 10uF or larger cap to give the F18a enough time to power up. If you are getting game crashes to black screen shortly after the game select screen you could check out C106 tantalum cap as well.

[+nanochess]

The only difference between American and European Colecovision is a single byte in BIOS telling the frame rate.

 

And no Coleco game checks for it! only recent homebrew games autoadapt music speed using that byte.

[Sparkoids]

Thanks both. I think something else is actually wrong. It runs other games only so far as well then hangs. On DK it stops the console's reset button working. I'm running a diagnostic program on an SD cart at the minute to see what it is but I think it is just disturbing the thing after all these years has done something else. Using leaded solder I have checked and reflowed all chips that looked like they had dry joints and metered the graphics socket to each part of the board and no damage there.

 

C3 is a 1uF 50V cap. Out of interest can I put a 100uF 16v cap in? (I know I can fit it I mean will it work) It's just I have some in a bag here and can't remember how caps work value wise!

 

Cheers again...

[Tursi]

The only difference between American and European Colecovision is a single byte in BIOS telling the frame rate.

 

And no Coleco game checks for it! only recent homebrew games autoadapt music speed using that byte.

 

(OT) Do you have that address handy?

[Tursi]

Thanks both. I think something else is actually wrong. It runs other games only so far as well then hangs. On DK it stops the console's reset button working.

 

... isn't the reset button hardware? Maybe something went wrong with the installation? If the reset doesn't do anything at all, that seems like a good hard point to start troubleshooting from. (I guess you're saying that the reset button works okay with Donkey Kong when the 9928A is installed?)

 

I /think/ that cap should work, there's no voltage up to 16v in there... but best to get a double-check from someone who knows the Coleco board better. Voltage rating must be higher than the highest voltage the cap will experience from the circuit, and farad is the measure of 'capacity', more or less.

[+nanochess]

 

(OT) Do you have that address handy?

0x0069 contains 0x3c for American consoles and 0x32 for European ones.

[Sparkoids]

Thanks Tursi. I'm going to order the proper cap. The console reset does not work on Donkey Kong on black screen crash - I need to meter every connection form the removed VDU.

 

Thanks for the help all :-}

[Sparkoids]

Ok the 10 microfarad 50 volt caps arrived and Donkey Kong nows runs correctly!!

 

I am still seeing crash / hang on the Space Invaders Collection running off the Atarimax SD cart but will need to check with the original cart from home.

 

I am sold on this F-18 - the graphics with scanlines are stunning.

 

Despite some of the games not checking for the PAL/NTSC, 50/60Hz flag in the bios I am not convinced running the PAL 50Hz console at 60Hz via the F-18 isn't responsible for the crash so I'm going to blow some eproms with various bioses and see if it's that.

 

The C3 cap worked OK. A CR network change to delay the reset timing I assume but whats with the tant at C106?

[Bmack36]

Glad to hear it is getting better. According to the tech manuals a bad cap at C106 can cause games to crash (black screen) shortly after the game selection screen.

[Sparkoids]

It is still a bit glitchy unfortunately so I will get onto C106 next - that describes exactly what is happening - the black screen bit. I also have an idea that it may be RAM related. If I leave Donkey Kong on the blue selection screen then it worked sometimes and not others depending on how long before I press start.

There is also a graphics glitch that occurs in different places on different games - like 4 pixels in a line which are a different colour. Here is the pic of Donkey Kong with the blue "line" in his Kong's head. That is on an original cart.

Space Invaders Part 2 still crashes / hangs in the same place everytime leading me to believe a call is being made and the right answer is not getting back OR the 60Hz from the F-18 is referencing the bios re the NTSC/PAL thing. When it crashes the console needs to be power cycled since the reset won't work.

Either way things are moving forward and some games (like Burgertime) are fully playable from the Atarimax SD card. I have even emailed Steve at Atarimax to make sure I have the latest drivers for that device as well.

 

 

I'm going to fix this damn thing if it kills me! Thanks for the help...

[Sparkoids]

OK it is the F-18 or something related to it that is causing the issue. Please ignore my previous post re RAM etc. I just removed the F-18 and soldered the RF modulator back to the board (they are separate on PAL versions). I can now run everything from the SD cart perfectly in terrible RF. Nothing hangs and everything runs correctly. Sooooooo...

 

What is the value of the cap at C106 please? Mine is so old and green in colour (which I assume denotes a tant) I can't read the legend off it?

 

Thanks in advance. I have 5v RAM at the ready if required.... This thing is going to work.... :-}

[Sparkoids]

OK it *has* to be the F-18 I'm afraid - on the games that do play they hang after a certain time but on the RF/AV they are fine :-{

 

Thanks for all the help anyway....

[matthew180]

Usually the F18A is all or nothing, it typically does not partially work or fail. However, I want to get you up and running, so send me a PM or email so we can get something worked out.