nms 8245 joystick port failure ?

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Door GreyFoxNL

Rookie (23)

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20-11-2018, 23:16

Hello everyone,
today i got a very nice nms 8245 i bought on marktplaats.
The only downside of the machine is that game port 1 is always in the "up" position.
In basic everything works fine with the keyboard but when i start a game, the vehicle or character is always moving up. Even when there is no joystick connected en no one is touching the keys.
In basic i typed:
10 print stick(0);stick(1);stick(2);stick(3):goto 10
Where this should give: 0 0 0
This is what i see: 0 1 0
When i connect a joystick and move it down the 1 in the middle becomes a zero, suggesting that joystick port one is always in the "up" position.

Has anyone had this problem before or does anyone have idea on how to fix this issue ?
Thanks in advance !!!

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Van GreyFoxNL

Rookie (23)

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21-11-2018, 01:02

10 print stick(0);stick(1);stick(2);stick(3):goto 10 is one stick to many obviously Big smile

10 print stick(0);stick(1);stick(2):goto 10 is what i actually typed.

Van meits

Scribe (6571)

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21-11-2018, 01:40

Do you have a joystick inserted? If so, check continuity between pin 1 right top hole in the joystick connector) and 8 (down, second from the left hole). If you hear a beep while you're not touching the joystick, there's your problem.
If it's the computer, check the same pins (mirrored horizontally). If they connect, open the computer and check if it has been resoldered or so dirty that it might conduct.

To the hardware guru's: How come I can't check this on fire buttons A and B?

Van Jipe

Paragon (1625)

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21-11-2018, 11:08

joystick port is directly connected to S3527 chip

Van GreyFoxNL

Rookie (23)

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21-11-2018, 11:45

The problem occurs both with or without the joystick connected.
All looks fine with the computer, nothing tampered with.
I've been in contact with the fella that sold me the computer.
He tested it with various games on a megaflashrom and it worked just fine.
I used original roms and disks, and encountered the problem.
So seems that something happened during transport because i cant imagine that the problem wouldnt occur when using MFR but would occur with original software.
I assume the s3527 chip located on the mainbord?

Van Jipe

Paragon (1625)

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21-11-2018, 12:30

try desold LF19 self ( Forward ) and check with a game

Van gdx

Enlighted (6427)

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21-11-2018, 12:43

Try to change the LF19. If you only desolder it, the signal will always remain to zero and it will not change anything.

Van Jipe

Paragon (1625)

afbeelding van Jipe

21-11-2018, 14:05

is just for find the defect component

Van AxelStone

Prophet (3199)

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22-11-2018, 14:14

Similar problem here with VG8235, in my case if no joystick is plugged it works like trigger1 would be pushed all time. I have to let one pad connected all time to avoid this effect, and only works with MD pads, if I connect a native MSX joy / pad it doesn't avoid the effect.

Quite strange!

Van sd_snatcher

Prophet (3675)

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22-11-2018, 20:51

AxelStone and GreyFoxNL

Do you have a multimeter? Measure if between the pin-5 and the other input pins of the joystick port there's 22K Ohms. Specially the defective pins.

Report the results here and I'll think of something.

Test if a Megadrive joypad works like on AvelStone's machine. You'll need a JoyMega adapter for that.

Van Omega

Master (233)

afbeelding van Omega

24-11-2018, 19:12

Aaand it's fixed Smile

It turned out it wasn't LF19:

So unfortunately it required a MSX-Engine swap *_*

bad engine begone:

replacement engine (from donor board) installed

GreyFoxNL happy. :)

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