Gorf Joystick Down not working

[rchadd]

there seems to be issue with one of my Gorf Game boards - moving the joystick down is not working

even in test mode it looks like the joy down switch is not working

when i try a different game board it works ok - indicating it is an issue with the game board itself.

are there components on the game board that handle I/O from the joystick? any components specific to handling joystick down that i should consider as potentially being faulty?

would appreciate  any suggestions on this

[rchadd]

any ideas why joystick down not working? are eany components/chips that i should take a look at?

it must be something to do with the gameboard as if i change the board to a different it works ok.

[dabone]

Which game board are you switching to get it to work?

the whole cage? or a single board?



Later,
dabone

[rchadd]

Which game board are you switching to get it to work?

the whole cage? or a single board?



Later,
dabone

switched the single game board

i assume there is some componenet fault on the game board that is resulting in joystick down not being recognized in the game (or in test mode)

dont think it is a hardware issue with joystick itself as using a different game board everything is fine.

does anyone know which components on the game board are related to joystick down? which chip might be faulty?

[2600]

Do you have a multimeter?

I'd first check the joystick and wiring harness.

After that, I'd grab the schematic and go from there.

[Stingray]

Do you have a multimeter?

I'd first check the joystick and wiring harness.

Since it works with a different board it wouldn't be the stick or the harness would it?

-S

[ChadTower]

Not in isolation, no... but if that harness has a flaky pin on that particular signal line, it could be making better contact with one edge connector than the other. 

[rchadd]

i'll check the connector - maybe one of the pins is bent

[2600]

Man I'm slow.  2 replies before I could get a word in. 

After you check the wiring and stick, grab the schematics from the web.  It shouldn't be too hard to debug a joystick input with a multimeter.

[ChadTower]

i'll check the connector - maybe one of the pins is bent

Check the edge contact, too... it may need to be retinned.

[Ed_McCarron]

Never worked on a real one, but...

http://www.gamemanuals.net/download/e80ef5f7bbdddabadd69533fee8083c1/Gorf%20%5BParts%20&%20Operating%5D.pdf

Ungodly long link there... not sure how to embed url.

Start on page 50.  Looks like the joy is optical?  Find U1 - the LM339 comparator.  Check pin 2 to 5v and gnd and see if it changes states when the stick is moved down.  If you get the output there, move along until you lose it.   Think the next step is to the logic board, some kind of matrix happening there.  Hopefully you get lucky early on.

[rchadd]

the joystick and interface board must be working ok as works with a different game board. figure it is issue with the game board somewhere.

problem with working with gorf boards is that they are in the stupid cage which makes it impossible to make any measurements on any pins when it is being used.

http://arcadecollecting.xmission.com/pcbpics/p153.html

[paigeoliver]

the joystick and interface board must be working ok as works with a different game board. figure it is issue with the game board somewhere.

problem with working with gorf boards is that they are in the stupid cage which makes it impossible to make any measurements on any pins when it is being used.

http://arcadecollecting.xmission.com/pcbpics/p153.html

Just disable "up" as well, and your problem is solved!! 

I always just move left and right in Gorf anyways!

[Ed_McCarron]

problem with working with gorf boards is that they are in the stupid cage which makes it impossible to make any measurements on any pins when it is being used.
http://arcadecollecting.xmission.com/pcbpics/p153.html

Yuck.  Looked so easy in the schematic.

I wonder if they made an extension card for troubleshooting

[ChadTower]

Run the swap test 3 or 4 more times to further rule out a bad harness or edge pin.  It won't completely eliminate this chance, but it will make it less likely.

[dabone]

Try replacing the following on the game board.

R2, R18, C2

Or

R7,R23,C7

Then try U1 or U2.

(The or comes from the fact that the schematics call for Left and Right player inputs, I don't which one is player 1.)

Resistors R2 and R7 are 220ohm.

Resistors R18 and R23 are 27Kohm.

Caps are .1mfd

U1 and U2 appear to be MC14539B chips.

(Dual 4-Channel Data Selector/Multiplexer)


After these components the inputs share common lines/components.
One of those should fix the problem.


Later,
dabone