Anyone really can give me a hint on this subject.

Now i got the diskdrive working.

My problem is the joystick port is faulty simple check from basic.

Stick(1) returns 3 with no joystick plugget
it also returns 3 if joystick insertet but not touch

it returns 0 if joystick press left
it returns 3 if press right

I didnt test if the firebutton works.

It must be a bad component some where any hint which one

The psg seems to work fine.

Maybe its the special spectravideo chips, they were made only for use in svi738, i think. If those are faulty its very hard to repair because its no standard chips.

Any one ?

-Claus-

As there seems to be no one other, I try to help you.

First of all there is no such thing as "special spectravideo chips" in your computer. :-) I'm also almost sure, that there is nothing wrong with your chips if Joystick port 2 is working fine.

I suggest, that you take flashlight and check your joystic port 1. For me the problem seems that pins 4 and 8 are somehow touching each other. They are located physically next to each other so it seems logical. If the port is ok from the outside, check the inside. It might be a screw from the keyboard that has dropped off and sort circuited these pins or something.

With multimeter it should be easy for you to check if my diagnose is correct or not.

Hi

Actually SVi 738 have two special made chips. In the past i had a SVI738, but in some way i burned one of those chips, so the Cartrigde slot didn work. Henrik Gilvad made a add-on to one of those Spectravideo chips, so it can work with cartrigde again, but the SCC sound didn work it worked but the sound was very messy, then i sold the SVI738 back to him, and bough his A1ST turbo-R So it is true there are two special Spectravideo-made chips in that mashine. Today i will check, the port from outside noting is wrong, i can even plug in a joystick without "FORCE". Inside looks fine as far as i can see, but i take a better check later.

Anyone knows what electronc to controll the Joystick ports ? Someone sugested the PSG?

Or maybe the Z80 I/O ?

-Claus-

AFAIK the MSX PSG has some lines tied with the joystick ports; but I'm not sure if there're more ICs involved. Usually this kind of device suffers mechanical problems; so the way suggested by nyyrikki is the most reasonable; check first the continuity of every pin with a multimeter and be aware that most times the broken bit is hard to see

hello

i checked in side and out side

no connection between 8 and 4

So must be some damaged electronic that thinks there are a connection

to be complete sure i just resolded alle the pins

no diffirence

just checked, firebutton works too and up and down works too

-claus-

now i even changed the joystick port, i desoldered the old one, and soldered an old one from a Memotech MTX

The soldering seems very ok, no shortcuts still same result

Firebuton works.

Joystick port #2 seems to work 100%

Keyboard also.

There are some restores next to the joystick port, can it be a bad resistor?

-Claus-

Quote:

and soldered an old one from a Memotech MTX

I really hope that the Memotech was a broken one...

Maybe broken tracks?, have you follow the tracks testing their continuity?. About the resistors, you can also check if they are blowed.

Yes of cause, the MTX was a spare one i have one working cause that is my first computer.

My History of homecomputers.....
Memotech MTX 512
SpectraVideo SVI 328
Yashika YC-64 MSX1
SpectraVideo SVI738 (Modified to MSX2 with 256kb)
Panasonic Turbo-R A1ST

And then PC's.

Ok, if you are sure, that the connector is ok then we have to take one step further. Because Joystick port 2 is working fine this means, that PSG is ok. (same pins are used to read joystick 1 & 2) This means that only possible broken chip is IC47 (LS157) and I think that you have to replace that.

Before you start disconnecting this chip I suggest that you measure if there is a difference in input and output while reading joystick 1. The input and output state should be same between pin 14 (from joystick 1 right) and pin 12 (joystick X right to PSG)

If you want to take a look of the schematics, they can be found here:
http://www.msxarchive.nl/pub/msx/mirrors/hanso/hwmodsetc/svitechref.pdf

This stuff is on page 9

Bækkel!?

I've got most of the spare IC's for the 738, also the 2 special Spectravideo chips if you need 'em at a resonable price

Go Burgerklubben!

Hey I have actually a bit better idea... this way you don't need to replace the chip...

Cut the lines that are going to IC47 pins 12,13 and 14

Take a jump wire and connect these to same pins (12,13,14) in IC48

This should fix the problem.

Thanks NYYRIKKI i will try that

To Algorythms yes i am Mr. Bækkel yes and Brugerklubben rocks, but that is in the past I lost almost any contacts to MSXBrugerklubben. Btw do i know you ?

Greetings from Claus Bækkel = CrazyBoss

bye bye.

Uuuuummm....maybe the originl fault was a illegal use of PSG#7

What is that PSG#7 ?

I guess I know you better than you know me because of the Syntax articles. I'm Dan Isak Arneson from Norway. I attended the Norwegian fairs.