A1200 possible CIA fault

Hi

I have just bought another A1200 motherboard Rev 1D4.

I'm having quite a lot of problems with the machine, half of the keyboard doesn't work and seems to dead.

When I boot from CF hard disk, I have noticed the floppy drive seems to make a lot of noise and says DF0???, in workbench, not all the time though, but it is reading discs ok.

The last problem is the right button on the mouse doesnt work all of the time, it is a working mouse, tried on another 1200.

I have another spare 1200 I can fit the keyboard into to test, not tried yet.

I'm just wondering if anyone has any ideas, before I tear it to bits.

Thanks

[roy bates]

it could be the cia causing problems with the floppy,but if you have a second 1200 try the floppy from that one first to make sure its not the drive.


as for the keyboard also try the other keyboard in it as it may be the end of the ribbon cable causing problems.(when you unplug it you will be able to see through the carbon stip if its worn out by holding it upto a light source)

and then you can go from there as far as repairs go.checking for micro fractors on the ics bad solder joints etc


with the mouse button it could be a resistor on the motherboard(cant remember which one at the mo or a broken pin in the 9 pin socket a bad solder joint etc,whatever happens youll be taking it apart anyway,so you may as well carefully examine the motherboard for bad parts etc


oh and before i forget welcome to eab.

[whitebird]

Hi,

I had problems with keyboard where some tracks lying on the two plastic plates holding the contacts were broken. If the problem is mechanical, you may identify some rows, columns that are not working and check against the keyboard schematics.

Check not only the CIA but also U13 which is the keyboard controller to see if it is not badly soldered.

Looking at the schematics, it can be seen that the right mouse button is connected to paula, not the U7 CIA. So if the problem is "bad component" it would mean you may have problems with two components U7 and U3 (paula) which seems a bit strange.

Check everything with multimeter

Thanks for the replys, I'll try the keyboard and floppy from the other 1200 first and check board with meter, I'll post back what I find

Ok, after some testing, the keyboard membrane is damaged and thats why the keyboard doesnt work properly, its actaually black along quite a lot of traces under the spacebar and other keys, so I've got a replacement membrane on the way.

Floppy drive does have problems even though its reading, I'll open it up and try to clean it.

God knows whats going on with the mouse, I've tried another on this Amiga and it seems to be happy with it, maybe the original mouse I tried is faulty.

I also thought I had a graphics fault on the machine, when running the State Of The Art demo on WB Classic I was getting graphic corruption, but it's the same on the other Amiga with the same CF card, so it must be either CF card or maybe I've set the Max Transfer wrong, or possibly a bad install of the operataing system.

Think I've jumped to conclusions to soon when I got the Amiga and its not as bad as it seems.

Hopefully I'll get it all sorted.

[prowler]

Hi edimax,

Is your A1200 a Commodore or Amiga Technologies model?

Originally Posted by prowler

Hi edimax,

Is your A1200 a Commodore or Amiga Technologies model?

It's a Commodore.

Replaced the keyboard membrane tonight, keyboard's all good now, going to look at the floppy over the next few days.

[prowler]

Originally Posted by edimax

It's a Commodore.

Thanks. The reason I asked is that the Amiga Technologies models have a compatibility problem with some floppy disks, but the Commodore models do not.

Now, what is the make and exact model of the (DF0:) floppy drive fitted to your A1200?

It's a Chinon FZ-354

I've have found out whats going on with the floppy, everytime I turn the machine on without CF hard disk in, obviously it tries to boot from floppy, it tries about three times and gives up.

If I boot off the Hard disk the floppy shows df0????

I was researching the problem before and it seems to be down to two little prongs inside the drive, think it's the floppy exchange sensor.

Anyway I spayed a very small amount of WD40 on to the prongs and worked it in.

The drive now checks for floppy discs, still gives the df0???? now and again, I'll try the WD40 on it again.

But its looking a lot better.

[prowler]

Originally Posted by edimax

It's a Chinon FZ-354

Well, that's one of the the correct drive types. So it shouldn't give you any trouble as long as it's working properly

Originally Posted by edimax

I've have found out whats going on with the floppy, everytime I turn the machine on without CF hard disk in, obviously it tries to boot from floppy, it tries about three times and gives up.

If I boot off the Hard disk the floppy shows df0????

I was researching the problem before and it seems to be down to two little prongs inside the drive, think it's the floppy exchange sensor.

Anyway I spayed a very small amount of WD40 on to the prongs and worked it in.

The drive now checks for floppy discs, still gives the df0???? now and again, I'll try the WD40 on it again.

But its looking a lot better.

It sounds like you might be onto something there...

Depress the prongs with a small screwdriver several times to work the lubricant in before trying it again.

I havent had as much time as I would have liked to spend on the A1200.

But tonight, I have sprayed a little bit more WD40 into disc exchange sensor and used screwdriver as suggested to work it in and the drive is working 95% of the time as it should be.

I think it will be 100% with time and more use.

[prowler]

Originally Posted by edimax

I have sprayed a little bit more WD40 into disc exchange sensor and used screwdriver as suggested to work it in and the drive is working 95% of the time as it should be.

I think it will be 100% with time and more use.