Weird `````````````` effect

[X-ray]

Okay guys and gals I dunno if this is a hardware or software problem, but before I dismantle this A4000T I want to know if anybody had this kind of nonsense before:

I switched on earlier and the Miggy booted fine but when I went to move the mouse it was frozen. Keyboard also, couldn't CTRL Amiga Amiga. When I reset, I got all sorts of coloured screens, grey, blue, green, red, cycling through then black for 5 seconds then the familiar mutlicolour stripe reboot of the CS MkII. After that, no problem to reset or reboot, but now every now-and-then if I'm working with something that can take keyboard input, I get the ` typing by itself, it keeps on going until the line is full or until I press any key on the keyboard. I've checked and no keys are stuck, all connections into the tower secure.

What the hell is this?

[adz]

My first thoughts would be that one if the CIA's is a tad flakey, did you just purchase the machine?

[X-ray]

he he no, its ironic I was just saying on another thread how somebody blew both my CIAs about 5 years ago and how I had them both replaced, and no trouble from them at all since then.

No, this has been my Amiga all along, since 1996. I hope this isn't a CIA problem. Is this ```````````` a typical CIA problem?

[adz]

Well I had a similar problem with my A2K, whenever you pressed button one of any device attached to the 2nd user port, the machine would freeze and upon reboot, I would get all kinds of funny screens, if I shut it down again, all would be fine until you pushed button one again. Mind you I did also notice some oddities with the keyboard during normal operation as well. Once I replaced both CIA's the machine was perfect. Not sure how you would fare replacing the CIA's on your A4KT as they are surface mounted, might be a tad costly, so I would examine every other possibility first.

[ent0mbed]

What are the odds that you can do something simple to troubleshoot like swapping out the keyboard with another one.  Even if the keys not stuck it doesn't mean a contact can't be triggering on its own.

[KennyR]

My A1200's keyboard has a loose connector (a tower keyboard adaptor). Whenever the keyboard loses power for even a fraction of a second it will short and give `````````````````.... Longer, and the caps lock will just flash and the keyboard will refuse to do anything - until I unplug it and replug it, sometimes with a power off needed.

You must have a wobbly connector in there. Secure it and the problem should go away.

[Jope]

Usually that problem comes if you switch data and clk in the keyboard connector, but this time it probably isn't a case of that.

Like said before, check the DIN connector's solder joints on the motherboard and try another keyboard.

[X-ray]

Come on gents, give me a little credit, I tried the keyboard. Its not that. In fact it happens even if the keyboard isn't plugged in.
I'm beginning to think this is a software problem

[X-ray]

Just got even more weird....I now have the dubious pleasure of seeing the purple screen with the disk, after all these years...
Right, that means I gotta open the old girl up.

[A4kT]

I have an A4000T and have seen this problem as well as the purple screen.
First I would try re-seating the daughterboard  module for the CPU.

Then - if you have a Cyberstorm installed, re-seat any memory SIMMS -maybe try booting with only one SIMM at a time.

Make sure that the plastic legs under the CPU module go through the holes in the board., There should be a satisying "thunk" when you re-seat the CPU module.

Check or remove any slow motherboard memory - re-seat them.


Good Luck.

[Piru]

Usually that problem comes if you switch data and clk in the keyboard connector

Indeed. I got this exact effect when I first accidently had the CLK and DAT lines swapped with my  keyboard hack.

[X-ray]

You guys have been a great help, I dismantled the whole thing and took the CS out and reseated all the simms. So I now have got rid of the weird screens on startup, and also the weird phantom key presses, but I have now swapped one problem for another:

The left mouse button no longer works...interestingly it clicked once when I launched a program from a Toolmanager dock, but hasn't worked again. Tried a different mouse - same deal. This is getting frustrating, chaps. I suppose I had better open it again and run it open (feel which CIA gets hot if any). I dread another CIA being bust.
It would be a shame if I couldn't fix it because I have held onto this Miggy for all these years and have been proud that it all still works.
While I'm checking it again: does anyone know where I can send the mobo to if indeed I do need a new CIA chip?

[Castellen]

The mouse problem can be caused by a bad shift register (responsible for data to and from mouse & joystick ports).

The `````` problem is usually caused by either the KB data or KB clock line not working, or one of them being open circuit.  A faulty CIA can definately cause this, but so can a few other components in the KB signal lines.

As for repair, if you're on the England side of the planet, then Amiga.fr (France) is a good option.  A few places in USA are said to be good, but I can't quote any names off hand.
If you're around Australasia, you can send the bare MB to me in New Zealand for repair.  I usually fit SMD sockets when doing CIA replacements so it's much easier to replace them in the field if required in the future.

[X-ray]

Castellen

I think that's a great idea, providing sockets for future CIA chips. If the french guy can't do it, I'll send it to you (assuming I can't find the problem). Can you pm me some contact details and an idea of cost? Weird thing is the joystick button DOES work and I thought that a left button failure is only a CIA problem if the joystick fire button is also dead. Am I wrong about this? If I'm not wrong, any suggestions about what else it can be, because I can't see anything wrong here physically.
BTW the ```````````business has stopped (at least for today).

[Brian]

I had the smae problem with auto input of ````````` and it turned out to be a bad keyboard so a new keyboard solved that problem.