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Old 28 March 2017, 19:15   #1
macce2
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Strange A4000 problem( s)

Occasional character trash on cli/ shell, floppy drive problems... Any ideas ?
Psu ? Processor card ? Some custom chip ?... ? ��

Last edited by macce2; 28 March 2017 at 19:49.
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Old 28 March 2017, 20:28   #2
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Battery damage or leaking caps? They can cause all sorts of weird problems.
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Old 28 March 2017, 20:50   #3
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I think it may not be a battery leakage damage, because the battery had almost no leakage and was recently removed. Maybe I should check the A3640 processor card for possible leakage and/ or loose connection... ?!
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Old 29 March 2017, 15:09   #4
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One of the CIAs handles the keyboard as well as a number of floppy-related functions. I can't remember which CIA it is on the A4000 (ut's U7 on the A1200), but that's where I would start.
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Old 30 March 2017, 03:18   #5
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Thaks for your help I think I' ll continue testing coming week end. I have been thinking, why does Sysinfo still say " clock found", even though the battery is removed ?
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Old 30 March 2017, 08:49   #6
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The clock hardware is still there, but it won't hold the date when the battery is missing.
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Old 31 March 2017, 03:16   #7
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Quote:
Originally Posted by Daedalus View Post
One of the CIAs handles the keyboard as well as a number of floppy-related functions. I can't remember which CIA it is on the A4000 (ut's U7 on the A1200), but that's where I would start.
What this guy says. U350 (the one at the edge of the board) handles keyboard and floppy stuff and there's a couple electrolytic caps in the area that are likely to have leaked at some point. Also FIR0 and FIR1 which are, what third mouse or joystick button?
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Old 31 March 2017, 09:50   #8
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Quote:
Originally Posted by grelbfarlk View Post
...U350...
Thanks!

Quote:
Also FIR0 and FIR1 which are, what third mouse or joystick button?
Joystick / left mouse buttons on port 0 and port 1
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Old 31 March 2017, 13:13   #9
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Thanks!



Joystick / left mouse buttons on port 0 and port 1
Riiight right. I'm going to go sit over here now.
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Old 31 March 2017, 20:37   #10
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I have been away, but will check my machine soon. If I remember right, mine was rev. B ..
Could the possible cause of problem be Cpu card's loose connection...?!

If U350 (?) is faulty, could it be replaced ?

Oh, I forgot to mention that the character trash I mentioned earlier consisted of only one character..
was it '''' or something ´´´´´´´´´ ?!

Last edited by macce2; 31 March 2017 at 20:45.
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Old 31 March 2017, 22:31   #11
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I have been away, but will check my machine soon. If I remember right, mine was rev. B ..
Could the possible cause of problem be Cpu card's loose connection...?!

If U350 (?) is faulty, could it be replaced ?

Oh, I forgot to mention that the character trash I mentioned earlier consisted of only one character..
was it '''' or something ´´´´´´´´´ ?!

Well that's not likely that it is a loose CPU connection. Easiest thing to check is trying another keyboard. But if you say you have floppy funkiness between the two symptoms that sure sounds like the CIA chip. Which is soldered on.
How about some high res pictures of the area? Again my guess is a leaky cap leaving some electrolyte on the board which is shorting something. You could just try cleaning the area with some 91% Isopropyl alcohol that you can pick up at the pharmacy, note: let it dry first.

Using your highly detailed account of the condition of the system and the problem described, I have recreated a very accurate representation of the what this corner of your motherboard looks like:
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Old 31 March 2017, 23:05   #12
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My rev. B board had the same symptoms caused by leaked capacitors highlighted in the picture above.
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Old 31 March 2017, 23:07   #13
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LOL, it's probably pretty close to the truth alright! Yes, check that whole area for corrosion due to leaking capacitors. If the chip is faulty it can be replaced, but it's more likely to be corrosion in the area than the chip itself failing. The ` character is keycode 0, so that could be a problem with the CIA constantly thinking the button is held down. It's a good idea to check another keyboard, but given the other issues you're having with the floppy drive, I'd strongly suspect some sort of board damage in the areas indicated in the image above.
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Old 01 April 2017, 14:48   #14
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First, Many thanks to all of you!
Then, I must tell you I' m using a Gateway 2000 keyboard with homemade adapter.
I think I should try with a different one first, and make sure the adapter is ok..
Would an old A2000 keyboard work ( with adapter unit) ?
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Old 01 April 2017, 17:27   #15
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Yes an A2000 keyboard would work with a DIN to PS/2 adapter.
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Old 03 April 2017, 20:09   #16
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@macce2: If you are still having problems with your motherboard, I totally recommend asking Hese to work on it - he diagnosed and fixed my A4000 MB (battery damage and other stuff) and now it's working beautifully. And he's in the same country as you!
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Old 10 April 2017, 23:58   #17
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At last.... Today I tested my machine after a while.
Before powering up, I checked the keyboard adapter connection seemed ok. After some reboots and a few hours use, everything was ok, expect for some game disks didnt boot, just black screen.
I have usually used external floppy drive,
and because it started to have problems
I removed it. I have opened it and tried to repair it before.
I think it sometimes caused my machine suddenly reboot ( wb use).
- So I must ask you: Could a faulty external floppy drive and/ or port cause problems I mentioned before ?
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Old 09 May 2017, 23:54   #18
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Ok 2 days ago, I opened my machine , removed the drives, the daughter board & Zorro cards, and the processor board. I did this mainly because I had some problems with my Picasso IV card. It lacks the piece of metal that is tightened to the back of the machine with a screw, ( whats that word, er ? ), and because of that the card tended to move slightly downwards and that was causing problems . I did the first aid by inserting a small riser piece, with blu- tack, to a chip, just below the P4 card.
So, a little away from the main topic, but is it ok to use blu- tack om the motherboard etc ?

Now back to the main topic. I checked the motherboard for possible damages / leaks etc, but didnt notice anything. However, Im not expert in electronics and didnt use magnifier, so it is possible there was something wrong on the motherboard.
However, the keyboard/ floppy problem is gone.
I think the reason for problems was bad connection with the keyboard& adapter and/ or the kb port. My external floppy drive also had some problems .
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