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Old 31 July 2009, 18:37   #1
piemmeweb
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Problems with my amiga 4000

Hello, i'm experiencing problems on my amiga 4000 + 16MB RAM + Cybervision 64 + HDD 80GB + DVD-ROM + KICK 3.1 + BUSTER 11 + OS 3.9:

When power up, the power led flashes rapidly and yellow screen appears, the computer won't boot.
If I turn the power off and power on again, the same problem appears... but if I reset by keyboard for two or three times, the computer boots and works fine.

Can you help me?
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Old 31 July 2009, 19:08   #2
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Had similar problems with mine last week.

Try re-seating the CPU card and ram. If that don't work remove all fast and put simm in one at a time.

Check all capacitors both on the motherboard/cpu card. Especially the one's rated at 22uF/16v.
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Old 31 July 2009, 19:15   #3
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Quote:
Originally Posted by Paul_s View Post
Had similar problems with mine last week.

Try re-seating the CPU card and ram. If that don't work remove all fast and put simm in one at a time.

Check all capacitors both on the motherboard/cpu card. Especially the one's rated at 22uF/16v.
Well, I will try, thank you , but... how to check the capacitors?
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Old 31 July 2009, 19:18   #4
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Check the second picture down on this webpage... (Leaking SMD capacitors bit)

http://amiga.serveftp.net/audio_repair.html

You're looking for any form of corrosion/leaking on the board. Have you also removed the battery as they are well past their sell by date?
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Old 31 July 2009, 19:24   #5
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Quote:
Originally Posted by Paul_s View Post
Check the second picture down on this webpage... (Leaking SMD capacitors bit)

http://amiga.serveftp.net/audio_repair.html

You're looking for any form of corrosion/leaking on the board. Have you also removed the battery as they are well past their sell by date?

The battery has been removed some years ago, I seen on that webpage but I have no audio problems at this time... I will need to look at all capacitors on the mainboard... uff!!!
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Old 31 July 2009, 19:35   #6
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Could be duff ram if the caps check out but I'd replace them all anyway (caps) as the factory ones are carp!
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Old 01 August 2009, 09:18   #7
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New Test

I tested rams and they works fine... but I'm thinking... I removed the battery some years ago and not replaced it. I replaced it about one week ago to have a real time clock and after two days the computer falls in problems... need I to remove the battery again? can be it the cause????

Diagnosis:

first attempt: power on: power led fixed, hdd led fixed , no boot
second attempt: reset by keyboard: power led flashes, hdd led normal, yellow screen, the computer reboot itself 3-4 times, then workbench starts, but mouse freezes or no signal on the cybervision vga card
third attempt: reset by keyboard: power led flashes, hdd led normal, yellow screen for 2 seconds, the computer boot normally and all works fine.

After the third attempt I can power off or reset by keyboard, the computer boots normally but if I power off and wait 15-20 seconds, I need to come back to the first attempt

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Old 01 August 2009, 15:23   #8
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Solution!!!!

Hello again, maybe I found the problem:

the problem should be the 2mb chipram simm, because when i pulled off it and substituted with a 1mb simm , the result is no yellow screen and the machine works fine.
But it's not boots at first attempt, I need to reset by keyboard, but no yellow screen!

well, anybody can help me to find an appropriate 2mb chipram simm? I tried some 2mb simms but green screen...

I'm looking on ebay but don't know what can be good for me... thanks a lot!
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Old 01 August 2009, 15:46   #9
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A yellow screen means that an exception has been generated during the early bootstrap process, prior to the "regular" exception handlers being loaded.

Usually two things can cause this:
1. Malfunctioning hardware that is sending interrupts before being initialized (not likely).
2. Memory issues causing the early startup code to generate an exception, i.e. odd address error.

The green screen means that there was < 256K of chip RAM detected. The chip RAM detection writes a '0' at memory location 0, then continues to step up in 4k increments, storing a # there & reading it back to verify, then checking memory location 0, until either 0 gets trashed (indicating that there is incomplete address decoding) or it gets to $200000.

The presence of a 1MB SIMM, as opposed to a 2MB SIMM, shouldn't mean all that much to the bootstrap process (although you would only have 1MB chip RAM instead of 2MB).

In either case, it does sound like you are having memory issues. Hopefully someone with A4000 hardware experience can point you in the right direction with regards to compatible SIMMs.

Edit: Try disconnecting the DVDROM and see if that helps with the "no boot on first powerup" issue.
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Old 01 August 2009, 19:59   #10
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Also bad capacitors on the power supply and over the motherboard can cause such behaviour due ripple in the +5V line.

A heavily or over loaded PSU can do the same thing.
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Old 01 August 2009, 22:26   #11
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Well, I mounted an 8MB SIMM instead 2MB simm and now can have 2MB chipram but there's another problem:

The computer boots at first attempt, the workbench loaded but freeze at the end I do reset with keyboard and the computer boots and works fine...
can be a problem for the 8mb simm instead 2mb simm?

Is there a friend that can take a look inside ebay to find appropriate 2mb simm that I can to buy?

many thanks!
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Old 19 August 2009, 15:01   #12
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Update:

I replaced all capacitors on mother board, accellerator board and power supply, but the problem still remain.

step 1: On power-up the power led flashes quicky and system reboot itself for 4-5 times;
Step 2: after it boot the workbench 3.9 but reboot itself;
step 3: after it boot the workbench 3.9 and works fine

If I reset the system by keyboard on power-up, the power led doesn't flashes anymore and go to step 2

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Old 19 August 2009, 19:39   #13
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I saw a thread on here sometime ago with a very resemblant defect on an A600.

Was a defective SMD capacitor near the reset circuit. I think I need to search on the forum to find it.
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Old 19 August 2009, 20:56   #14
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Quote:
Originally Posted by rkauer View Post
I saw a thread on here sometime ago with a very resemblant defect on an A600.

Was a defective SMD capacitor near the reset circuit. I think I need to search on the forum to find it.

I replaced ALL capacitors inside my amiga 4000, including in the power supply...
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Old 20 August 2009, 00:08   #15
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I mean those very little SMD ones, not an electrolytic piece.
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Old 20 August 2009, 15:13   #16
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Quote:
Originally Posted by rkauer View Post
I mean those very little SMD ones, not an electrolytic piece.
UFF, I cannot test and replace all caps on the mainboard!

BUT...

I seen that sometimes the workbench load but cannot start properly, the system says: unable to open DATATYPES.LIBRARY V39 , then no icons on the desktop and self reboot after some seconds...

What is that?
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Old 20 August 2009, 21:05   #17
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Quote:
Originally Posted by piemmeweb View Post
UFF, I cannot test and replace all caps on the mainboard!

BUT...

I seen that sometimes the workbench load but cannot start properly, the system says: unable to open DATATYPES.LIBRARY V39 , then no icons on the desktop and self reboot after some seconds...

What is that?
That sounds like you aint got enough memory to load everything workbench needs.
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Old 20 August 2009, 23:16   #18
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Quote:
Originally Posted by FOL View Post
That sounds like you aint got enough memory to load everything workbench needs.
I have 2MB chip memory + 16MB fast memory (4x4MB SIMM) onboard, I reaches the maximum that A4000 can support ...

but seen that in workbench I have about 1.8MB chip ram and about 9MB fast ram available, I suppose that's normal... or not???

Please note that I receive that error the first attempt when the workbench loaded; after that error the system reboot itself and all works fine at last...

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Old 20 August 2009, 23:24   #19
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Quote:
Originally Posted by rkauer View Post
I saw a thread on here sometime ago with a very resemblant defect on an A600.

Was a defective SMD capacitor near the reset circuit. I think I need to search on the forum to find it.
How to find the reset circuit on the A4000D mainboard?
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Old 21 August 2009, 00:39   #20
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Maybe you problem is not hardware-wise.

Can you print here the 4k's startup-sequence? Plus which icons are in the WBStart drawer? Plus the icon preferences inside Prefs: ?
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