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ScuzzBlog: Diaries June 2024

Entry 19th June 2024: Post 1: Amiga Technologies A1200 - surprised and shocked.


Amiga Technologies A1200 - surprised and shocked.

In true scuzz fashion I just can't leave things alone if I become
troubled by an unresolved issue. So try as I may to leave the
A1200 with the busted hard drive alone, something just wouldn't
let me be. Something didn't add up.

One of the joys of the Amiga is no virtual memory. This means no
hard drive working as software as with the PC. The Amiga basically
loads everything into memory and then works from there, in essence.
So if a computer flatlines when there is no disk activity it cannot
be due to a failure of the disk.

So the other day when the machine crashed whilst doing routine tasks
that did not involve the hard drive [ no activity ], it could not
have been disk failure. The guru clearly said software error and
then flatlined and rebooted.

The hard drive failure was caused by a halting of the drive whilst
active. The validation was caused because the hard drive had been
halted whilst read/writing to the disk. The computer no longer knew
how big the drive was. That was a separate issue. The software
failure happened when there was no disk activity. So unrelated.

All this pointed to some kind of interrupt on the logic that was
sending out an incorrect signal. My gut reaction at first was for
capacitor failure. The machine is currently working, though now
back in store. I have to update the label on the base. Time to take
the lid off this problem, once and for all.

I have moved back my trusty Frankenstein A1200 with the hard drive
stuck out of the back on a ribbon. This machine is of two different
case origins, and at some time in its life was in a tower. Of any
Amiga destined for failure it would be this. She's a hero Amiga.

More on that later.

Can I first say that I do not take capacitor issues lightly. I am
quite rigorous in my checking for capacitor failure and take high
definition images on a regular basis. If I suspected a problem I
would act. Up to now I have only had one A600 and one A4000 fail.
Neither were recoverable, my failure for taking the eye off the
ball. I sense I may have a third on the way.

Amiga Technologies A1200 - surprised and shocked.

You know I'm always scratching myself on the label.

No wonder there is an exposed tip of a screw.

They screwed the faceplate/logo right thro.

I sense I may never have taken the shielding
off this computer. The metal tangs that are
bent over are same patina grey as the discoloured
shielding. The tangs are of the same age.

That is curious for me. Means the motherboard
has never been inspected in all the time she
has been here.

OK first problem is a missing screw from the
floppy drive. Hopefully the drive does not ground
from the screw to the motherboard.

I always record cable and ribbon arrangement
before removing.

And there we have it ... the red herring.

Or maybe a green herring. Let's see.

I was keen to check the RGB port pins.

The floppy drive is from the Escom era.

There were two screws in all missing from
the motherboard.

First stop will be the power to the floppy
and the LED lights to the keyboard.

At first I thought a creature such as
a spider had been living around the power
connector as there was sticky residue on the
motherboard edge next to the accelerator.

The truth was that the capacitor was leaking
and clearly running toward the trapdoor.

Note the corrosion to the adjacent components.

My heart sank as I discovered capacitors leaking
in a number of locations. I was very shocked.

You can see the path of the leakage and the
tell tale dusting of solder spots and corrosion
to legs on components. The dulling of tinning
was everywhere.

I was so surprised by the level of failure.
There can be no doubt what is causing the true
failures of this machine.

I have not seen anything like this before on
any of my Amiga 1200s.

Kinda knocked me for six.

I do sense this is Coopers ducks for this 1200.

So I carefully put things back together.

She didn't at first boot from the hard drive.

After a soft reboot she was fine.

WB 39.29 and Workbench 3.0 got me to thinking
I have another project for tomorrow.

Enter Frankenstein.

OK I moved into this room and took a peak
into Frankenstein's innards. I wanted to
take a quick peak and see if her capacitors
were in the same state.

Note that young Frankenstein here gets well
and truly hammered. She is used for all my
ADF files. She has the SurfSquirrel and ZIP
drive and is on most every other day.

Note also that she has no shielding and so is
bombarded with food debris, dead skin, dust
and hairs that get blown past the keyboard.
I didn't clean the board.

The drive is out back of the case off a ribbon
Don't ask !!

Ignoring the debris there was no evidence
of capacitor spillage.

Adding brightness shows no dulling of
any of the component legs.

You have to imagine this image without
the hairs and dust and there really is no
degrading of any components.

The area around the power connector to the
floppy and keyboard header was clear of
any capacitor residue. The component legs
again were sparkling bright.

That is the GVP Jaws... Bite your head off man !!

I couldn't find any leakage around capacitors.
And so I was somewhat relieved that the damage
has been contained to one A1200, thus far. I will
now undertake a thorough check on others.

There really is no excuse for not recapping these
machines. My only defence is that they are only
needed until I die. So I'm prepared to take the
risk. Kinda a selfish view, but hey, my collection
and I only got the things for me. What happens after
can be someone else's problem.

I have maybe a few years to go give or take a decade or so.


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Last updated 19th June 2024

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