Amiga 600 RF shield rust/oxidation question

superrune · 07 October 2018, 16:47

Hi! I am new on this forum, and I registered because I have some questions regarding an Amiga 600 I am trying to refurbish. I hope you can help me

I purchased this Amiga a week ago. It will be my first since I was a teenager, so I am looking forward to try it out. But first I wanted to check the interior to see if everything was OK. It looked good on the outside, but had some severe rust spots in many places, and the lower RF shield had the worst damage. This is how it looked when I took it apart:

I have soaked the rusty parts of the shield in WD-40 and scraped it pretty vigorously with a steel brush. I managed to get all the red rust away, but I am left with this:

These black spots appear to be raised in some areas, recessed in others. In some places it appears to be like spots on the shiny metal itself. Is this also rust? Should I remove it as well? The metal brush does not seem to get it off though, so I am considering going at it with my dremel!

Hope someone can give me a couple pointers - thanks!

Solderbro · 08 October 2018, 20:42

These dark spots are deep oxidation, what will not grow if the metal is kept dry for now. Have a few in my A600 too, did the same clean up and put a bit of hard wax onto it as finish.
At all your result look good for me.

Solderbro

superrune · 09 October 2018, 08:56

Quote:

Originally Posted by Solderbro

These dark spots are deep oxidation, what will not grow if the metal is kept dry for now. Have a few in my A600 too, did the same clean up and put a bit of hard wax onto it as finish.
At all your result look good for me.

Solderbro

That's great news! Thanks for taking the time to answer. Cheers!

nexus · 09 October 2018, 09:09

good comparison of rust removers
[ Show youtube player ]

project23 · 09 October 2018, 12:42

If you're obsessed about the dark spots, and want them gone, you might (read might) Be able to get rid of these using electrolysis.

I've used a similar process to remove rust from automotive parts. No mains electricity is necessary just a big car battery, and an appropriate bit of waste metal that the rust will 'move' to.

The pits will remain - the Alu is gone - but they wont be black afterwards.

I've done a quick google and you can do this with Aluminium, which i think (???) the shield is made of. Don't know what it would do to the finish - its also pretty thin so some of the spots may turn into holes.

Anyway, thought i'd put it out there if you really are the obsessive type.

But honestly, i think it looks great compared to how it used to, so like it and love it!

John

project23 · 09 October 2018, 12:45

By the way WD40 is a water repellent and lubricant - it will do nothing for oxidation and stuck parts (its a common myth). When it works to free stuck parts, its just because it added lubrication. So all the work to remove the oxidation you did came from the steel wool. Good honest hard labour!

If you have a stuck part - you need a good penetrative oil.

A good electrical contact cleaner spray may help with the dark spots. You'd have to research it - i'm curious myself. I've got some similarly looking shields.

Just an aside!

John

Jope · 09 October 2018, 13:12

.. and it's a terrible lubricant too for anything more than getting a stuck fastener turning. For a permanent application, you should use something made for the spot you're putting it on. :-)

ajk · 09 October 2018, 13:33

I don't think the shield is aluminium, it wouldn't have rusted if it was. I think it's just thin, possibly tin-plated steel.

Hewitson · 09 October 2018, 17:55

It might just be poor quality aluminium. Stainless steel isnt meant to rust either, but I have seen shit quality (otherwise known as Chinese) stainless steel rust countless times.

nexus · 09 October 2018, 18:01

chinessium*

WD stands for water displacement
PB Blaster is another old school

Jope · 09 October 2018, 18:22

Quote:

Originally Posted by ajk

I don't think the shield is aluminium, it wouldn't have rusted if it was. I think it's just thin, possibly tin-plated steel.

I'm also under the impression that it is tinned steel.

ajk · 09 October 2018, 18:48

Quote:

Originally Posted by Hewitson

It might just be poor quality aluminium. Stainless steel isnt meant to rust either, but I have seen shit quality (otherwise known as Chinese) stainless steel rust countless times.

I have seen stainless steel rust too, but it's not quite the same thing. Stainless steel is still mostly iron, it's just alloyed with chromium which is supposed to protect it. But aluminium is an entirely different metal and can't really rust in the same manner. Also, the shielding material is highly magnetic (just tested with an A1200 I have opened up

).

project23 · 09 October 2018, 19:35

Yeah I don't know why i thought of alu, when it rusts so badly.

If its just steel, try a bit of coke (as in cola) on a scrubbing sponge. Works wonders for old car fenders (but might not be enough for this)

nexus · 09 October 2018, 20:08

vid above shows coke sucks at rust
good enough when in a jam to get batt corrosion in your car terminals though

ElectroBlaster · 10 October 2018, 12:26

These sheilds are somekind of thin tinned steel designed to resist corrosion, hence why they turn that scabby black!

If rust becomes too much, it takes over and everything starts rotting.

I cleaned up an A1200 shield by going in the hard way and using wet-n-dry sandpaper, water and wire wool. It will never look perfect but I managed to get the back row (port area) looking very nice!

The best way is to get the sheilding stripped and re-coated. Somebody on the Amiga facebook group has been doing this and the results are 100%, almost like stock. Reminds me of when an Amiga was brand new almost

project23 · 10 October 2018, 12:49

Do you have a link for this at all?

Is the strip and recoat process both electrolysis, coz I still have a setup in the shed I might play with hahaha.

07 October 2018, 16:47	#1
superrune Registered User Join Date: Oct 2018 Location: Oslo, Norway Posts: 16	Amiga 600 RF shield rust/oxidation question Hi! I am new on this forum, and I registered because I have some questions regarding an Amiga 600 I am trying to refurbish. I hope you can help me I purchased this Amiga a week ago. It will be my first since I was a teenager, so I am looking forward to try it out. But first I wanted to check the interior to see if everything was OK. It looked good on the outside, but had some severe rust spots in many places, and the lower RF shield had the worst damage. This is how it looked when I took it apart: I have soaked the rusty parts of the shield in WD-40 and scraped it pretty vigorously with a steel brush. I managed to get all the red rust away, but I am left with this: These black spots appear to be raised in some areas, recessed in others. In some places it appears to be like spots on the shiny metal itself. Is this also rust? Should I remove it as well? The metal brush does not seem to get it off though, so I am considering going at it with my dremel! Hope someone can give me a couple pointers - thanks! Last edited by superrune; 07 October 2018 at 19:33.

09 October 2018, 12:42	#5
project23 Used Register Join Date: Jul 2018 Location: Liverpool Age: 41 Posts: 437	If you're obsessed about the dark spots, and want them gone, you might (read *might) Be able to get rid of these using electrolysis. I've used a similar process to remove rust from automotive parts. No mains electricity is necessary just a big car battery, and an appropriate bit of waste metal that the rust will 'move' to. The pits will remain - the Alu is gone - but they wont be black afterwards. I've done a quick google and you can do this with Aluminium, which i think (???) the shield is made of. Don't know what it would do to the finish - its also pretty thin so some of the spots may turn into holes. Anyway, thought i'd put it out there if you really are the obsessive* type. But honestly, i think it looks great compared to how it used to, so like it and love it! John Last edited by project23; 09 October 2018 at 12:48.

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08 October 2018, 20:42	#2
Solderbro Registered User Join Date: Jun 2018 Location: Hamburg Age: 55 Posts: 56	These dark spots are deep oxidation, what will not grow if the metal is kept dry for now. Have a few in my A600 too, did the same clean up and put a bit of hard wax onto it as finish. At all your result look good for me. Solderbro

09 October 2018, 09:09	#4
nexus Registered User Join Date: Aug 2017 Location: USA Posts: 728	good comparison of rust removers [ Show youtube player ]

09 October 2018, 12:45	#6
project23 Used Register Join Date: Jul 2018 Location: Liverpool Age: 41 Posts: 437	By the way WD40 is a water repellent and lubricant - it will do nothing for oxidation and stuck parts (its a common myth). When it works to free stuck parts, its just because it added lubrication. So all the work to remove the oxidation you did came from the steel wool. Good honest hard labour! If you have a stuck part - you need a good penetrative oil. A good electrical contact cleaner spray may help with the dark spots. You'd have to research it - i'm curious myself. I've got some similarly looking shields. Just an aside! John

09 October 2018, 13:12	#7
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	.. and it's a terrible lubricant too for anything more than getting a stuck fastener turning. For a permanent application, you should use something made for the spot you're putting it on. :-)

09 October 2018, 13:33	#8
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	I don't think the shield is aluminium, it wouldn't have rusted if it was. I think it's just thin, possibly tin-plated steel.

09 October 2018, 17:55	#9
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,771	It might just be poor quality aluminium. Stainless steel isnt meant to rust either, but I have seen shit quality (otherwise known as Chinese) stainless steel rust countless times.

09 October 2018, 18:01	#10
nexus Registered User Join Date: Aug 2017 Location: USA Posts: 728	chinessium* WD stands for water displacement PB Blaster is another old school

09 October 2018, 19:35	#13
project23 Used Register Join Date: Jul 2018 Location: Liverpool Age: 41 Posts: 437	Yeah I don't know why i thought of alu, when it rusts so badly. If its just steel, try a bit of coke (as in cola) on a scrubbing sponge. Works wonders for old car fenders (but might not be enough for this)

09 October 2018, 20:08	#14
nexus Registered User Join Date: Aug 2017 Location: USA Posts: 728	vid above shows coke sucks at rust good enough when in a jam to get batt corrosion in your car terminals though

10 October 2018, 12:26	#15
ElectroBlaster Junior Member Join Date: Mar 2002 Location: Exeter, Devon, UK Age: 49 Posts: 1,705	These sheilds are somekind of thin tinned steel designed to resist corrosion, hence why they turn that scabby black! If rust becomes too much, it takes over and everything starts rotting. I cleaned up an A1200 shield by going in the hard way and using wet-n-dry sandpaper, water and wire wool. It will never look perfect but I managed to get the back row (port area) looking very nice! The best way is to get the sheilding stripped and re-coated. Somebody on the Amiga facebook group has been doing this and the results are 100%, almost like stock. Reminds me of when an Amiga was brand new almost

10 October 2018, 12:49	#16
project23 Used Register Join Date: Jul 2018 Location: Liverpool Age: 41 Posts: 437	Do you have a link for this at all? Is the strip and recoat process both electrolysis, coz I still have a setup in the shed I might play with hahaha.

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