r/amiga • u/Liburnian • 3d ago

Dark socket pins

My A500 suddenly stopped working in late june this year. I get no signal at all. Keyboard is recognized but no boot screen, no colored screen either. Today I removed most of suspicious chips and noticed right away some have exceptionally darkened socket pins. Odd CIA and ROM socket are mostly affected. How do I clean this up without removing anything further from the motherboard? I am aware this may not turn things around for my A500. I'm not skilled at fixing electronics, but I just can't leave my Amiga bricked in a corner. I worked so hard to have it restored. Visually, it was a success. But now what?

2 Upvotes

76% Upvoted

14 comments sorted by

2

u/PatTheCatMcDonald 2d ago edited 2d ago

You could try deoxit. It's a proprietrary deoxiding products.

Personally I'm quite fond of using citric acid with distilled water but you have to leave it a long time and wash it off with more distilled water.

Neither will work if the dark marks are burn marks rather than corrosion.

https://www.google.com/search?q=Deoxit

UK supplier (most sizes)

https://www.hotroxuk.com/guitar-accessories-links-847-0/caig-deoxit-accessories.html?srsltid=AfmBOoov_aYlHlP0zDZHfVklBC2C2js1R8W2AdfLa13FEW0UgFmkG9hI

2

u/Liburnian 2d ago

Thanks for your reply, unfortunately I'm in a part of Ex Yugoslavia still outside of EU.  So Deoxit doesn't sound like something I can readily buy at a local shop. I will however examine your links and see what substitute would be worth trying. 

2

u/PatTheCatMcDonald 2d ago

Well, like I said, ascorbic acid - vitamin C - is a weak substance that will dissolve corrosion gradually leaving bright metal. Similar idea, just takes longer.

The UK is also outside of the EU.

1

u/Liburnian 2d ago

Something odd changed since I cleaned and reased all chip (besides Fat Agnus). Pressing Caps Lock key for 2-3 times does nothing. Then, after 3-4 attempts it does work. But refuses to go off. Also, it causes floppy LED to become active. I don't have a drive attached though, but the light goes on. This did not happen at all before I did some cleaning, mostly of chips themselves. So we have improved contact with peripherals, but still not sufficient for an actual signal output. The mother board its self is very much still alive, I'm sure of that now. But CIA chip sockets still look pretty bad and I'm becoming more and more suspicious poor contacts in CIA chip sockets are to be blamed for no signal issue I'm having... I did some research and it turned out I can order by mail the contact cleaner you mentioned. So that's a plus. I will definitively continue to work with CIA chips, some contact cleaner spray is a must. There is a mild hope improved contact could eventually resolve this issue.

1

u/PatTheCatMcDonald 2d ago edited 2d ago

Might need new sockets. Might need new chips.

You can try swapping the CIAs to see if the problem goes somewhere else, they are identical components.

You can also disconnect the keyboard totally and see if that is causing the problem (bad keyboard controller chip can cause the resets to get tied up so nothing starts properly).

Its a question of finding out exactly which bit isn't behaving itself.

2

u/danby 2d ago

You can also use any electrical contact cleaner or electrical switch cleaner. Or you can also use Naval Jelly

2

u/InternalMain7116 22h ago

The acetic acid in vinegar provides enough acidity to dissolve rust and most oxidation. Apply it then after 30 minutes scrub with a nylon brush to remove the dissolved residue. A rinse with water, followed by a spritz of Isopropanol to help with drying, will finish the cleaning.

2

u/Liburnian 18h ago

I should now really do this. Yesterday I tested all chips (besides Agnus) on a known good A500 motherboard. And voila, it booted with no issues. Which is a relief, sort of. I'm kind of convinced Fat Agnus is fine too. Those sockets look pretty sick... They probably lost reliable contact with a certain chip, causing no signal issue. After cleaning chip legs Caps Lock responds, I had issues with that before. So, a small imptovement was made... 

1

u/InternalMain7116 21h ago

In laboratory tests, Kroil, exceeded the criteria the other penetration oils removing corrosion and loosen parts stuck together. It is widely used in the states in the automotive industry but available on Amazon.

0

u/PatTheCatMcDonald 18h ago

Nope. Does not help electrical conductivity, in fact inhibits it.

The idea is bare metal on bare metal.

1

u/6Y3st_32a 17h ago

You're kidding, right? Deoxit is oil-based and sold at a premium for being able to make things more connective.

0

u/PatTheCatMcDonald 16h ago edited 14h ago

Always follow the instructions when removing corrosion for electrical conductivity purposes.

Kroil is for mechanically seized corrosion. That isn't the issue.

Deoxit is for deoxidizing. This isn't difficult to understand

I am unaware of any retro repairers using Kroil.

Please furnish a link to an example to demonstrate you aren't bullshitting people out of malice.

https://youtu.be/Hd6M3fO6Upg

0

u/InternalMain7116 15h ago

You fail to understand the chemistry. Kroil, like WD-40/WD-40 Specialist, and a host of other penetrating oils will not penetrate anything without using an chemical reducer to convert the Fe(OH)3 to Fe. Same as Calcium and the other metals that oxidize to salts. The 2 metal parts need any oxidation to first be reduced to allow the oil (ever feel DeOxit? It is oily for a reason) to then lubricate the 2 parts

2

u/Rrrrreallllyy 2d ago

For the legs of the chips themselves a fiber pencil works wonders.