Retinning edge contacts, or reconditioning?

[ChadTower]

So, which is the more effective?  A regular retin with solder, or using a product like this:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=64-4337

[NoOne=NBA=]

I've never found it necessary to do either.

Except in the most extreme cases, the original contacts shouldn't require more than a simple cleaning.

The only cases that I've ever personally run into that were even close have been Atari 2600 cartridges, after YEARS of insertion/removal.

I haven't personally found any of them that I haven't been able to clean with a typing eraser, and make to work again though.

[ChadTower]

It is VERY common in old arcade PCBs, especially Atari PCBs.  Simple age and hostile arcade environment causes the contacts to oxidize and voltages to go wonky, destroying transistors, fuses, etc.

[NoOne=NBA=]

Simple age and hostile arcade environment causes the contacts to oxidize and voltages to go wonky, destroying transistors, fuses, etc.

You don't need to retin oxidized contacts.
You just have to get the oxidation off of them.
A typing eraser will take care of this quite handily.

The retinning/paint is designed to rebuild WORN contacts, not dirty ones.
If you tin/paint over an already bad connection, you're just going to get a slightly better bad connection.


As an example, think of the battery contacts on a car.
If they are oxidized, and you replace your battery cables (without cleaning the battery posts) you are still going to get a bad connection because of the oxidation on the posts.
It might give you a good enough connection to start the car (where it wouldn't before), but you still don't have a good connection.

If oxidation was the only problem (as opposed to corrosion inside the cables) then cleaning the posts/cable ends, and reconnecting them, will give you as good a connection as replacing the cables, and cleaning the posts.
There wasn't anything wrong with the original connectors, other than the fact that they were dirty.
Once they are clean, they will operate at full efficiency.
Replacing them is unnecessary.

[ChadTower]

Talking about the Atari boards, IIRC, half the reason you do it is to increase surface connectivity between the old Atari edge harnesses and the edge contacts.

[NoOne=NBA=]

If you're trying to build them up to ensure good mechanical connection, I'd go with tinning.
It will add height, much easier than the conductive paint.
That will increase connection pressure, and may result in a larger area of contact.

That being said, you might be better off to just replace the edge connectors themselves, to achieve a tighter fit, and better mechanical connection.

[ChadTower]

That's part of the plan... not to replace the connectors, but to replace the pins in the connectors.

[SirPeale]

Don't forget to clean the connectors as well.

Tinning the edge is fine.  It's a good way to build up some bulk to make sure the edge can actually contact the pins.

The *best* thing to do would be to replace the connector.  Usually that's really difficult.  You could also flex each pin to have better contact with the PCB.