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Fixing / replacing eyelets

PostPosted: Tue Jul 26, 2016 11:16 am
by Text_Edifice
Hi all,

so I got a bit over-zealous with the desoldering gun and managed to pull an eyelet off a channel strip I'm trying to fix.

I followed the circuit and managed to get the component wired back in and connected to the right components with a bit of extra solder (continuity tests as per working strips) - but as the strip was exhibiting problems I don't know if this is going to bite me in the arse later.

Anyone got a hot tip for fixing this kind of stuffup? Is it something I need to worry about?

Re: Fixing / replacing eyelets

PostPosted: Tue Jul 26, 2016 11:53 am
by chrisp
Hi Dave

A picture might help us here, mate.

In broad terms, there is no electrical difference (as you have found) between a solder connection and an eyelet. The eyelet, though, provides a strong mechanical connection, both by anchoring the components to a position on the board and also a physical "wire wrap" connection for the component lead on top of the solder connection. A solder connection will not provide this mechanical strength to the same extent, so even though the electrical connection may be fine, the question is the mechanical sturdiness, which in turns sort of depends on the vibration, movement and bangs the unit will be required to bear.

I have also seen some old circuit boards where an eyelet seems to be used simply to raise a component higher off the board, either for space purposes or for heat management. A particular instance is the voltage dropping resistors in some tube circuits that act as little 2W bar radiators, and for these you don't want them snug to the board, you want good airflow all around them, so raising them higher is A Good Idea(tm).

So a few points to consider in the context of your circumstances.

Good luck with it

Re: Fixing / replacing eyelets

PostPosted: Tue Jul 26, 2016 11:59 am
by Text_Edifice
I'll be back with a pic - but it just looks like solder blob at the moment and I am cautious to desolder...

In this case it's a console group strip and the component is a cap. The cap still sits comfortably in the hole so I'm not too concerned with it moving about.

Guess I was wondering what the process might be if I was going to repair the eyelet?

Re: Fixing / replacing eyelets

PostPosted: Tue Jul 26, 2016 12:34 pm
by Gian
When this has happened to me, I make the component leg a bit longer (might need to replace the component) and ensure that the leg goes through the hole and then sits on the track for a few millimetres. And the leg is also soldered to the track.
For additional strength, if required, I also create a ring from the component leg and wrap that on the other side of the PCB around the leg (that has the missing eyelet) and solder that in place. That way there is mechanical strength on both sides of the pcb -- you dont want the component being pushed and lifting the track on the other side either, and this strategy mitigates that.

Re: Fixing / replacing eyelets

PostPosted: Tue Jul 26, 2016 1:04 pm
by Sammas
Do you mean the solder pad?

One over-the-top method of fixing them is to use solder braid (the stuff used for wicking up solder). Cut off your desired length then literally solder it along the damaged trace to tidily meet up with your new component and the damaged solder pad. The braid really sucks up solder though, so you really only need some very thin braid.

It is a bit heavy handed for busted pads in the audio path, or in low voltage circuits. Folding the leg of the component down along the trace works just as well... but I have found it very useful through mains powered circuits where a lifted pad can cause enough resistance and heat to start charring the circuit board.

Re: Fixing / replacing eyelets

PostPosted: Tue Jul 26, 2016 5:16 pm
by chrisp
I should have added that eyelets can also be an old school form of through-hole plating where traces or components are present on both sides of a PCB.

Replacing them is not that hard - eyelets and riveting tool readily sourced off ebay. See for the idea.