Re: Electrolytic Capacitor Removal NO Desoldering Required


 

Hi Victor,

On Wed, Apr 22, 2020 at 02:36 AM, victor.silva wrote:


Louis is not repairing boards that have electrolyte leakage from capacitors.
I know. I was referring to the amazing improvement in copper trace bonding that has happened since the '70's when traces could easily be pushed away with a hot soldering iron.
The 2445/2465 families lie between the two extremes, timewise.

Most of the stuff he repairs is not even 6 years old.
I know, of course, see above.


My experience is mostly with the 2465B SM A5 assembly.
In many cases the pads are not even there anymore, the corrosion is so bad.
The twist method would only work on a 2465B SM A5 with no electrolyte damage,
which is very unusual.
Re. the twisting method, I was specifically referring to the TDS400/500/600 families, with many dozens of leaking caps each.
My most recent experience reconditioning a 2445/2465-family instrument (A5 caps, PS caps, mains filter caps, NVRAM/FRAM) is about 3 years ago.

My current instruments from that family are a 2465B, a 2467B and a 2467BHD. All have SMD-equipped A5's and none were so bad that pads were gone or even came off while working on them (yes, mostly using the twisting method). In fact, only the familiar matte solder surface gave away the leakage, no real corrosion visible.

I remember some other samples that were in much worse shape. I unsoldered some caps in those. Never lost a pad unless it was coming off already.


Only the very late >1993 A5s that were conformal coated
would show little damage.
My 3 units above certainly don't have conformal coating, if you're talking about a thick layer, covering the whole pcb. Never seen it on one of those instruments even. Nice!


I'm not going to be convinced to use the twist method. I've presented a method
that puts much less stress on the pads.
I doubt if perpendicular forces put less stress on the pads than forces almost purely in parallel with the pad/pcb interface.


I will let people decide to use what they want.
Thanks -;)

Raymond

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