Amiga.org

Amiga computer related discussion => Amiga Software Issues and Discussion => Topic started by: Super TWiT on March 20, 2011, 09:01:25 PM

Title: Leaking Capacitors Corrode Board?
Post by: Super TWiT on March 20, 2011, 09:01:25 PM
I am pretty sure my A500 has flaky capacitors, since it is making noise during serial transfers.  I know I talked about this in another thread, but I have a question.  I checked the board for leaking capacitors really well, but didn't see any.  Are the capacitors more likely to just dry up inside, or will they leak?  I don't really care if the amiga makes noise, but if the capacitors are likely to leak, then I don't want them to ruin the board with corrosive liquid.  How likely is it that the dodgy capacitor would leak and corrode the board?
Title: Re: Leaking Capacitors Corrode Board?
Post by: Zac67 on March 20, 2011, 09:17:37 PM
Electrolytic caps dry up eventually. When there's enough load (=current) on them at the end of their life the last bit of electrolyte gets rather hot and is vented through the top or - more often - through the bottom rubber plug. With very little load they usually just dry up and cease life peacefully.

However, if these dried caps are not replaced they may cause collateral damage by not filtering out voltage spikes or not stopping other components from oscillating.
Title: Re: Leaking Capacitors Corrode Board?
Post by: Super TWiT on March 20, 2011, 09:27:25 PM
Yeah, I've got to get better at soldering so that I feel comfortable re-capping these things.  How likely is damage to occur?  Should I pay someone to do it?
Title: Re: Leaking Capacitors Corrode Board?
Post by: Damion on March 21, 2011, 12:19:58 AM
FWIW, I haven't seen one yet with leaky thru-hole capacitors that damaged the motherboard. The SMD ones are another story, in some cases pads and traces are destroyed.

If you're worried, clean the board around the capacitor areas with vinegar or IPA until you can get it repaired.
Title: Re: Leaking Capacitors Corrode Board?
Post by: orange on March 21, 2011, 12:39:37 AM
Quote from: Damion;623364
FWIW, I haven't seen one yet with leaky thru-hole capacitors that damaged the motherboard. The SMD ones are another story, in some cases pads and traces are destroyed.

If you're worried, clean the board around the capacitor areas with vinegar or IPA until you can get it repaired.


on A4000, audio caps usually leak. there is some problem with polarization there.
Title: Re: Leaking Capacitors Corrode Board?
Post by: kimsin on July 24, 2013, 05:33:20 PM
Caps usually dry up instead of leaking. Soldering thru-hole caps are quite easy it’s the surface mount caps with package sizes of 0201 that throws me off. If you feel that something weird is happening, just take a closer look at the PCB to confirm. @orange: Thanks for the heads-up. I didn't know that audio caps leak electrolyte.

prototype pcb assembly services (http://www.7pcbassembly.com/prototype-PCB-assembly.php)
Title: Re: Leaking Capacitors Corrode Board?
Post by: spirantho on July 24, 2013, 07:06:44 PM
It's not just audio caps - they all leak or dry up on the A4000. Even some of the ceramic ones do!
Title: Re: Leaking Capacitors Corrode Board?
Post by: mikrucio on July 24, 2013, 10:35:26 PM
i dont think the 500's had this problem, they used slightly higher quality components.
My 500 has all the original caps. still look good to me, machine working perfectly.
But then again... this is only like 4 caps in there.

prob worth changing them..
Title: Re: Leaking Capacitors Corrode Board?
Post by: magnetic on July 25, 2013, 04:30:56 AM
I just had my nTSC a600 repaired because the caps leaked and destroyed alot of traces...