[sdiy] Korg Delta problem

[Dave Brown]

There are bad years and suppliers for SMT electrolytics that do leak and corrode PCBs.  The corrosion takes out runs and vias.  We see this at the vintageTEK museum.  We refer to the incident as the “caps pee’d all over the PCB”.  At that point we consider them toast but I have seen people work to restore the PCB.  It is a lot of work.


Dave

 

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Pete Hartman
Sent: Monday, June 18, 2018 3:56 PM
To: synth-diy at synth-diy.org DIY
Subject: Re: [sdiy] Korg Delta problem

 

I literally had spew from an SMD electro corrode and damage the PCB on a Roland XP-50.

I had another synth where I couldn't get it to do anything until I replaced some mylar caps in the psu section.

So yeah, caps go bad.

Acknowledging that is NOT the same thing as "MUST RECAP EVERYTHING" shotgun "troublshooting".

 

Pete

 

 

On Mon, Jun 18, 2018 at 5:45 PM, <sleepy_dog at gmx.de> wrote:

Gordonjcp wrote:

On Mon, Jun 18, 2018 at 10:01:45PM +0200, Jean Bender wrote:

thanks !
you mean the caps from the power supply ? How could the power supply
only disturb or make no functionnal only half part from the synth ?

You'll never find "bad caps" in a synth.  They're pretty much a myth.

How so? Is it a myth that electrolytic caps will chemically degrade?
I have been told by more than one EE not to bother using electrolytics that have been laying around for 5 years, not just for things requiring low ESR, not for anything.

I don't have any numbers. But even in some simple old synth PSU with a pair of fat caps and linear regulation, it would be bad if those caps got a huge ESR and reduced capacitance, no? Now I can imagine that this is considered in the circiut designs, but only so much?




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