[sdiy] Lifespan of Electrolytics?

[Grant Richter]

Have to second the motion on that. Also recap old test equipment.

Usually, electrolytics open up rather than short. This causes problems for
interstage coupling caps, as they disconnect the stages (and the sound).

Electrolytics are also commonly used for power supply filtering and
bypassing. In this case they are directly across the power supply rails. The
purpose of bringing the line voltage up slowly is to allow the electrolytic
to reform, without puncturing and causing a short.

A Variac is a variable autotransformer. They weigh a lot because of lots of
wire and metal cores. Because they are a purely passive magnetic device,
they do not distort the power waveform. You can safely use them to vary the
voltage into a transformer.

A so called "motor control" is usually a triac with variable phase
triggering. These produce sharp edges and radio hash, and could be bad for
your circuit. They weigh very little because of the solid state controls.
Dremel used to produce a tabletop model for controlling the moto-tools.

> From: "Paul Schreiber" <synth1 at airmail.net>
> Date: Mon, 20 May 2002 13:13:17 -0500
> To: "Joe Kramer" <musetrap at earthlink.net>, <synth-diy at dropmix.xs4all.nl>
> Subject: Re: [sdiy] Lifespan of Electrolytics?
> 
> About 18-20yrs TOPS for these caps. I *immediately* replace all these caps in
> my vintage synths.
> A great selection is found at www.digikey.com  as many older gears has axial
> caps. Philpis makes
> these "solid electrolyte" axials that are somewhat expensive (say $3ea) but
> last like 30 years.
> 
> Paul S.
> 
> ----- Original Message -----
> From: "Joe Kramer" <musetrap at earthlink.net>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Monday, May 20, 2002 1:08 PM
> Subject: [sdiy] Lifespan of Electrolytics?
> 
> 
>> Hi Folks,
>> I recently got ahold of a Tapco 4400 reverb for cheap because one channel
>> was dead.  After chasing down a handful of 4136s and systematically replacing
>> each one, I came to find that the actual problem was a bad electrolytic in
>> the
>> signal path.  The circuit board is dated 2/17/77.  I'm guessing that several
>> more of the caps in this board are marginal.  What is the expected lifespan
>> of
>> electrolytics, and what are the effects of old and aging ones?  Is it worth
>> the
>> trouble going through any old gear including synths that are past, say, about
>> twenty years and giving them a electrolytic overhaul?  Anyone have firsthand
>> (or secondhand) testimonials?  Thanks.
>> 
>> Regards,
>> Joe Kramer
>> 
>> 
>> 
>> 
>> 
>> 
> 
>