[sdiy] Lifespan of Electrolytics?

[Cynthia Webster]

Thanks Grant, Jim, Eric, (and others) I just learned something here,
however I must say that I'd be mighty cautious in doing so...


Cynthia


on 5/20/02 4:34 PM, Grant Richter at grichter at asapnet.net wrote:

> 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
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>> 
>> 
>