Re: Ten years after

[ddillon@renaissance.cray.com (David Dillon)]

On Thu, 01 Aug 1996 21:46:43, Ohad <guetta@netvision.net.il> wrote:

> I have been told that trying to operate a hammond that hav'nt 
> been used for some years may blow the condensers that got dry, 

Yes, the electrolytic capacitors (which were called "condensers" when
Hammonds were first built) can deteriorate in two common ways:

-- The moisture in the electrolyte can indeed evaporate, or dry out.
   A dried-out capacitor must be replaced; it can't be fixed.

-- The dielectric layer, formed by an electrochemical reaction during
   manufacturing, can de-form.  If full voltage is applied suddenly to a
   de-formed capacitor, the dielectric layer will be too thin and the
   capacitor may arc internally, short out, rupture and be ruined.

   A de-formed layer can be re-formed by slowly applying a limited
   current for several hours.  Best way to do this in an old Hammond:
   Disconnect the motors and apply AC power gradually through a Variac
   or similar adjustable transformer.

> and that during the years some wires may get broken.
> Is it right?

In a wire, the copper that actually conducts the electricity doesn't
often break, unless the wire is somehow stressed, strained or flexed.
This would be very uncommon inside a Hammond organ.

But it is common for the insulation on old wires to become brittle with
age, and to crack and fall off.  In the oldest Hammond organs, the first
wires that seem to have this problem are the most dangerous ones -- the
AC power input and distribution wires.  If the insulation falls off of
two wires run together, this could create a short circuit and a possible
severe fire hazard.

Strangely, Hammond's famous over-engineering did NOT include fuses.

--
Dave Dillon
San Jose, CA, USA