PDP 11 gear finally moved

Chuck Guzis cclist at sydex.com
Wed Jul 22 10:40:17 CDT 2015

On 07/22/2015 04:39 AM, tony duell wrote:

> Do you seriously replace both headlight bulbs when one fails? I know of
> nobody who does that. Generally you carry a spare bulb kit and a screwdriver
> and if a bulb fails, pull over and change it.
> Why not change all other bulbs on the car at the same time? Or change them
> all once a year as part of the service [1]? What about bulbs in your house?

Automotive bulbs (at least those used for external illumination and 
indication are used in pairs.  Most incandescent bulbs fail with age 
(manufacturing defects are an exception) and their light output 
decreases--the filament evaporates and darkens the envelope.  It's 
logical to anticipate that if an old lamp fails, its partner is not 
going to be long in following it. The effort to replace two bulbs is not 
much different than the effort involved in replacing one.

In my home,  if an old fluorescent tube in a multi-lamp fixture darkens 
and fails, I replace all lamps in the fixture.  This also applies to 
multi-bulb incandescent fixtures.  Again, balanced with the bother of 
hauling out a ladder and, in some cases, disassembling the fixture, it 
just makes sense.

Maybe I'm the only one who does this (and perhaps I'm the only one who 
coats incandescent lamp bases with a thin layer of dielectric grease), 
but it works for me.

Non-solid electrolytic capacitors do have a rated service life and so 
merit replacement after a certain age (depending on service conditions).


More information about the cctech mailing list