Re: Power supplies keep crapping out on me

["w_tom" <w_tom1@usa.net>]

  Few components in an Apple II power supply are custom.Inspection
rarely identifies a failed part.   Those power supplies should be
easily repaired - if not by you, then by most any TV repair shop.   I
would not even consider a computer repair shop since most repairmen
there only know how to fix things by shotgunning.  Replacing a soldered
part?  Too many would not even know where to begin.  Unlike new power
supplies, those Apple IIs use 'easy to obtain' and 'easy to replace'
parts.

  Damage from lightning is an electrical path from cloud to earth.  If
lightning enters a bullding, then current through electronics makes a
destructive connection to earth.  For example, the most common incoming
path is AC electric - maybe on black (hot) wire.  Path to earth is
through UPS.  UPS shunts (distributes, connects) that transient onto
other wires.  Now surge can find earth via Apple on black, white, or
green wire.  UPS simply provided such transients with more paths to
find earth.

  One path might be through Apple motherboard, through thermocouple(?)
electronics, through thermocouple, and to earth ground via fermenter.
If thermocouple electronics was both an incoming and outgoing path,
then that item would be destroyed.

  Demonstrated by example is how to locate other potentially damaged
electronics.

  Apparently you got lucky.  The transient was only large enough to
confuse - not damage - HVAC electronics.  It was a warning, this time.
Effective protection demands that each incoming utiltity wire make a
short connection to earth before wire enters the building.  Telephone
would already have a 'whole house' protector to connect each wire in
the phone cable to earth ground.  AC electric will not have such
protection unless you have installed a 'whole house' protector AND have
upgraded building earthing to post 1990 National Electrical Code
requirements.

  If no properly earthed 'whole house' protector, then lightning surges
may find earth ground via household electronics.  How often?
Llightning surges occur typically once every eight years.  For you,
that number will vary based upon geology, location, and neighborhood
history.

  Don't think for one minute that a UPS did anything other than battery
backup.  If in doubt, then read its numerical specifications.  Where do
they list each type of transient and claim that protection with
numbers?  Notice, no such claim.  Protection is about earthing a
transient before it can enter a building - long before it can overwhelm
protection that was even inside that Apple II.

Scott Alfter wrote:
> For the past couple of years, I've been running one of my spare Apple IIs
> 24/7 as a temperature controller.  ...  However, I've now had three power
> supplies fail on me.  It's used to switch the compressor of a refrigerator
> on/off, which I use to keep fermenting beer at the proper temperature.
> ...
>
> The most recent failure was sometime last week.  I briefly considered
> shutting the computer off during a particularly nasty storm that hit Las
> Vegas Monday evening.  A nearby lightning strike must've induced a surge in
> the cable to the temperature sensor, causing it to lock up and return
> invalid data.  (A similar surge must also have been induced into the HVAC
> wiring, where it zapped the settings in the thermostat.  It's worked
> properly since then, once I reprogrammed it.) Turning the computer off for a
> few seconds and turning it back on worked OK, but then I decided to just
> turn it off and leave it off.
> ...
>
> I have it on a UPS, so it should be protected from "power nasties."