[1000mp] Maintenance and Repair of the Mark V FP-29 PSU

[Harold Mandel]

Dear Ed,

Keeping the power supply plugged in,
and keeping the plugged-in power supply continuously
energized does not charge the lithium battery, nor does it
relieve the lithium battery from its stationkeeping function
in the circuitry of the radio. The battery will wear out and
discharge no matter what measures you take save, even
removing it from the radio.

Keeping the power supply energized and connected
to the power lines subjects the connected circuitry to
events called Power Line Disturbances that are spikes
occuring when loads are switched in and out of service
on the power network. These loads, mostly inductive such as
HVAC motors, compressors, etcetera, cause a pulse
on the power line sometimes approaching thousands
of volts, albeit at fractions of milliseconds.

However, these pulses are of so short a duration as to 
not be clamped by ordinary protective devices such as 
MOV's, Varistors, Capacitors, Chokes and combinations
thereof making filter circuits.

These pulses, traveling through protective circuitry,
penetrate control circuitry and end up puncturing the
microscopic layers of transistor and integrated 
device junctions. Very often, no damage is observed as a
result of enduring PLD's, but over time the damage, similar
to human tissue being irradiated by particulate ionized
radiation, breaks down and errors begin to occur where the
control signal needs to occupy the damaged microscopic
area.

This is why it's important to unplug whatever you are
not using. The On/Off switch may not be the protection
you deserve, especially when lightning can travel nine
miles through open air and blast a tree away.  Most
PLD's are not lightning, but they still are damaging.

Hal Mandel
W4HBM