April 2002
Electrical
Problems:
Well
I warned you on the front page that I’m not that bright and to prove it I have
recently burned up my radio and OAT gauge.
If you are interested in the details read on…
After
a x-country flight to Ottawa I noticed the alternator whine had returned in the
radio. While investigating this I
noticed a wire on the master switch was warm to the touch. The poles on the ALT side of the master
switch were blackened and loosened.
Since the switch is supposed to be a 20amp unit and the wire
terminations were still making good contact I am at a loss to explain how this
happened.
The
supplier of the regulator recommends a different wiring arrangement than I
originally used (see original schematic and suppliers diagram link below). The difference is that I ran the AC output
from the ALT through the master switch rather than directly into the regulator
as per the supplier. My original
reasoning was to allow for isolation of the regulator from the alternator.
Since
I could not explain the damage to the master switch I re-wired the alternator
output directly to the regulator as shown.
The output from the regulator is wired to the bus (not to the battery)
through a 20 amp CB and was not changed.
Can anyone see why this is heading straight to the radio repair shop
here?
Everything
works fine until the master switch is shut off in this arrangement. At that point the voltage regulator goes
postal by shooting up to 26 volts (one of those undocumented features) and
since we are no longer switched through the master this gets dumped straight to
the bus. Any electrics currently
on-line are dispatched straight to Valhalla.
Plan
B:
In
Plan B you see I have switched the DC output from the voltage regulator through
the master preventing a repeat occurrence of tranceivercide through switching
boo-boos. But if you look carefully at
the schematic you can see there are simple mechanical failures, which can
produce the same set of circumstances.
The most likely scenario involves the ammeter or master relay failing
which again drops the battery (but not the regulator) off the bus sending my
sociopathic voltage regulator on another killing spree.
Plan
C.
The
only safe way to set this thing up seems to be as shown in the original diagram
(with the addition of a CB between the regulator and battery). This means the ammeter will need to be
replaced by a voltmeter as shown in the new schematic.
All
of this is for naught of course should the regulator fail internally and go
into an over volt situation. It is
unlikely I will be able to spot the problem before I need Chuck at the VAL
repair centre again. Does anyone out
there know of a good (light/inexpensive) over voltage protection device?
Costs:
Radio
repairs – 125 USD
Gauge
repair - 28 USD
Shipping - around 100 CDN
The
realization that I am a moron - priceless.
Now
I can get down to finding the radio noise I started looking for in the first place
(and people wonder why I drink).
