wa8yxm wrote:
1978 likely has a very poor converter and a dead house battery
The wiring is fairly simple and in fact there are only two "Basic" diagrams
120vac---Converter--Common spot like the fuse block---Isolator relay/device---Cut off switch---battery.
And a 2nd one where the converter/charger is between the fuse block and the rest of the above. All lights and such connect to the fuse block
Now comes the fun part.. IF the fuse panel door says something like Magnetek 6300 that's your problem. Otherwise you need to start power tracing.. To do this I suggest 3 things
one is a "Smart" battery charger (you might also need a dumb one) to make sure the house battery is charged.. You may need a new one (or two)
Now the tools.. a spool of wire. say 18 or 20 ga 25-50 feet. and a pair of "Alligator" clips one on each end of the wire... A good trick is to unroll the wire and find the center.. Rewind both halves at the same time on the spool.
An anautomotive test light. This looks like an old fashion ice pick plastic handle is clear or translucent.. Bulb inside and a wire with a clip comes out of the handle.
Start at the battery. Clip to negative tip to positive bright light = good if not re-seat the bulb and try again. (NOTE battery must be charged)
Now transfer the clip to any unpainted metal part (Frame) still bright GOOD not bright you have a problem on the ground lead.
Now move out... Along the positive wires.. Find where they go still bright at the other end of the wire.. Good Still bright at the other end of whatever that wire is hooked to.. Good. Problem exists between bright and dark
What about that spool of wire? Have problem finding a good ground point.. Use the spool and hook one clip to the test light clip. the other to the battery negative.
This is my most useful 12 volt diagnostic tool
Checking an entire 30 fuse panel (modern blade fuses)
Find a good ground or use the extension
Touch each end of the fuse (The little windows in the fuse)
Bright bright = good
Dark dark = Switched circuit no test
Dark bright or Bright dark = Blown.
You don't even need to pull the fuse to test it
(Works with the 3AG style cartridge fuses too)
Thanks. It has an old fuse panel just behind the tongue. The fuses look more like small relays. There are no little windows like in blade fuses or even glass fuses. I do have a test light and a fancy circuit tester.
