No specific LBC content. Our cars have blessed few of these.
Diodes and Electrolytic Capacitors are directional.
Resistors and most non-electrolytic Capacitors can be installed either way.
Now I am going to make mistakes that someone else can correct me on.
WARNING! This is only from my own experience (I am not an EE!).
Color coding and size sounds like a power resistor of a couple of watts,
especially if it's made of ceramic type material. (but take it to an expert).
Electronic components inside an OEM assembly are notoriously lacking in
markings and even standard components come in oddly marked or shaped packages.
Before I go trying to figure out what component has gone bad, I look carefully
at all of the solder pads and leads. Many times it's just a corroded or "cold"
(non-shiny) solder joint. Refloat (remelt) the offending connection and try
again. Power supply repair is usually a losing battle, the component that
burnt out sometimes is because another component is marginal.
Resistors: 4 color codes on lower power ones, sometimes ceramic for higher
power. Higher power ones are usually marked with the reading in ohms (or the
greek letter omega, and upside-down rounded U). Usually the leads are axial
(strait through the center of the resistor). Shown in schematics as -/\/\/\/-,
numbered on boards as R1, R2 etc.
Capacitors: Metal cans with two leads coming out axially or radially (both out
same side) or plastic blobs with the leads coming both out the same side.
Usually marked with a uf (microfarad) or pf (picofarad) rating as well as a
voltage rating. (both must match, sometimes you can get away with close
values). Electrolytic caps have one end marked + or the end of the can
crimped. Shown in schematics as -|:|:|:-, numbered on boards as C1, C2 etc.
Diodes: small ones are glass or plastic. One end marked with a white band.
Show in schematics with a triangle and bar symbol - |<-. If you measure the
resistance one way (+ one end, - on other, meter on ohms) will be almost 0, the
other way will be very large. Sorta like a one-way valve.
Transistors: Power transistors are usually flat plastic boxes with 3 leads and
bolted to a heat sink. Sometimes oval (gasket) shaped and made of all metal.
Smaller transistors have 3 leads and are about the diameter of a pencil with
one side flat. Marked on diagrams as 3 leads with a circle -()< and some
markings inside depending on the type of transistor. Leads only get hooked up
one way.
Chips: Small boxes with two rows of leads on 0.1" centers. Marked in diagrams
as they look. Marked with mfg and type on top of chip. Small round dimple near
pin 1. Pin 1 is usually power to the chip, opposite corner is ground.
P.S. Pulled apart my non-working Midget tach last night to find a TI chip
(M7445) and color coded capacitors that I could find NO documentation on, the
board itself had resistant traces. Finally just swapped the whole board for
one from an earlier style (but working) tach (74.5 B).
Christian Stanton
'78 Midget
'68 SAAB 96
'86 SAAB 900S
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