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PC Electronics Plus (Most Significant Bits)(1995).ISO
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elec8.cai
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1991-11-05
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15KB
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330 lines
@OPTIONS ESCAPE NOEDIT
@ESC SYSTEM
.SCREEN 0
.COLOR 15,0
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ INTRODUCTION ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
The following procedures can be used to identify the causes
of most electrical and electronic system malfunctions. No
review questions are included in this section.
The procedures apply to both circuits utilizing separate
wires/components and those mounted on Circuit Boards. In
the case of Circuit Boards, use extreme care with VOM
probes to avoid touching two components or wire traces at
once (A condition that will create a "Short Circuit"). Also
note that most boards will have a clearly marked Ground where
the - probe of the VOM can be positioned.
Testing of integrated circuits, transformers, and other
products that utilize separate circuits is normally
limited to verifying input and output voltages.
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
.SKIP 6
┌──────────────────────────────────────────────────────────┐
│ WARNING │
│ │
│ELECTRICAL COMPONENTS CAN CAUSE SHOCKS AND ELECTRICAL │
│ │
│BURNS IF APPROPRIATE SAFETY PROCEDURES ARE NOT FOLLOWED. │
│ │
│USE EXTREME CARE TO AVOID THE RISK OF INJURY WHEN WORKING │
│ │
│WITH ANY SYSTEM THAT USES ELECTRICAL POWER. │
└──────────────────────────────────────────────────────────┘
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
When an electrical or electronic system fails to operate, the
problem will fall into one of four general categories:
1. LOW VOLTAGE/NO POWER AT SOURCE
2. MALFUNCTION IN DEVICE THAT USES POWER
3. BLOWN FUSE/OPEN SWITCH/MALFUNCTIONING COMPONENT IN CIRCUIT
4. BREAK IN WIRING/BLOWN FUSE/POOR CONNECTIONS
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
The troubleshooting procedure involves tracing the circuit
to identify the location of the problem.
Although a Test Light can be used to verify that there is
power in an electrical circuit, a VOLT/OHM Meter (VOM) is
required to verify that the power level is correct and to
perform more sophisticated troubleshooting operations. A
wiring diagram may also be needed to trace the circuit.
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
┌───────────────────────────────────────┐
│1. VERIFY THE POWER LEVEL AT THE SOURCE│
└───────────────────────────────────────┘
Modern automotive systems use a 12 volt
electrical system and all components
are designed to operate using 12 volts
of incoming power.
- more -
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
A. With the engine and all power using
components turned off take a voltage
reading with VOM to verify that there
is 12 volts at the battery.
B. Turn on the engine and all power using
systems (including the lights) and
recheck the voltage level at the
battery to verify that the voltage
level is correct under maximum load
conditions.
(Touch + probe of VOM to + battery terminal and - probe to - terminal)
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
.SKIP 5
NOTE: Voltage readings at the Battery are normally 12-14
volts. Although many components will function at levels
as low as 9 volts, erratic performance may result if the
voltage is less than the 12 volts specified.
A failure to obtain a 12 volt reading at the battery may
be due to a faulty Battery or malfunctioning charging
system (Alternator/Voltage Regulator). If twelve volts
cannot be obtained with all power using components in
operation, the Alternator may not have sufficient
output to meet the power requirements.
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────┐
│2. VERIFY THAT THERE IS 12 VOLTS AT THE POWER USING COMPONENT│
└─────────────────────────────────────────────────────────────┘
A. Identify the wire that links the + terminal of battery to
component that uses the power.
(NOTE: The wire is normally routed from the fuse box.
Aftermarket components may tap into the fuse box, tap
into a wire from the fuse box, or use a wire that is
connected to the battery. Most wires will be color
coded. If two wires lead into the component, the -
wire (ground) will normally be Black.)
- more -
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
B. Take voltage a voltage reading with a VOM to verify
that there is 12 volts of power in the + wire.
(In most cases there will be a plug-in connector in the
wires at or on the component. Detach the connector and
take the reading at that point.)
(Touch + probe of VOM to + wire being tested and - probe to ground)
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
NOTE: If the voltage reading at the component is correct
and the component does not function, the component is
the cause of the malfunction and should be repaired or
replaced.*
In the case of components that include circuits and
other components (radios, computer modules, etc) further
testing that may require specialized diagnostic equipment
is required to confirm that the nature of the malfunction.
* NOTE: Always to check that a poor ground connection
is not the problem (ground wire should be securely
attached to the body or component secured to body)
before concluding that the component is at fault.
Also, check component for any internal blown
fuses.
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
If there is no power in the wire leading to the component:
┌────────────────────────────────────────────────────────────────────────┐
│3. CHECK FOR BLOWN FUSES/OPEN SWITCHES/MALFUNCTIONING IN-LINE COMPONENTS│
└────────────────────────────────────────────────────────────────────────┘
A. Check for blown Fuses. The Fuse location for factory
installed components will normally be the vehicle's
Fuse Box. Aftermarket components are likely to include
in in-line fuse in the + power wire.
NOTE: If a Fuse is blown attempt to verify the cause
and correct the problem before replacing the Fuse.
Always replace a blown Fuse with one that has the same
voltage and amperage rating. Many times the cause will
be in the component that uses the power.
- more -
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
B. Check any in-line Switches. Newer vehicles with complex
electrical systems may include in-line Switches that will
only allow the component to function if certain conditions
are met (Air conditioners, instance, may include high and
low pressure Safety Switches). In vehicles with computer
controls, the computer may control an in-line relay.
NOTE: To check a Switch, use a VOM to verify that there is
power at the Switch. There should also be power in the wire
from the Switch when the Switch is "closed". To confirm a
Switch failure, use a "jumper wire" to temporarily bypass the
switch. If the component functions, the Switch has failed.
In the case of computer controlled relays, verify that there
is output voltage from the computer. If there is no voltage,
the computer may have identified a condition and will not
allow the component to function until the condition is
corrected, or the cause could be a computer malfunction. If
there is power at the relay but the relay does not "close",
the relay has malfunctioned.
- more -
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
C. Check any other in-line components including Resistors
and Diodes. There should be power on both sides of any
Resistor but a power "drop" equivalent to the rating
of the resistor. There should equal power levels on
both sides of a Diode. In the case of any Transistors
used, it is necessary to identify the function of each
of the three "leads" to determine where power readings
should be observed when the component is functioning
properly. In the case of a Transistor, also note that
when one is used as a switch there will be a "trigger
voltage" at which the switch will "close". If the
voltage reading is too low, the switch will remain
"open" and the circuit will not be completed.
NOTE: Do not use a "jumper wire" to bypass any in-line
Resistors of Diodes. Damage to other components in
the circuit may result.
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
If you do not obtain the correct voltage reading in
the wiring leading to the component:
┌──────────────────────────────────────────────────────────────┐
│4. TRACE THE CIRCUIT TO IDENTIFY BROKEN WIRES/POOR CONNECTIONS│
└──────────────────────────────────────────────────────────────┘
A. Perform a visual inspection from the component back
to the power source. If there is no power, check for
a blown fuse first. Then look for broken wires, loose
connections, and corrosion at connections.
- more -
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
┌────────────────────────────────────────────────────────────────────────────┐
│ ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ TROUBLESHOOTING ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ │
└────────────────────────────────────────────────────────────────────────────┘
B. Take voltage readings at the connections in the circuit
to aid in isolating the location of any problem. Any
points beyond the last location to show a correct
reading should be suspected.
C. If necessary disconnect any suspected wires at both ends
and test with OHM METER portion of VOM to verify that
there is a break in the wire (Any wire will show some
resistance. In a broken wire, the resistance will be
infinite).
.LOCATE 25,19
.PAUSE (*(Press ENTER to continue/ESCAPE to exit)*)
.CLS
@GOBACK :BEGIN
