Testing Circuits

Testing Circuits

Circuit 1









Build this circuit per Wiring diagram. Use one bulb initially, second bulb will be added.

Do not turn on power supply until instructed.

Before applying power check voltage of power supply.

- Measure resistance of one bulb.
- Turn on power supply. Measure voltage drop across entire circuit.
- Measure voltage drop across bulb.
- Measure amperage of the circuit.
- Measure the resistance across a second bulb.
- Install the second bulb. Measure amperage of the circuit.
- How did the amperage change? Why?
- Measure the voltage drop across each bulb.
- Check voltage drop across top of fuse. (Third from right)
- Remove fuse and check voltage drop across fuse terminals.
- What type of circuit is this?

STOP DO NOT DISASSEMBLE CIRCUIT

Circuit 2









Build this circuit using the Wiring diagram.

Be sure the power is OFF

- What should the voltage be at points 1 and 2? (Do not measure)
- What should the voltage be at points 3 and 4? (Do not measure)
- Turn on the power supply. Measure voltage
at 1. 2.
- Measure voltage drop B 1.
- Measure voltage drop across both bulbs in each leg of circuit.
- Measure amperage in bulbs B1/B3.
- Estimate the total amperage of the circuit. How was the answer calculated?
- Measure total circuit amperage
- Remove bulb B4 from circuit.
- Measure amperage on circuit with only one bulb burning.
- What is the effect on the total circuit amperage.
- What type of circuit is this?

Circuit 3









Remove all light bulbs and jumpers leaving the power distribution box and switch.

Be sure power is off.

Build circuit per wiring diagram.

DO NOT APPLY POWER AT THIS TIME.

- Measure resistance of each resistor at resistor.
- Measure resistance between Pin 3 on Power Distribution Box (PDB) and Pin 2 on Resistor Pack (RP).
- Are the resistors wired in series or parallel?
- Turn on power, measure voltage at power supply.
Turn off power supply.
- Using Ohms' law, calculate the amperage of the circuit at RP Pin 3. RP Pin 2.
- Turn on power supply and switch. Measure the amperage at RP Pin 3. RP Pin 2
- With B- applied at RP Pin3 what is the voltage drop at RP Pin 3 and PDB?
RP Pin 2 and PDB?
- Move B- to RP Pin 2 and re-measure voltage drops.
- Turn off power supply.
Why did the voltage drops differ?

Circuit 4









Build circuit per wiring diagram.

- With power off, Switch in down position measure resistance between Pin 2 and Corn of slide switch.

Slide switch to up position, measure resistance between Pin 4 and Corn.

- Turn on power, put slide switch in up position.
- Measure supply voltage at PDB Pins 1/3.
- Measure voltage at Pin 86 of relay.
- Measure voltage drop between pins 86/85 of relay.(Switch in down position)
- Check voltage drop between pins 30/87 of relay
- Push down button on push button switch and hold. Recheck voltage drops on relay pins 86/85. 30/87.
What happened to the voltage drops?
- Move red jumper from Pin 2 of slide switch to Pin 1 of slide switch. Put switch in up position. Measure amperage of circuit. (Only two bulbs should be burning.) Push button on switch. (All lights should burn) Measure amperage.
- Continue pushing button, check voltage drop Pin 86 of relay to B- What happened?