DC Fundamentals Unit 1 – Trainer Familiarization
Exercise 2 – F.A.C.E.T. Base Unit Familiarization ....................................................................
EXERCISE OBJECTIVE
When you have completed this exercise, you will discover the operating features of the base unit
and DC FUNDAMENTALS circuit board. You will verify your results with an operational test.
DISCUSSION
- The base unit contains CM and fault read relays, power supply controls, LEDs (light-emitting
diodes), and a ZIF connector that accepts circuit boards. - Power is applied to the base unit when the AC cord is plugged in and the power switch is on.
- The base unit's power switch should be in the off position when inserting circuit boards.
- On the base unit are LEDs indicating the presence of the plus and minus 15 Vdc internal
supplies. The LEDs are located above the control knobs of the negative and positive variable
supplies. - When power is applied to the base unit, the LEDs illuminate.
- One or both LEDs will be off should a base unit and protective circuit activate (to crowbar
the base unit's power source). - To remove the crowbar condition on a base unit, correct the problem, and turn the POWER
switch on. - Each of the internal variable power supplies are adjusted with COARSE and FINE knobs
(concentric shaft) located on either end of the base unit. - The left controls adjust the negative variable supply between 0 Vdc and -10 Vdc.
- The right controls adjust the positive variable supply between 0 Vdc and +10 Vdc.
- There are twenty computer-controlled CM read relays, numbered through 20, in the base
unit. - Initially, CMs are made inactive by the computer.
- When a CM is activated, a selected circuit located on the circuit board is modified.
- There are twelve computer-controlled fault read relays in the base unit.
- Initially, all faults are made inactive by the computer.
- Each fault, when activated, inserts a malfunction in a selected circuit located on the circuit
board.