Servicing Personal Computers, 3rd Edition

91

Logic 1

(a)

Logic 1

(d)

Logic 1

(e)

(f)

(9)

Figure 2.16. Method of checking a J-K bistable using a logic probe and logic puiser

92 Servicing Personal Computers

however, no need to cut the PCB tracks if a current tracer is available. Such an instrument can

measure, to a reasonable approximation, the current flowing in standard size PCB tracks

without the need to break the circuit.

Two forms of current tracer are available; one operates by sensing the magnetic field in the

vicinity of the track and the other measures the voltage drop across