Elenco Logic Probe Kit Manuale Utente Scaricare il pdf (Pagina 10)

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CAUTION: Do not connect the alligator clips to any AC power source or to DC power source greater than

35VDC. Failure to comply to this warning may result in damage to this instrument.

TESTING YOUR DIGITAL PROBE

Checking out your Logic Probe for proper operation is

fairly easy. All that is needed is a 9V battery or other DC

power source (5-10V). Connect the red alligator clip to

the positive terminal of the battery and the black clip to

the negative terminal. Set the PULSE-MEM switch to the

PULSE position and the TTL-CMOS switch to the TTL

position. Touch the probe tip to the positive side of the

battery, the PULSE LED should blink once and the HIGH

LED should light up. Place the probe tip to the negative

terminal and the LOW LED should light up. To check the

operation of the memory switch, set the PULSE-MEM

switch to the MEM position and set the TTL-CMOS

switch to the TTL position. Now touch the probe tip to the

positive side of the battery. The PULSE LED should

come on and stay on until the switch is flipped back to the

pulse position. No LED’s should light up when the tip is

not touching anything (open circuit).

The logic probe should operate at the following logic

levels when the power supply voltage is precisely set to

5VDC.

DTL/TTL Position Logic 0 - under 0.8V + 0.1V

Logic 1 - above 2.3V + 0.25V

CMOS Position Logic 0 - under 1.5V + 0.2V

Logic 1 - above 3.5V + 0.35V

TROUBLESHOOTING CHART

Condition Possible Cause

No LED’s light up. Power cord

Check U1, C7, or D6.

HIGH LED or LOW LED never lights. Check U1.

Test LED by shorting pins 1, 2, or 14 to negative supply.

HIGH or LOW LED always on. Check U1, R9 to R15.

Pulse LED always on. Check Q3 - Q5, U1.

PULSE LED never flashes. Check LED 3, Q1 - Q4, D3, D4.

All LED’s flash. Noise on power line.

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Elenco Logic Probe Kit Manuale Utente Pagina 10