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Voltage analysis of power supply, Fuse replacement – Elenco Deluxe Digital / Analog Trainer with Tools Kit Version User Manual

Page 18

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VOLTAGE ANALYSIS OF POWER SUPPLY

Proceed with the voltage analysis only if the resistance readings were satisfactory.

Place the top panel on the unit. If any capacitors are inserted backwards, the panel will shield you if

they explode. Make sure that the ON/OFF switch is in the OFF position. Plug the line cord into the 120VAC

power source. Turn the unit on and let it sit for a few minutes. Turn OFF the ON/OFF switch and remove the

top panel, placing it along the left side of the trainer. Turn ON the ON/OFF switch and measure the voltage point

as listed in the chart below. The values given are approximate.

See Figure AA for locations of the testing points.

From

To

Circuit

Volts

Volts Measured

15

GND

+12V Regulator Input

+21V

B3

GND

+12V Regulator Output

+12V

16

GND

–12V Regulator Input

–21V

B2

GND

–12V Regulator Output

–12V

17

GND

+5V Regulator Input

+12.5V

B4

GND

+5V Regulator Output

+5V

18

GND

+20V Regulator Input

+28V

+20

5-pin connector

GND

Voltage ADJ +20V Regulator CCW 0V CW +20V

+20

5-pin connector

GND

+20V Output

CCW +1.25V CW +20V

19

GND

–20 Regulator Input

–28V

–20

5-pin connector

GND

Voltage ADJ -20V Regulator

CCW 0V CW –20V

–20

5-pin connector

GND

–20V Output

CCW –1.25V CW –20V

15VAC

15VAC

30VAC

30VAC

5-pin

5-pin

connector

connector

left

right

+30%

CCW - Counter-Clockwise CW - Clockwise

r

Turn unit off.

-17-

FUSE REPLACEMENT

1. Turn the trainer off and unplug it from 120VAC power source.
2. Unscrew fuse holder cap and remove fuse.
3. Use only a 1.25A fuse. Larger fuses or other fuse bypass will void the

warranty of the trainer.

4. Place the new fuse into the fuse holder cap and screw it back into the holder.

5. Plug trainer into 120VAC power source and turn the unit on.

Place the top panel on top of the unit.