Adjustment Procedure - Panasonic EB-G450 Technical Manual

The charging circuit is controlled by the current drawn by the handheld unit. If the handheld unit receives a call and

thus requires greater than 300mA, then it switches the charger off, only switching it back on again when the current

drops below 200mA. These current levels are controlled by VR3 (set the stop point) and VR4 (set the start point).

The power out for the handheld unit is protected by Q11, Q16, and Q5. When the power is connected, a small

current can flow through R27 and the bleed resistor R33. Through the potential divider R39 and R38, this turns Q5

ON, turning Q16 ON. Should the output CN2 become accidentally short-circuited the base of Q5 becomes low

turning Q5 OFF. This pulls the base of Q16 high, turning Q16 OFF and shutting off the power.

If any of the main components in the charger are replaced then the following procedure must be followed. The

procedure first adjusts the charge rate timer for each battery, followed by the control current levels for switching the

charger on and off.

Connect the charger as shown in the following diagram.

GND

Figure 1: Charger Connections

Adjust VR2 until the pulses on pin 3 of IC 2 have a period of 10mS +/- 0.5mS. Open the switch S1 and adjust VR1

until the pulses have a period of 3.45mS +/- 1.5mS.

With S1 closed connect a load of 300mA +/- 5mA across the output that goes to the handheld unit. Adjust VR3 so

that clock pulses on pin 3 of IC 2 stop i.e. there is a steady level of 5V or 0V. Now reduce the load to 200mA +/-

5mA and adjust VR4 so that the pulses start again.

MCUK971001G8

Technical Guide

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S1

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10K

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30 3W

Section 10

10 - 5

ACCESSORIES

10mS

500-1001

Revision 0

Issue 1