Circuit diagram for testing the switch
1 – resistor 0.01 Ohm±1%, not less than 20 W; 2 – switch; 3 – ignition coil; 4 - spark gap; A - to the oscilloscope; B – to the rectangular pulse generator
Pulse shape on the oscilloscope screen
A – voltage pulses (U) of the generator;
B – current pulses (I) of the switch;
t – current accumulation time;
T – pulse period;
Ti – pulse duration
A contactless ignition system can be equipped with a switch of type 3620.3734 or RT1903, or PZE4022. It converts the control pulses of the contactless sensor into current pulses in the primary winding of the ignition coil.
The switch is tested using an oscilloscope and a rectangular pulse generator according to the diagram in Fig. Switch testing diagram. The generator output resistance should be 100–500 Ohm. It is advisable to use a two-channel oscilloscope: the 1st channel is for generator pulses, and the 2nd is for switch pulses.
Rectangular pulses simulating sensor pulses are fed to terminals "3" and "6" of the switch. The pulse frequency is from 3.33 to 233 Hz, and the duty cycle is (ratio of the period to the pulse duration T/Ti), equals 3. The maximum voltage Umax is 10 V, and the minimum Umin is no more than 0.4 V (see oscillogram A in Fig. Pulse shape on the oscilloscope screen). For a serviceable switch, the shape of the current pulses should correspond to oscillogram B (see fig. Pulse shape on the oscilloscope screen).
For switch 3620.3734 at supply voltage of (13.5±0.5) V, the current value (I) should be 7.5–8.5 A. Current accumulation time (t) is not standardized.
(The original source is located on the website: VazBook.ru)
For the RT1903 switch, at the same supply voltage and frequency, the current is 7–8 A, and the accumulation time is 5.5–11.5 ms.
For the PZE4022 switch, at a supply voltage of (14±0.3) V and a frequency of 25 Hz, the current strength is 7–9 A, and the current accumulation time is not standardized.
If the shape of the commutator pulses is distorted, then there may be interruptions in spark formation or it may occur with a delay. The engine will overheat and not develop rated power.
Attention! Do not disconnect the plug connector from the switch when the ignition is on, as this may cause voltage of up to 400 V to occur in certain sections of the switch circuit and damage it.
Attention! It is not allowed to lay low-voltage wires in the same bundle with high-voltage wires.
Caution! Do not disconnect the wires from the battery terminals while the engine is running, as this may damage the switch.