System Microcomputer Test Program; How To Check The Revolution Number Detection Circuit; Block Diagram - Pioneer DEH-P780MP Service Manual

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6.4 SYSTEM MICROCOMPUTER TEST PROGRAM

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- PCL Output
In the normal operation mode (with the detachable panel installed, the ACC switched ON, the standby mode
cancelled), shift the TESTIN IC601(Pin 126) terminal to H.
The clock signal is output from the PCL terminal IC601(Pin 62).
The frequency of the clock signal is 625.000 kHz that is one 32th of the fundamental frequency.
The clock signal should be 625.000 kHz(- 25 Hz, + 25 Hz).
If the clock signal is out of the range, the X'tal (X601) should be replaced with new one.

6.5 HOW TO CHECK THE REVOLUTION NUMBER DETECTION CIRCUIT

- Connection Diagram
Audio Oscillator
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L 13942296513
DC Regulated
Power Supply
- Checking the Revolution Number Detection Circuit
1. Input 400 mVp-p sine waves and confirm change of output voltage according to frequency.
2.There is a definite relation between alternating current frequency and the engine revolution number.
Frequency at 4 000 rpm can be set by user operation.
Linear complement between 0 rpm = 0 Hz and 4 000 rpm.

- Block Diagram

ACC Line
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