Pioneer hfe pioneer protection circuits troubleshoot free download

File name hfe_pioneer_protection_circuits_troubleshoot.pdf

TECI|NICAL OUIDE TOR SERI|ICE TROUBLE SHOOTING PROTECTION CIRCUITS I I I 1 t I PIONEEFI' SERVICE DEPARTMENT INTERNATIONAL DIVISION TROUBLE SHOOTING METHODS FOR PROTECTION CIRCUIT r'I()NEEFI' SERVICE DEPARTMENT INTERNATIONAL DIVISION 3. THE MAIN PURPOSE OF HAVING PROTECTION CIRCUITS IN AUDIO EOUIPMENT IS TO PROTECT THE POWER TRANSISTORS IN THE MAIN AMPLIFIER. HOWEVER, IN THE CASE OF OUTPUT CAPACITOR LESS (O.C.L.) MAIN AMPLIFIER CIRCUITS, LOUDSPEAKERS ARE DIRECTLY COUPLED TO THE AMPLIFIER. FOR THIS REASON WE MUST ALSO PROTECT THE SPEAKERS. +84tV Ra Rn Rr Cn Qa OCL }4AIN AMP CIRCT'IT 4. IN ORDER TO MEET THESE REOUIREMENTS, WE DESIGNED A CIRCUIT THAT WOULD DETECT A DEFECTIVE MAIN AMPLIFIER BY SENSING IF THERE IS A D.C. VOLTAGE PRESENT AT THE SPEAKER TERMINALS. THIS ALSO SENSES EXCESSIVE CURRENT IN THE OUTPUT STAGE. (5 THROUGH 9 NOT USED) PROIECTION CIRCUIT fl"tcTR0il MAIN AMP CIRCUIT CIRCU IT ( SPEATT POWER SUPPLY CIRCUIT 5. IN PIONEER O.C.L. MAIN AMP'S A "CUT OFF LOAD SYSTEM" IS EMPLOYED. THIS IS AN ELECTRIC SENSING CIRCUIT AND RELAY WHICH DISCONNECTS THE SPEAKERS FROM THE AMP WHENEVER THE AMPLIFIER OR SPEAKER MAY BE DEFECTIVE. THE PROTECTION CIRCUIT OF THIS TYPE WORKS EFFECTIVELY ON OCL MAIN AMPLIFIER AND, AT THE SAME TIME. THE ACTION IS VERY STABILIZED. 6. IN THESE NEXT SLIDES WE WILL LEARN HOW THE PROTECTION CIRCUITS OPERATE. AS AN EXAMPLE WE WILL USE THE PROTECTION UNIT FROM A SA-1OOO AMPLIFIER. DETECTIVE SECTION RELAY DRIVE SECTION Rr Cr R3 Rz Cz R4 7. THE PROTECTION UNIT IS COMPOSED OF THREE DIFFERENT CIRCUITS DESIGNED TO DETECT ANY ABNORMAL OPERATION IN THE AMP. LIFIER, SUCH AS EXCESSIVE CURRENT OR D.C. VOLTAGE ATSPEAKER TERMINALS. THERE IS ALSO A SECTION TO DRIVE THE PROTECTION RELAY. SPEAKER 8. WE CAN DIVIDE THE PROTECTION UNIT INTO THREE SECTIONS, CONSISTING OF TRANSISTORS O-1 AND O.2, O-3 AND O.4 AND 0-5,0.6, o-7.