| MODEL | RX-V800 / HTR-5280 | |
| TYPE | SYMPTOM/REPAIR | |
| SUBJECT | I-PROTECTION, BUT AMPLIFIERS ARE GOOD | |
| SYMPTOM: UNIT
IMMEDIATELY SHUTS OFF DUE TO OVER-CURRENT PROTECTION (I-PROTECT).
ALL AMPLIFIERS CHECK GOOD WITH NO EXCESSIVE LINE CURRENT MEASURED WHEN THE
POWER RELAY IS BYPASSED USING A VARIAC. THE COLLECTOR VOLTAGE AT Q35
MEASURES THE SAME DC VOLTAGE AS THE PRI TERMINAL TO THE
MICROPROCESSOR. (NO VOLTAGE DROP ACROSS R92 AND Q35 IS NOT TURNED
ON.) THE VOLTAGE ON PRI CAN BE BETWEEN 1V AND 4V.
CAUSE: THE MEMORY BACKUP CAPACITOR
(C633) HAS LEAKED ELECTROLYTE ONTO THE FUNCTION CIRCUIT BOARD CAUSING
VOLTAGE TO LEAK INTO THE PRI CIRCUIT. THE LEAKAGE MAY NOT BE VISIBLE
ON THE BOARD. SOLUTION: ONCE A TRUE OVER-CURRENT
PROTECTION IS RULED OUT, REMOVE C633 AND CLEAN THE CIRCUIT BOARD CAREFULLY
TO REMOVE ALL ELECTROLYTE RESIDUE. REPLACE C633 WITH A NEW
PART. CLEAR THE PROTECTION HISTORY USING STEP 9 (PRESET RESERVED) IN
THE DIAGNOSTIC MODE ON PAGE 19 OF THE SERVICE
MANUAL. | ||
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