Subject: YAMAHA TECH TIP
From: "Saved by Internet Explorer 11"
Date: Tue, 16 Jun 2015 22:06:51 -0700

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.

BY:
JGB

ENTERED:
03/07/03