SONY 910101 Service Manual

Service Technical Information

MODEL NO.

MINI-SYSTEMS AND RECEIVERS

SUBJECT:

TROUBLESHOOTING GUIDE FOR DEAD SET

START

Bulletin # 91-01-03

Date: May 17, 2001

IS 12VOLT VM

PRESENT?

Yes

IS -VFL

PRESENT?

Yes

IS VDD

PRESENT

TO CPU

Yes

IS CPU HOLD

INPUT 'HIGH'?

IS DC INPUT

PRESENT ON VM

REGULATOR?

Yes

12 VOLT

REGULATOR

DEFECTIVE

-VFL

REGULATOR

DEFECTIVE

VDD

REGULATOR

DEFECTIVE

WHEN THE HOLD INPUT TO THE CPU IS 'LOW',

THE POWER CANNOT BE TURNED ON. THIS

CONDITION USUALLY OCCURS WHEN ONE OF

MORE POWER AMPS ARE DEFECTIVE.

WINDINGS OPEN?

TRANSFORMER

ARE POWER

TRANSFORMER

Yes Yes

REPLACE

IS FUSE(S) OPEN?

REPLACE

FUSE(S)

ISOLATE THE

HOLD LINE FROM THE

AMPLIFIERS.

CHECK BRIDGE

RECTIFIER

Yes

CHECK

X'TAL

DOES POWER

COME ON?

ARE ALL AMPS ISOLATED? (SOME UNITS HAVE SURROUND CIRCUIT BOARDS THAT MAY BE

CAUSING THE TROUBLE).

Yes

CHECK AMPLIFIERS.

CONNECT DUMMY LOADS TO

THE SPEAKER TERMINALS AS

THERE MAY BE DC PRESENT

AT THE OUTPUTS.

THE HOLD PRINTED CIRCUIT PATH

MAY BE SHORTED TO GROUND OR THE

Yes

CPU MAY BE SHORTED INTERNALLY.