Sherwood RD-7502 Service Manual page 21

Symptom
Digi-Link Failure.
Remote Controller Failure.
FM Failure.
AM Failure.
Stereo Effect Failure.
Stereo does not light up.
Tuner Sound Dead.
1. "L / R" Channel dead.
2. "LEFT" Channel dead.
3. "RIGHT" Channel dead.
Cause and Remedy
A) Digi-link line disconnection check.
Digi-Link IN/OUT circuit check.
B) Micom Interface Port Check.
1. µ-COM I.C B+( 3.3 )V check.
2 . Digi-link data I/O data check.
A) Battery check.
B) RMC I.C & Resonator inferior.
1. µ-COM I.C B+( 3.3 )V check.
2. REMOCON data check.
A) FM MUTE adjustment inferior.
B) FRONT-END inferior.
C) FM DET COIL inferior.
D) PLL&MPX IC check.
1. PLL&MPX I.C B+( 5 )V,B+( 3.3 )V check.
2. PLL control data check. (Data/CE/Clock)
E) TUNER B+ voltage inferior.
F) µ-COM I.C & Resonator inferior.
1. µ-COM I.C B+( 3.3 )V check.
2. Micom control data check.
A) AM V.T voltage inferior.
B) PLL&MPX IC check.
1. PLL&MPX I.C B+( 5 )V,B+( 3.3 )V check.
2. PLL control data check (Data/CE/Clock)
C) TUNER B+ voltage inferior.
D) AM OSC COIL inferior.
E) µ-COM I.C & Resonator inferior.
1. µ-COM I.C B+( 3.3)V check.
2. Micom control data check.
A) FM DET COIL Inferior.
B) PLL&MPX IC check.
1. PLL&MPX I.C B+( 5 )V,B+( 3.3 )V check.
2. MPX control data check.
C) STEREO adjustment inferior.
D) FM MUTE adjustment inferior.
E) µ-COM I.C & Resonator inferior.
1. µ-COM IC B+( 3.3)V check
2. Micom control data check.
A) MUTE TR inferior.
B) Connector's disconnection or disjunction.
Change or Close insertion of the connector.
C) FM DET COIL inferior.
D) AM IFT COIL inferior.
E) PLL&MPX IC check.
1. Signal IN/OUT terminal.
2. I.C driving voltage check. ( +5V,+3V3 )
20
Ref No.
R ( 485,437 ), D ( 513 ),C (451)
I.C NO. (402 ) / I.C Pin No. ( 9 )
I.C NO. (402) / I.C Pin No. ( 64)
I.C NO. (1 ) / I.C Pin No. ( 8,21 )
I.C No. ( 402 )
I.C Pin No. ( 53,54,55,58)
I.C NO. (1 ) / I.C Pin No. ( 8,21 )
I.C No. ( 402 )
I.C Pin No. ( 53,54,55,56,58)
I.C No. ( 402 )
I.C Pin No. ( 53,54,55,56,58)
I.C NO. (1 ) / I.C Pin No. ( 8,21 )