Kenwood KAC-7204 Service Manual page 3

Ref. No. Application / Function
Q201~204 Differential fi rst stage amplifi er
Q205~208 Differential second stage amplifi er
Q209,210 Differential second stage current mirror
Q211,213 Temperature compensation Tr
Q215~218 Current limiter
Q220,222~227,229 Power amplifi er fi nal Tr
Q241,242 mute_Tr
Q251~258 Power amplifi er driver
Q281,282 ATT2_Tr
Q283,284 ATT1_Tr
Q602 Mute control
Q603,698 Power supply for the mute_Tr
Q604 SW14V
Q605 Pcon control
Q606 Over voltage detection
Q609 Power supply for FAN
Q610 Over current protection
Q611,612 DC protection
Q613,614 Latch circuit for DC protection
Q615,616 Shock noise prevention circuit
Q617,618 Shock noise prevention circuit control
NO. ITEM ALIGNMENT POINT
IDLE VR5 (Lch)
1
CURRENT VR6 (Rch)
Rch 2.5mV
-
DC voltmeter
COMPONENTS DESCRIPTION
Mute_on when is ON
The signal level becomes -3dB when is ON
The signal level becomes -1.5dB when is ON
ON when is pcon_off
Power supply for DC/DC_IC
ON by pcon=H
Turn off Q605 when over voltage is detected
Hold the protection operation while the DC protection is being operational
ADJUSTMENT
METHOD
Connect a DC voltmeter between check land.
Lch: Q223_emitter ↔ W148
Rch: Q224_emitter ↔ W21
Lch
VR5
Rch
+
VR6
Q224
Q220
X09-876
Operation / Condition / Compatibility
ALIGN FOR
2.5mV
Q223 Q227
R245 +
W148
DC voltmeter
KAC-7204
NOTE
after 5minutes from power on
Lch 2.5mV
-
3