Technics SE-A50 - Block Diagram; Measurements and Adjustments

@ BLOCK DIAGRAM
VOLTAGE CONTROL AMP
af
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5 > 7
&
weed a4ai
aS.
NFB
401,405
PRE DRIVE aN
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SE-A50 SE-A50
Q409
CURRENT CONTROL AMP Q553
C8) C8) Drive
4 8 ome.
re
Q557,559
Output
amp
amp
AA class
brige
network
Q415,419
ees a Q555 Q561,563
AA class
amp amp
Q4il
Q407
Current
stabilizer
stereo
ee himono t W\—-0-
| (C402:
|
$201 VOLTAGE CONTROL AMP
(STEREO/MONO)
| 4 8
LL Reh ¢ stereo F re =—A
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|
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|
i
|
|
SPEAKERS
—~ REMOTE
O
mieaes |
- 4p
Dill
(REMOTE )
i]
J-K FLIP-FLOP
(SPEAKER SELECT)
MUTING / PROTECTION
SIOl
(REMOTE)
n
—oO oO >
D609,611,613,615
RECT TI(Lch) S|
--=-7 Fy) (POWER)
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(| AC IN
DGEIO,612,614,616
D617~6 20
RECT easel
@ MEASUREMENTS AND ADJUSTMENTS
Control positions and equipment used.
@ Main speaker selector
@ Remote speaker selector
VOLTAGE CONTROL(V)AMP.IDLING(ICQ) ADJUST-
MENT
1.Test equipment connection is shown in figure. (Connect
the DC EVM on both channels.)
2.Completely turn the (V) amp. adjusting volumes (VR401
, ¥R402) counter-clockwise.
3.Turn ON the set when it is cold, and immediately adjust
VR401 and VR402 so that the voitage is 25mV.
Also, check that the voltage is 25 ~ 30mV (standard:
27mV) after lapse of 10 ~ 15 minutes. (Below 30mV af-
ter lapse of 20 min.)
CURRENT DRIVE(C)AMP.IDLING(ICQ)ADJUSTMENT
1.Test equipment connection is shown in figure. (Connect
the DC EVM on both channels.)
2.Completely turn the (C) amp. adjusting volumes (VR551
, VR552) counter-clockwise.
3.Turn ON the set when it is cold, and after the adjustment
of the (V) amp. ICQ, adjust VR551 and VR552 so that the
voltage is 3mV.
Also, check that the voltage is 4 ~ 7mV (standard:
5mV) after lapse of 10 ~ 15 minutes. (Below 10mV after
lapse of 20 min.)
eADJUSTMENT POINTS
@ DC electronic voltmeter(EVM)
OC EVM
ae
Lech. Reh.
Unit
TPA=TP401, TPB=TP402
TPA=Z551, TPB=Z552
eTest point
TP401 .... Loch Voltage control amp
Ica adj.
TP402 .... Roh Voltage control amp
Ica adj.
Z551_~«.... Loch Current drive amp
Ica adj.
Z552 ~«.... Reh Current drive amp
Ica adj.
eAdjustment VR
VR401.... Lech Voltage control amp
Ica adj.
VR402.... Roch Voltage control amp
Ica adj.
VR551..... Loch Current drive amp
Ica adj.
VR552.... Roh Current drive amp
Ica adj.