Panasonic Technics SA-800 User Manual

M@ POWER TRANSISTOR PROTECTION CIRCUITRY
When speaker terminals are shorted or an overload voltage is applied to the power
transistor, the emitter resistance voltage of the power transistor is applied to
terminals 2 and 3 and to terminals 13 and 14 of IC903. This voltage actuates the
switching circuitry of |C903, and positive voltage from terminal 4 turns on TR909.
When this happens, the TR909 collector
becomes ground potential and TR916
becomes off, thus causing the safety indica-
tor connected to TR916 to extinguish. In
addition, positive voltage also appears at
terminals 9 and 10 of IC903; TR910 and
TR911 become on; and the main amplifier
input is shorted. Note that, once the prote-
ction circuitry has operated, the circuitry
will remain in the “hold’’ condition even
though the abnormality is corrected. Thus,
if the safety indicator goes out, the power
should be turned off, and not turned on
again until first it is confirmed that there is
no abnormality.
(DRIVER) (POWER)
TREO! +B
TREIS
$-— OUTPUT
TR611 TR616
AW =B
Wi
+B
ae == (C903 3 (DRIVER) (POWER)
| TR610, +B
HOLD
A TR61S
—foerecrork CIRCUITRY |
| Co fence] | OUIEUL
| TR612,
| swITCHING L$ [SWITCHING |
-B;
TRE2
| ge = | oe
k- prtaien mn Osied
a
To Safety +B ae ae
TRSI6 SUPPLY
Indicator- ! TR909 Input ftch- s
Line (Reh,
DC PROTECTION
TR910 TRON Relay "CIRCUITRY
Fig. 10
mw ALIGNMENT INSTRUCTIONS ...... Main Amplifier Circuitry
¢ Main amplifier (ICQ) alignment
1. The “ICO” adjustment should be started about 5 minutes after
setting the power switch to the ON position.
2. Speakers switch to ‘‘push” position.
3. Connect DC voltmeter between TP601 and (+) speaker termi-
nal of right channel.
4. Adjust VR602 to 13 mV on DC voltmeter indication.
5. Connect DC voltmeter between Emitter (TR613) and @)
speaker terminal of left channel.
6. Adjust VR601 to 13 mV on DC voltmeter indication.
¢ Power level indication alignment
1. Connect AC VTVM to speakers terminal. (Left and Right channels)
2. Power display switch to “ON” position and display range
switch to “XO. 1” position.
. Selector switch to “AUX” position.
. Apply a 1kHz signal to “AUX” terminal.
. Adjust supply signal level to 12.6V ~ 12.7V output voltage.
3
4
5. Volume control to maximum position of set.
6
7
. Adjust VR801
until “200W”’ indicator lights up.
e¢ Power transformer tap selection circuitry alignment
Notes: o
Resistors connected to speaker terminals should
be of low tolerance (1% ~ +2%).
o Each channel to be adjusted separately.
1. Set volume control to minimum position and speaker
switch to ‘‘on”’ position.
2. Connect oscilloscope between TP1 and chassis for left
channel, and between TP3 and chassis for right channel.
(Set to voltage measurement range.)
3. Connect 6.50 resistor (or 12Q and 152 coil resistors in
parallel) to left channel speaker terminal.
4. Short TP2 and TP4 to chassis.
5. Adjust VR901 and VRQ02 so that TP3 output voltage is
from about OV to about 6V.
6. Connect 6.529 to right channel, and adjust VR903 and
V R904 so that TP1 output voltage is from about OV to
about 6V.
(Left and Right channels)
(Left channel) and VR802 (Right channel)
[SPEAKER TERMINAL] DC Voltmeter
ze . et
ro
rant
© 2
VREO2
= TP601
I<
MAIN AMP
VR601
Emitter
of TR613
nae
Ls
u——7 7
MAIN REMOTE. DISPI
~ (ON)
{SPEAKERS TERMINAL |
(LEFT) ale
20
ALcon)
LAY RANGE
om (X01)
OSCILLOSCOPE
iS)
150 4) 0,00)
eo
| Ase ‘ite | RaCHASSIS
' frria¢, |
| TP3
[vRs02
TR4
j
i SX TP2
CHASSIS
R
[vR903"
——— [vega]
DC VOLTMETER
TTY
@ @
Zaller
fetes
(Vy
7.
After
adjustment,
remove
6.50
and
wire
shorting
TP2
and
TP4.
8. Measure TR613 collector voltage when 8 speakers are
connected to speaker terminals.
9. Next, connect 60 speakers to speaker terminals, and
confirm
that
TR613
collector
voltage
is
about
10V
lower
than
voltage
measured
in
item
8.
[7]

Panasonic Technics SA-800 Specifications

General

Brand	Panasonic
Model	Technics SA-800
Category	Stereo Receiver
Language	English