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R46 presents a 10K impedance load to the solar
cell in optical playback. C42, R5O, R54 and C48
for the input equalization network. The signal is
coupled to lCl (AN360) through eapacitor CL
Feedback to lCl is accomplished through a selecr-
able network consisting of C18, R?, R3, R5 and
C21. Position 1 and 3 of opticallmagnetic selectcr
switch provides a linear response of lCl, position
2 switches in the magneric playback equalization
required- Bass control VR-l, R8, C25, CZ4 end R9
form a low frequency boost and attenuation
equalization network- Treble control VR-2 and
C22, C23 provide for high frequency boost and
attcnuation. Thc signal frorn the tone controls is
fed through C6 tc pin 2 at lC2. Thcoutputof lC2
is coupled thnrugh C7 ta volume control VR-3,lo
pin I of lC3 through capacitor C28. Feedback for
lC2 isaccomplished through the network consisting
o f C 8 , R ' 1 2 , R 1 0 , R l 1 , C 2 7 , a n d R l 6 . F r o m l C 3
the signal is fcd to TR3, TR4 and TR5. TR6 and
TR? act as complimentary final output drivers to
an 8 ohm speaker through capacitor C13.
5ince this is a single ended common ground output,
Fig- #48
Rli4?t
Rtz rA
{so called O.T.L.
Output Transformer Less-
circuit), care should be taken to avnid a ground
loop condition which may result in amplifier
damage, when connccting the speaker ground to an
external earth or electrical ground.
D. Masnetic Record [49_d4r (NST-3 & NI!]
NST-3 & NT-3 models with magnetic record use a
special amplifier module which include the bias
and erase oscillator circuits. This circuit consists
of Tl and sscillator transistors TR8 and TR9.
ln magnetic recard, the Mag/Rec selector switch
set to the No. 3 position. Audio from the speaker
jack @ is rauted through the capaciror resistor
network C-38 and R41 to the magnetic record
head, At the samc timc bias and crasc currcnt is
supplied from the bias osillator to the cornbination
magnetic playback/rccord and erase head-
E. Amplifier Circuit Diagrams
'1. "N"
series Amplifier Diagram {See the end of
this manual] f, 73 '+-t P tY
2. "N" series Amp. P.C. Board Block Diagram {See
the end of this manua|\ P,7l
3. "N" series Amp- Frequency Response (See next
page)
llrAc sH.
to efaset
- 3 4 -
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