Block Diagram - Sony CRF-150 Service Manual

CRF-150
Limiter This diode clips the positive
D301 Peak of ac signal voltage devel
455 kHz am Ы signal on its
Am 2nd mixer conector,
0305
Power Supply
Fig 16 Selectivity selection circuit
Тһе CRF-150 uses a 4-pin ac cord for its power Bs Asi
supply and has a powerin jack for a house current
100V, 117V, 220V and 240V (for USA model 117V
VOLUME control The level of signal applied to
only). However, by using the SONY DCC-2A Car VR601 the power amplifier is deter-
tery Cord or standard flashlight batteries (six size
mined by the setting of VR601.
"D" cells), the CRF-150 can be operated away from
ап ас power outlet. Though diode 0502 prevents Amplifier 'Transistor Q401 amplifies the
а reverse current flow through the batteries when
0401
audio signal supplied
by
using а house current or car battery, it is better to VOLUME control VR601.
remove the flashlight batteries if they will not be
used for a while, Audio driver These direct-coupled stages
0402, 0403 amplify the audio signal supplied
by TREBLE control VR602
and BASS control VR603,
Sensitivity Selector
'The stage selectivity is obtained by using a Power amplifier This stage uses an OTL (output
ceramic filter (CF304) as а frequency-selective 0404, 0406 transformerless) push-pull class-B
by-pass centered at 455 kHz. This gives transistor amplifier, Thermistors CS401
Q304 a high gain at 455 kHz by preventing emitter and CS402 temperaturecompen-
degeneration of the signal at this frequency. Ву sate the base bias of Q404 and
connecting capacitor C372 in parallel with filter 0405.
СЕЗ04 (See Fig. 1-6), the BROAD selectivity band- Negative feedback from the out-
width is obtained. When the SHARP position is set, put of 0404 and 0405 to the
the bandwidth becomes narrow. However, greater emitter of 0403 improves the
sensitivity with less noise is obtained and a weak frequency response and reduces
signal can easily be heard, distortion,
1-4. BLOCK DIAGRAM
е Fig 17