How it Works
Scott
Loading...
385R

Scott 385R Service Manual

Download
Page 1

Service Manual AM/FM Stereo Receivers

H. H. SCOTT, INC., 20 Commerce Way, Woburn, Mass. 01888 Tel. (617) 933-8800

w Manualship.com manuals search en

Page 2

CONTENTS

PAGE

  • 1. Specifications and revision information.
  • 3. Circuit description, tuner section.
  • 4. Circuit description, tuning indicators.
  • 6. Circuit description, audio amplifier.
  • 7. Circuit description, protection and power meters.
  • 8. Circuit description, temperature sensors.
  • 8. Test procedures.
  • 11. Fluorescent indicator panel lead codes.
  • 14. Parts location diagrams.
  • 17. Circuit diagrams.
  • 20. Exploded view and Notes.
  • 21. Parts list.
  • 32. Troubleshooting guide.

CAUTION NOTICE

The following safety precautions must be followed to assure continued reliability and safety against fire and shock hazard:

  • Replacement parts used during servicing of this appliance must have identical characteristics as those offered and recommended by H. H. Scott, Inc. In the interest of continued product safety we refer in particular to those safety critical components shown on the Replacement Parts List identified by the IEC Symbol "\(\Delta\)".
  • 2. A dielectric test is to be performed on each appliance following the re-assembly and before returning the unit to the customer.
  • The dielectric test to be performed on H. H. Scott, Inc. electric components serviced in the United States and Canada for use in these countries shall consist of not less than the following:*
    • A dielectric tester designed to have an output voltage that (1) has a sinusoidal wave form, (2) has a frequency that is within the range of 40-70 Hz, and (3) has a peak value of the waveform that is not less than 1.3 and not more than 1.5 times the root-mean-square value.
    • 1a) The sensitivity of the test equipment shall be such that when a 120,000-ohm resistor is connected across the output, the test equipment does not indicate unacceptable performance for any output voltage less than the specified test voltage, and does indicate unacceptable performance for any output voltage equal to or greater than the specified test voltage. The calibrating resistor is to be adjusted as close to 120,000 ohms as instrumentation accuracy can provide, but not more than 120,000 ohms.
    • The tester is to be connected per the instructions enclosed with the instrument, or as follows: a. The tester is connected to the power line receptacle and the power switch is turned on.
      • b. Sufficient time is allowed for the tester supply to stabilize and then the output voltage is adjusted for 1080 V.
      • c. Leads of the tester, usually marked GND and HV, are connected between chassis ground and both blades of the male plug of the power cord.
      • d. Switch tester to "test" and observe leakage indicator.
  • *Dielectric tests made by service personnel in countries other than USA and Canada must use test equipment and procedures specified by the safety agency serving that country.
COPYRIGHT H.H. SCOTT ELECTRONICS®

Printed in U.S.A. 11/82 029-1175-049

H.H. SCOTT ELECTRONICS®, Scottkit® and Scotsman~ are registered trademarks of H.H. SCOTT, Inc.

Page 3

Service Manual AM/FM Stereo Receivers

H. H. SCOTT, INC., 20 Commerce Way, Woburn, Mass. 01888 Tel. (617) 933-8800

wnloaded from www.Manualslib.com manuals search engine

Page 4

CONTENTS

PAGE

  • 1. Specifications and revision information.
  • 3. Circuit description. tuner section.
  • 4. Circuit description, tuning indicators.
  • 6. Circuit description, audio amplifier.
  • 7. Circuit description, protection and power meters.
  • 8. Circuit description, temperature sensors.
  • 8. Test procedures.
  • 11. Fluorescent indicator panel lead codes.
  • 14. Parts location diagrams.
  • 17. Circuit diagrams.
  • 20. Exploded view and Notes.
  • 21. Parts list.
  • 32. Troubleshooting guide.

CAUTION NOTICE

The following safety precautions must be followed to assure continued reliability and safety against fire and shock hazard:

  • 1. Replacement parts used during servicing of this appliance must have identical characteristics as those offered and recommended by H. H. Scott, Inc. In the interest of continued product safety we refer in particular to those safety critical components shown on the Replacement Parts List identified by the IEC Symbol "A"
  • 2. A dielectric test is to be performed on each appliance following the re-assembly and before returning the unit to the customer.
  • 3. The dielectric test to be performed on H. H. Scott, Inc. electric components serviced in the United States and Canada for use in
  • these countries shall consist of not less than the following:*
    • 1) A dielectric tester designed to have an output voltage that (1) has a sinusoidal wave form, (2) has a frequency that is within the range of 40-70 Hz, and (3) has a peak value of the waveform that is not less than 1.3 and not more than 1.5 times the root-
    • 1a) The sensitivity of the test equipment shall be such that when a 120,000-ohm resistor is connected across the output, the test equipment does not indicate unacceptable performance for any output voltage less than the specified test voltage, and does indicate unacceptable performance for any output voltage equal to or greater than the specified test voltage. The calibrating resistor is to be adjusted as close to 120,000 ohms as instrumentation accuracy can provide, but not more than 120,000 ohms. The tester is to be connected per the instructions enclosed with the instrument, or as follows:

a. The tester is connected to the power line receptacle and the power switch is turned on.

  • b. Sufficient time is allowed for the tester supply to stabilize and then the output voltage is adjusted for 1080 V.
  • c. Leads of the tester, usually marked GND and HV, are connected between chassis ground and both blades of the male
  • plug of the power cord.
  • d. Switch tester to "test" and observe leakage indicator.
  • *Dielectric tests made by service personnel in countries other than USA and Canada must use test equipment and procedures specified by the safety agency serving that country.

COPYRIGHT H.H. SCOTT ELECTRONICS®

Printed in U.S.A. 11/82 029-1175-049

H.H. SCOTT ELECTRONICS®. Scottkit* and Scotsman* are registered trademarks of H.H. SCOTT. Inc.

Page 5

SPECIFICATIONS

AMPLIFIER SECTION 355R 375R 385R
Minimum Continuous RMS Output
power perchannel
both channels driven into 8 ohms
from 20 Hz to 20 kHz
With no more than rated T.H.D. 		45 W 65 W 85 W
Total Harmonic Distortion
at rated output 		0.05% 0.04% 0.03%
Total Harmonic Distortion
at 10 Watt from 20 Hz to 20 kHz 		0.04% 0.03% 0.03%
Intermodulation Distortion at rated
output power; 60;7000 Hz;4:1 		0.04% 0.03% 0.03%
Signal to Noise Ratio,
shortened input, IHF-A network:
Phono (10mV, RIAA 1 kHz):
Others
Input Sensitivity
Phono MM 		81 dB
100 dB
2.5 mV 		84 dB
100 dB
2.5 mV 		84 dB
100 dB
2.5 mV
Phono MC 2.5 111 V 0.25 mV 0.25 mV
Others
Phono Overload 		150 mV
200 mV 		150 mV
M.M: 220 mV
M.C: 20 mV 		150 mV
M.M: 220 mV
M.C: 20 mV
Damping Factor, 1 kHz, 8 Ohm
more than 		50 60 60
Channel separation
at 1 kHz PHONO
at 1 kHz OTHERS 		55 dB
65 dB 		55 dB
65 dB 		55 dB
65 dB
Frequency Response at 1 Watt output
Phono RIAA 20 Hz—20 kHz:
Others 20 Hz—20 kHz: 		± 0.5 dB
± 1 dB 		± 0.5 dB
± 0.8 dB 		± 0.5 dB
± 0.8 dB
Filters
subsonic 6 dB/octave, -3 dB
Hi Filter 6 dB/octave, -3 dB 		Phono 18 Hz 30 dB/oct
7 kHz 12 dB/oct
Others 18 Hz 18 dB/oct 		Phono 18 Hz 30 dB/oct
7 kHz 12 dB/oct
Others 18 Hz 18 dB/oct 		Phono 18 Hz 30 dB/oct
7 kHz 12 dB/oct
Others 18 Hz 18 dB/oct
Tone Control Range
Base at 100 Hz
Treble at 10 kHz
Mid: at 1 kHz 		± 10 dB
± 10 dB
± 6 dB 		± 10 dB
± 10 dB
± 6 dB 		± 10 dB
± 10 dB
± 6dB
Loudness Contour
Volume control set to—30 dB
at 10 kHz
at 100 Hz 		+ 3.5 dB at 10 kHz
+ 7 dB at 100 Hz 		+ 3.5 dB at 10 kHz
+ 7 dB at 100 Hz 		+ 3.5 dB at 10 kHz
+ 7 dB at 100 Hz
GENERAL
Power requirement:
(Refer to rear panel for specified
voltage and frequency before
making any connections.) 		120V AC; 60 Hz 120 V AC: 60 Hz 120 V AC: 60 Hz
Power Consumption
Dimensions (W/H/D) 		280 W
5"/20"/13",
125mm/500mm/330mm 		370 W
5"/20"/13",
125mm/500mm/330mm 		480 W
5"/20"/13",
125mm/500mm/330mm
Net Weight 25¼ lbs. 11.5 Kgs. 28 lbs. 12.7 kgs. 30 lbs. 13.0 kgs.
Page 6

SPECIFICATIONS

FM SECTION 355R 375R 385R
Tuning Range 87.5 to 108.5 MHz 87.5 to 108.5 MHz 87.5 to 108.5 MHz
IHF sensitivity 10.8 dBf/1.9uV 10.3 dBf/1.8 uV 10.3 dBf/1.8 uV
50 dB quieting sensitivity Mono: 16.7 dBf/3.8 uV
Stereo: 37 dBf/39 uV 		Mono: 16.5 dBf/3.6 uV
Stereo: 37 dBf/39 uV 		Mono: 16.5 dBf/3.6 uV
Stereo: 37 dBf/39 uV
S/N ratio at 65 dBf Mono: 72 dB
Stereo: 67 dB 		Mono: 76 dB
Stereo: 70 dB 		Mono: 76 dB
Stereo: 70 dB
Distortion at 65 dBf Mono: 0.15%
Stereo: 0.25% 		Mono: 0.1%
Stereo: 0.2% 		Mono: 0.1%
Stereo: 0.2%
Frequency response + 1dB/ - 2dB 20 Hz—15 kHz 20 Hz—15 kHz 20 Hz—15 kHz
Capture ratio
Alternate channel selectivity 		1.2 dB
60 dB 		1.2 dB
60 dB 		1.2 dB
60 dB
Image rejection 75 dB 80 dB 80 dB
Stereo separation at 1 kHz 45 dB 50 dB 50 dB
Spurious response rejection 78 dB 78 dB 78 dB
Subcarrier rejection 55 dB 60 dB 60 dB
IF rejection (98 MHz) 90 dB 90 dB 90 dB
AM SECTION 355R 375R 385R
Tuning Range 515 to 1640 kHz 515 to 1640 kHz 515 to 1640 kHz
Usable sensitivity (bar ant.) 250 uV/m 250 uV/m 250 uV/m
S/N ratio 50 dB 54 dB 54 dB
Selectivity (1MHz) 45 dB 45 dB 45 dB
Image rejection 50 dB 50 dB 50 dB

REVISIONS MADE DURING PRODUCTION

355R, 375R

  • 1) R203 (FM IF CKT) deleted in certain production units to improve stereo separation.
  • 2) R 502 (Pwr. Supply) changed from 1.0K to 220 ohms.
  • 3) Pwr. transformer secondary voltage increased to provide better regulation and to accommodate additional voltage drop by added 4.70hm resistor (R510).
  • 4) CR511 changed from 1Z14 to 1Z15 to provide higher supply to tuner section.
  • 5) C218 increased from 1/50 to 10/15 to reduce trancient when unit switches in and out of MUTE.
  • 6) Q601 changed from KSA733Y to KSA708Y to improve reliability.
  • 7) C602 changed from 4.7/50 to 4.7/160 to improve reliability.
  • 8) CR602 deleted.
  • 9) Q501 changed from KSD 288-0 to KSD 288-Y to reduce voltage drop.
  • 10) R602 changed from 10K to 2.2K.
  • 11) C513 changed from 220mF to 1000mF to reduce protection circuit triggering with tone controls set at boost.
Page 7

CIRCUIT DESCRIPTION

—Tuner
FM Front End

The input section is designed using a balun coil that provides input matching for both 75 and 300 ohm transmission lines. The tuner section uses a MOSFET RF amplifier (Q1), transformer coupled to a bipolar mixer (Q2) for conversion. The local oscillator (Q3) is capacitively coupled to the base of Q2 where through the hetrodyne process a 10.7 MHz signal is produced for IF amplification.

FM IF Amplifier & Quadrature Detector (IC201)

Output of the FM front end is transformer coupled to the IF amplifier circuit, composed of the 10.7 MHz transformer (T201), a transistor stage (Q201), 3 dual element ceramic filters (CF201, 202, and 203) and one integrated circuit (IC201). This integrated circuit contains the limiter amplifiers, quadrature detector, AGC amplifier, mute circuits, A.F.C. circuit and audio amplifier. Within the IC, limiter output is fed directly to one quadrature input. This signal is also connected to pin 8 where it is phase shifted by external coil L201 and reapplied to the other quadrature input at pin 9.

Two audio signals, opposite in phase, are obtained from the quadrature detector. Output of the first amplifier (pin 7) is at a DC level which varies with detuning and is used to provide the DC level shift necessary to operate the center tuning circuits. Output from the second amplifier (pin 6) is the composite audio signal which is coupled directly to the multiplex IC. The composite signal is internally muted in IC201 whenever a positive voltage is applied to pin 5. Drive for muting supplied from pin 12 provides a positive voltage when input to the IC is reduced to a low level.

Multiplex Decoder HA1196.(IC301)

The multiplex decoder IC is functionally divided into 2 sections: the phase locked loop (PLL) signal generator and the stereo demodulator. The PLL consists of a 76 kHz voltage controlled oscillator (VCO) followed by two frequency dividers, producing 38 kHz and 19 kHz. The phase of this signal is compared with the phase of the incoming pilot signal and a difference signal is created which corrects the VCO and synchronizes the VCO signal to the pilot signal. Since higher order harmonics are contained in the phase difference signal, a low pass filter is used to eliminate these harmonics. A second phase comparator is used to sense when the PLL is locked to a pilot signal. The output of this comparator triggers the stereo indicator and connects the 38 kHz switching signal to the demodulator.

The demodulator circuit consists of two differential amplifiers operating in a switching mode controlled by the phase locked 38 kHz signal which demodulates the composite incoming signal into left and right outputs. These signals at pins 4 and 5 are coupled to external amplifiers Q302 and 352 which drive the left and right channel low pass filters.

A means of switching deemphasis of the FM audio signal has been incorporated in these models utilizing the external Post AMP FEEDBACK connections of the Multiplex decoder IC.

Block Diagram of HA1196 Multiplex Decoder

Block Diagram of HA1137 (IC201)

Page 8
AM Tuner Section

The AM incoming signal received at the AM antenna enters the RF section of IC101 and is amplified and coupled to the converter stage. Here the signal is changed to the universal 455 kHz intermediate frequency.

The local oscillator, operating 455 kHz above the incoming tuned signal, is achieved in the converter block in the IC with externally connected L102.

The 455 kHz signal is coupled through two stages of IF amplification, and to the detector. The detector output then appears as audio information at pin 12. This signal is then conducted through the low pass filter to further remove the 455 kHz component.

Block Diagram of HA1197 AM Tuner (IC101)

Drive for the signal strength indicator is provided at pin 15, this positive AGC voltage is coupled directly to the input (pin 8) of IC805.

Signal Strength Indicator (IC805)

The signal strength indicator is driven by the single inline package BA6104. This digital IC is designed using five comparators to drive the external display. It operates with an increasing DC voltage level applied to the input at pin 8.

In the 355R this IC is used to directly energize the LED display segments, in the 375R and 385R this same circuit is used to operate the signal strength segments of the fluorescent display tube.

The meter drive IC derives its inputs from pin 13 of IC 201 for FM and from pin 15 of IC 101 for AM. Sensitivity is set by control R835 while R214 provides adjustment for FM signal strength.

FM Tuning Frequency Display Circuit 375R, 385R

Frequencies generated by the FM local oscillator are coupled through a small value capacitor (C24) to the gate of FET Q4. Q4 is used for isolation and gain to trigger IC802. IC802 is a divide by 100 prescaler that divides the 110 MHz local oscillator frequency down to 1.1 MHz, the square wave out-

put is then applied through C811 to the input of IC 803, IC803 is a C-MOS LSI circuit designed to operate frequency indicators with up to five digits.

A four MHz crystal is mounted externally and wired to pins 19 and 20 of the IC.

This crystal is used as a reference for the clock which controls the gates within the IC.

Switching of the display frequency to FM is accomplished by applying FM B+ through regulator transistor Q801 to IC802 and by applying the FM B+ through a voltage divider R811 and R812 to pins 8 and 12 of IC803. FM B+ is also used to bias the series diode connected in series with the AM oscillator signal lead to pin 6 of IC 803. With this plus voltage applied to the diode cathode any signal that might appear on this conductor in the FM mode will not be conducted to IC803.

AM Tuning Frequency Display Circuit

Frequencies generated by the AM local oscillator within IC101 are coupled from pin 6 to the base of Q101, output of this emitter follower, is applied through a series diode directly to the input of IC803.

Switching of the display reading from FM to AM is accomplished by switching the FM local oscillator OFF and by removing FM B+ from IC802, pins 8 and 12 of IC803 as well as the bias voltage applied to the series diode used to conduct AM local oscillator signal to pin 6 of IC803.

Center Tune/Lock Circuit (Refer to Circuit Diagram)

The models 355R, 375R and 385R incorporate circuitry to both indicate proper FM tuning as well as to electronically correct a tuning error of up to ± 50 kHz caused by operator mistuning.

Center Tune

Center Tuning circuitry is composed of a dual op amp (IC804) with transistors Q802, 803, 804, 805 and 808 to operate the center tune indicator. When operating normally A.G.C. and mute voltages are applied to control transistors Q806, Q809 and Q810 which in turn determine when the center tune indicators will be turned on.

IC804 derives its control signals from pins 7 and 10 of the FM detector, IC201.

When the receiver is perfectly tuned the voltage across these two terminals will be zero, however as the receiver is tuned above the station carrier frequency the voltage as measured on pin 7 of IC201 will become lower with respect to pin 10. These pins of the detector IC are connected through isolation resistors to IC804.

IC804 serves two functions, first to invert the DC level applied to pin 2, secondly to stabilize the DC level at pin 7 which

ownloaded from www.Manualslib.com manuals search engine

Page 9

is used as a reference voltage for Q802 and Q803 as well as for Q814 and Q816 in the lock circuit.

With the reference voltage applied to Q802 and Q803 the output at pin 1 will now deviate plus as the receiver is tuned above the carrier frequency and minus when tuned below. When tuned high the positive voltage will cause Q802 to conduct and Q803 to be cut-off, with Q803 cut-off, Q804 will conduct and apply a positive voltage to the HIGH indicator. Conversly, tuning low will cut-off Q802 causing Q805 to conduct causing the LOW indicator to be illuminated. When either Q804 or Q805 is conducting the positive voltage at their emitter terminal will be applied to the base of Q808 thus causing this transistor to conduct thereby shunting the supply voltage through R827 to the center tune indicator.

Control Circuits

Operation of the CENTER TUNE circuits is dependant on proper alignment of the FM section and on the signal levels applied to the control transistors.

The CENTER TUNE circuit is also inhibited from operating at low input signal levels and from OFF station operation until a positive voltage is applied to the base of Q810, this will be accomplished:

  • a) when center tune voltage on 845 approaches zero, causing Q809 to cut off.
  • b) when voltage on pin 1 of IC 805 goes positive.

When Q810 conducts the base of Q806 will go low causing this PNP to conduct applying a positive voltage to diodes CR815 and CR816, without this positive voltage applied to the cathode of these diodes, the diodes act as a shunt to the DC level changes which operate the tuning indicators.

Lock Circuit

The lock circuitry, comprised of Q811, 812, 813, 814, 815 and 816 is described as follows:

When tuning of the receiver approaches an FM carrier the Plus Voltage at board terminal 845 will be reduced and finally reach zero on station.

When the voltage at the base of Q811 is reduced to below 0.6 volts the transistor will cut-off and the collector voltage will go to supply level. In this design, an intentional delay created by the R-C time constant of C824 and R838 has been incorporated.

When C824 is sufficiently charged Q812 will conduct pulling the collector down so that collector of Q813 will go high thus turning on the lock indicator (CR801).

When the lock indicator is OFF Q816 is fully conducting.

This condition sets a fixed bias on CRI which is a back biased varactor diode on the FM local oscillator section. The characteristic of this circuit is that the capacitance of the diode is directly proportional to the reverse DC voltage across it. Thus the diode with a fixed DC voltage contributes nothing to the tuning, acting only as a fixed capacitor. However, when the lock circuit is enabled and the indicator is turned on the collector/base voltage through R850 to O816 will be shunted by Q815 thus turning Q816 OFF and permitting the DC level change at the collector of Q814 to be applied to the varactor diode (CR1). The D.C. level applied to the base of O814 is derived from pin 1 of IC804 where, as indicated above, will become increasingly positive with respect to pin 7, when the receiver is tuned above the carrier, with this more positive voltage applied to the base of O814, the result will be a lower voltage across the varactor diode.

With a lower voltage the diode capacitance is increased until the carrier is center tuned, conversly, if the receiver is tuned below the carrier, a higher voltage will be applied to the diode with a resulting reduction in capacitance which will tune the receiver to the carrier.

Voltage change to the varactor is slow as determined by the R/C time constant of R849 on the display board and C220 on the tuner board.

The entire lock circuit is disabled by SW 7-2 when the LOCK/MUTE button is out.

Page 10

CIRCUIT DESCRIPTION

—Audio
Phono Preamplifier

These models use two separate operational amplifiers (IC901, 951) in a negative feedback configuration which provides the designer with means of gain adjustment and equalization.

Gain adjustment is fixed by resistors R914 and R915 while capacitors C910 and C911 provide the proper equalization to conform to the RIAA standard curve for recorded disc reproduction.

The circuit is powered by split supplies at a DC level suitable to provide the 200 mV overload capability at 1.0 kHz.

Tone Control

The tone control circuits (IC 401, 451) use of the high gain and low noise characteristics of the TA7322.

The tone control is a negative feedback type utilizing inverting Pin No. 3 for control.

Bass Control (R412)

As the frequency applied to the input of the IC decreases, the impedance of C411 increases thus reducing the signal applied to the treble control. Therefore at low frequencies the gain is mainly determined by the position of the bass control (R412L). Rotating the bass control toward C407 will boost the low frequencies by attenuating the feedback information below 1000Hz. Rotating the control toward C406 will attenuate low frequencies by reducing the circuit impedance thereby increasing feedback below 1000Hz.

Treble Control (R414)

As the frequency applied to the input increases the bass control will be shorted by C406 and C407 and the control will have no effect. However the impedance of C408 will decrease so that control R414L becomes the main feedback control. Rotating R414L toward R413 will increase feedback thus attenuating high frequencies. Rotating R414L toward R415 will reduce feedback and boost high frequencies.

Midrange Control (R419)

At 1 kHz the bass and treble controls have little effect on the gain because of the impedance of capacitors C406, C407, C409 and C410. Thus at midrange frequencies R419L will control the gain of the tone control circuit.

Power Amplifier -

The power amplifier design used in these models is a fully complementary design using a differential input amplifier composed of a matched transistor pair in a single package thus providing optimum common mode rejection and low DC offset.

With reference to one of the circuit diagrams, the first transistor (Q1401) provides the excellent common mode rejection and low DC offset.

Q1404 and Q1405 are used as voltage amplifiers to provide adequate signal level to driver transistors Q1406 and Q1407. Current gain is provided by the darlington connected driver/output circuit where Q1407 and Q1409 conduct for the negative swing and Q1406 and Q1408 conduct for the positive swing.

The output stage bias is set by the triple diode CR1401 and potentiometer R1412.

The amplifier is controlled by multiple feedback networks. DC feedback is provided through R1410 while R1411 and C1404 set the DC gain.

AC gain is determined by the ratio of R427 and R428.

Power Supply

The power supply in these models consists of a thermally protected power transformer with three separate secondary windings.

The first winding provides approximately 15.5-0-15.5 VAC which is rectified and regulated to provide the 12V DC supply for the tuner and part of the indicator circuits. Note: In later production the 15.5 VAC was increased to 18.0 VAC and zener changed to provide approx. 14V DC.

The second winding supplies approximately 82 VAC (385R) 72 VAC (375R) and 62 VAC (355R). This secondary voltage is rectified and filtered to provide a DC supply for the driver/output circuits, it is also regulated and further filtered for use in low level audio circuits.

The third winding, supplying approximately 5 VAC is used to provide filament current for the fluorescent displays.

Page 11

TURN-ON DELAY/ PROTECTION CIRCUIT

This circuit is mounted on PCB #3014-523-010 and consists of six transistors, one relay and an assortment of coils, resistors, diodes and capacitors. Q607 and Q657 are located on the Main Amplifier PC Board and are actually connected to this board via terminals 1408 and 603.

Delay

Audio Power to the speakers and headphones is delayed until relay contacts K601 and K651 are closed.

When power is switched ON, AC will be applied from the high voltage secondary to terminal 601 where it is rectified by CR601, filtered and applied to the base of Q603, at this time supply voltages to all circuits has been established and the voltage on the base of PNPQ602 has been reduced thus causing this device to conduct and to energize the relay coil thus closing the relay contacts.

Since the SAFETY INDICATOR is connected between supply and the relay coil this LED will be switched off when voltage to the coil is raised to near supply voltage.

Protection

Circuitry used to sense offset and overload on the output circuit is composed of Q606, 607 and Q657.

Under normal operating conditions, these devices are not conducting therefore the collector of each remains at approximately the + supply voltage.

In operation, whenever any one of the above transistors sense an overload or offset condition in the output circuit either from internal or external causes one or more of the transistors will conduct which in turn applies a more negative voltage to base of Q601, when Q601 conducts the voltage on the base of Q604 increases and causes Q604 to conduct which in turn causes Q605 to conduct thus short circuiting the positive voltage applied to base of Q603. This voltage is short circuited through Q605 and R604 to ground. Thus Q603 is cutoff and Q602 will not conduct to energize the relay.

Output Power Meter-355R-375R

(Although typical of both channels, reference is made only to left channel components)

The output power indicator circuit is comprised of Q817, Q818, IC806 and the fluorescent display tube, FL801.

Since IC806 requires a linear input, conversion of the audio information from logarithmic to linear is performed

by the diode/resistor network CR805, 806, 807, 808 and resistors R854, 855.

Amplified output of Q817 is AC coupled to a germanium diode and to the base of Q818. Since IC806 also requires a DC input the output of Q818 is DC coupled through an adjustment potentiometer and applied to the input of IC806.

IC806 is a C MOS LSI circuit which performs the analog to digital conversion and peak holding function for both channels. IC806 is directly connected to the fluorescent display tube and as DC level on the input of IC806 increases the gates at the output progressively turn on, thereby applying the supply voltage to the appropriate input of the display tube.

Output Power Meter-385R

The FL tube is driven by a MOS LSI (IC702) which performs the analogue to digital conversion and the peak holding for both channels. Since the input response of this IC is linear, a LOG signal conversion is required. This AC to DC conversion and LOG compression is performed by Diodes CR701, 751 and IC701.

Since this IC is a current activated device, its input voltage - sensitivity is determined by a series resistor to the inputs.

The auto-ranging circuit changes the sensitivity of the circuit by turning ON or OFF transistors Q-701 and Q-751.

The FLIP-FLOP (Q-702, Q-703) drives the input attenuator transistors and lights the corresponding decimal points on the display.

Need for change over, from low to high range is detected by diodes CR-711 and CR-710 which are connected to the last segments (most significant) of both channel displays, as long as the 2 least significant segments are lit, the range will remain in the high one. However if these segments turn off (underrange condition) for more than 3 seconds (determined by R-717 and C-709) the FLIP-FLOP will switch to the low range by O-705 triggering the transition.

These segments are monitored by diodes (CR-709 and C-708) which keep Q-705 in CUT OFF if these segments are lit.

Transistor Q-706 serves as system voltage regulator, utilizing the 8.2V internal reference of the LOG converter (IC701).

NOTE: Printed circuit board no. 3014-530-9606 is added in some production units to increase brightness of dots.

Page 12

TEMPERATURE SENSORS

Power Transformer Sensor

During production of these models certain production lots were fitted with a sensor attached to the power transformer designed to activate the protection circuitry if the power transformer temperature exceeded a predetermined level such as may occur under abnormal operating conditions.

If the receiver is made inoperable by the thermal sensor action the transformer must be allowed to cool before normal operation is resumed.

Circuit Theory

The subassembly voltage is supplied from a regulated source on the fluorescent display PCB as well as the positive voltage at term 603 of the protection board.

The regulated voltage applied to the first transistor, is used also to forward bias the triple diode and to provide a stable voltage on which to set the threshold for the second transistor.

With a known voltage drop across STV-3H at a given temperature the current through Q608 will be established thus setting the emitter voltage of the second transistor (Q609).

As the temperature applied to STV-3H increases the voltage drop across the diodes is reduced thus current through the first transistor is reduced and the emitter voltage drops. When the emitter voltage drops below the threshold set by the potentiometer, the second transistor will conduct thus activating the protection circuit to open the speaker relay contacts.

See page 10 for adjustment procedure.

Heat Sink Sensor

The 385R is designed with a sensor on the output transistor heat sink. This circuit operates in the same manner as the transformer sensor, however the design differences require a higher reference voltage setting for Q609. See page 10 for adjustment procedure.

ADJUSTMENTS
Equipment Required

Audio signal generator. Level meter. Oscilloscope. Digital frequency counter, 0 - 100 kHz. FM multiplex signal generator. DMM, high impedance. 455 kHz sweep generator. 10.7 MHz sweep generator.

AM IF Amplifier

  • 1) Apply 455 kHz sweep generator output to the unit AM antenna terminal.
  • 2) Connect scope to pin number 12 of IC101.
  • 3) Adjust T102 to obtain maximum and symmetrical display as shown.

AM Tracking

  • 1) Apply 600 kHz, 30% modulated with 1 kHz to the AM bar antenna. See test setup figure. (Distance between the AM bar antenna and emitting loop antenna should be 2 feet.)
  • 2) Adjust signal generator output so that a sine wave appears on the scope.
  • 3) Adjust T101 and L102 for maximum audio output on the level meter connected parallel with the scope. When turning core, always adjust signal generator output to maintain low input level. Do not change voltmeter range. Moreover, always keep the generator output as low as possible to avoid AGC action and to keep the measurements accurate.
  • 4) Adjust the AM loopstick antenna core for maximum output reading on the voltmeter.
  • 5) Shift generator frequency to 1,400 kHz with same modulation condition.
  • 6) Repeat step 2.
  • 7) Adjust OSC. trimmer for maximum voltmeter reading.
  • 8) Adjust Ant. trimmer for maximum reading on the voltmeter.
  • 9) Repeat items 3 through 8 for best tracking and maximum sensitivity.
FM IF Amplifier

1) Mute the FM local oscillator by shorting L5.

2) Connect the oscilloscope to pin 13 of IC201.

Page 13

  • 3) Apply 10.7 MHz signal from the sweep generator to L3 in the manner as shown above.
  • 4) Adjust T201 for correct figure as shown. It may be necessary to increase or decrease the sweep generator output for adjustment convenience.

FM RF Tracking

  • 1) Apply 90 MHz, 1 kHz and 100% modulated, 25 dBf signal level to the FM antenna terminals.
  • 2) Tune unit to 90 MHz.
  • Observe the oscilloscope connected to the Tape/Rec output terminal for symmetrical sine wave. If failed, adjust L5.
  • Adjust L1 and L2 for maximum level meter reading. Reduce input from the 25 dBf level as necessary to maintain noise on sine wave.
  • 5) Readjust the signal generator for 106 MHz, and retune unit.
  • 6) Repeat step 3. If failed, adjust the OSC. trimming capacitor mounted on the tuning capacitor.
  • 7) Adjust the trimming capacitors, for mixer and RF.
  • 8) Repeat as necessary until product specifications are met.
Center Tuning Adjustment

Connect DC DMM between chassis and pin 15 of IC201. Tune receiver to signal generator with output set at 65 dBf, carefully tune for lowest AGC voltage. (Assuming proper IF alignment this step assures tuning to center of IF band pass.) Reconnect DMM to PCB Terminals marked TUNING METER and adjust T202 for zero volts.

FM Distortion

With unit connected as above for tuning indicator adjustment, adjust T203 for minimum harmonic distortion.

Since there is some interaction between coil settings, repeat center tune and distortion adjustments for optimum results.

FM Signal Strength Display

  • 1) At 98 MHz, with receiver connected and tuned to FM generator, apply 65 dBf signal to unit antenna.
  • 2) Adjust R835 on Display Board until all segments are lighted.
  • 3) Reduce RF input to zero and note that both left and right center tune guide indicators are lighted.
Mute Threshold Adjust

  • 1) At 98 MHz, 20 dBf signal level, and set-up connected as above, tune unit with mute switch in the OFF position.
  • 2) Switch MUTE ON and adjust R226 until FM output is muted.
  • 3) Increase generator output to check for proper muting action.
  • 4) With LOCK/MUTE button IN, tune generator 50-100 kHz high and note that with approximately 8 seconds delay the circuit corrects to CENTER TUNE. Tune generator 50-100 kHz low and note same corrective action.
Multiplex Pilot Adjust

  • 1) Apply 98 MHz, 65 dBf signal to the unit with no modulation.
  • Adjust R303 for 76 kHz reading on the frequency counter connected between TP and chassis ground. A deviation of ± 200 Hz is acceptable.
Stereo Separation

  • 1) Apply 98 MHz, 65 dBf left channel signal to the unit modulated with 1 kHz, 9% pilot signal.
  • 2) Connect a digital voltmeter to the right channel Tape/Rec output terminal.
  • 3) Adjust R312 for minimum leakage (minimum level) on the voltmeter.
  • 4) Apply 98 MHz, 65 dBf right channel signal to the unit modulated same as step 1.
  • 5) Move digital voltmeter to the left channel Tape/Rec output terminal.
  • 6) Check for approximately the same leakage as in step 3.
Audio Adjustments

Equipment Required Audio signal generator. Digital multimeter. Speaker load resistors, 8 ohm 100 watt.

The following adjustments are the same for both the left and right channels.

Bias Adjustment

  • 1) Connect 8 ohm load resistors to the Speaker A terminals, and set the Speaker A switch to ON position.
  • 2) Turn the Volume control fully counterclockwise.
  • 3) Turn R1412 fully counterclockwise.
Page 14

  • 4) Using digital multimeter set meter to read 200 mV. Connect probes to emitters of Q1408, Q1409 (Voltmeter bias test points, L channel). Turn unit ON. Let it idle for at least one minute. Adjust R1412 for 30 mV across the resistors.
  • 5) Perform the same procedure for the right channel, except measure voltage at emitters of Q1458, Q1459 (voltmeter bias test). Adjustment is made with R1462.
  • Leave the amplifier on for about 30 minutes, then recheck measurement. A tolerance of ±25% is acceptable. Readjust if necessary.
Power Indicator Adjust (355R and 375R)

  • With all controls flat and volume at maximum, adjust input signal for an output level of 40 watts (no load) at 1 kHz.
  • 2) Adjust controls located on PWB behind front panel (R861 for left channel, R877 for right channel) for an output power reading of 40 watts.
Power Indicator Adjust (385R)

  • With all controls flat and volume at maximum, adjust input signal for an output level of 65 watts (no load) at 1 kHz.
  • Adjust controls R705 and R755 located on PWB behind front panel (R705 for left channel, R755 for right channel), for an output power reading of 65 watts.
Frequency Display Adjustment, (375R, 385R)

Adjust R803 located on PCB behind front panel for 7.0-8.0V on pin 13 of IC801. Note this voltage should be as low as possible within the above range while still maintaining reliable display under normal user conditions.

FM Display Adjustment.

  • Tune receiver to FM broadcast station of known frequency (the lock circuit may be used for accuracy). Adjust R808 until display reads the known station carrier frequency. Note: It is important that pot R808 be rotated left and
    • right through the range where the correct frequency is displayed ending in the center of the range.
AM Display Adjustment

Carefully tune receiver to center of AM station of known broadcast frequency. Adjust R809 until display reads the exact carrier frequency.

Power Transformer Temperature Sensor Adjustment.

  • 1) Connect DMM to measure DC voltage at test terminals.
  • With unit at room temperature 20 °C (68 °F) adjust R627 for 400 mV.
  • 3) If transformer temperature is within the range of 10-30 °C, the measured voltage should be corrected by -7.5 mV for each degree above 20 and +7.5 mV for each degree below 20.
Heat Sink Temperature Sensor Adjustment (385R)

1) Follow the above procedure setting the voltage at the test terminals at 900 mV when heatsink temperature is 20 °C.

Dial Cord Stringing

  • 1) Loosen the screw securing the drum to the variable capacitor shaft.
  • 2) Tie the end of the cord "A" as shown to the fixing protrusion on the drum.
  • 3) Wind the cord two turns around the drum then thread it through the rollers, etc., following the illustration.
  • 4) The the end of the cord to the coiled spring so that the proper tension of the dial cord is obtained.
  • 5) Align the pointer position for the correct frequency indication on the tuning dial.
  • 6) Secure the screw on the drum.

Fluorescent Indicator Panels (FIP)
Power

The models 355R and 375R utilize the same basic power display tube and both are driven by IC806, a type LC7555. The fundamental difference between the two tubes is the scale marking. Therefore, replacement parts should be ordered by part number for the appropriate model no.

The 385R utilizes a more sophisticated power meter, one which is the result of joint efforts by SCOTT and NIPPON ELECTRIC CO., LTD. Engineers to develop this multipurpose tube to SCOTT specifications.

Tuning

The tuning display tube used in the 375R and 385R provides indication of AM and FM signal strength. FM center tuning, and a frequency read-out of both the AM and FM bands.

Drawings on the following pages show the pin connections to the various elements of the above mentioned FIPS.

Caution

THESE FIPS, BEING MADE OF GLASS ARE EASILY DAMAGED. A LOSS OF VACUUM OR BREAKAGE CAN RESULT FROM PHYSICAL SHOCK OR STRESS DURING HANDLING AND INSTALLATION.

"FIP" LEAD CODE

The following pages contain outline drawings and lead codes for FIPs used in these models.

Page 15
4 25 26 27 28 29 30 31 32 33
a 8a 9a 10 11 12 NP NC VP F 		50 - SCO - SC ■ 1 2 ► FL 801
TYP. BG-32, BG-60
355R-375R
Pin no. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2 ectrode F NP SC 1a G 2a 3a 4a 5a 6a 1b 2b 3b 4b 5b 6b 7b G 3b 10 11 12 7 L 0.005 0.05 0.1 0.5 1.5 3 7 15
R 0.005 0.05 0.1 0.5 1.5 3 7 15
R 0.005 0.05 0.1 0.5 1.5 3 7 15

wnloaded from www Manualslib com manuals search engir

11

Page 16

Page 17

Page 18
Parts Location Diagrams 375R 385R Tuner, Amplifier and Protection

Page 19
Parts Location Diagram 355R Tuner, Amp, Protection

Page 20
Parts Location Diagram 375R, 385R Display

O

Parts Location Diagram Moving Coil Preamp.

Page 21

. ....................................

Page 22

wnloaded from www ualshib.com manuals search engin
Page 23

0

15.101 15201 15301 15.101 15201 15201 15.101 15201 15201

, .

Page 24

4

20

  • NOTES
  • Many transistors used in these models are identified by "KS" in place of the more familiar "2S" prefix. Genera these parts are electrically interchangeable. However, who replacing the SMALL SIGNAL devices, please observe proper transistor basing.
  • proper transitor basing. Pushbutton switch banks are available as a complete as bly or as individual sections. It is suggested that individ sections be replaced rather than the entire assembly. The sections be replaced rather than the entire assembly.
  • When ordering, specify both part number for asser and describe individual section by its front panel function When ordering replacement parts please give complete i
  • When ordering replacement parts please give complete formation as listed in the parts list section. In addition, please note the unit model number.
  • 4) Power transformer part numbers may vary from those liste here, therefore please give part number of old transformer as well as all information from parts list herein.
  • Input power of typical unit, properly adjusted at 120V line volume minimum, switched to FM is 35 watts, 0.5A.
Page 25

REPLACEMENT LIST OF MECHANICAL AND ELECTRO MECHANICAL PARTS – REFER TO 385R EXPLODED VIEW

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
1 6102-502-8101 CABINET 1.0T VINYL STEEL ALL
2 6103-500-3107 SIDE-CABINET-L 15T PLYWOOD VINYL ALL
3 6103-500-4102 SIDE-CABINET-R 15T PLYWOOD VINYL ALL
4 7334-500-1106 WASHER-CABINET P.P BLACK ALL
5 6804-502-2206 SPACER-CABINET 1.0 HIMERONE SHEET ALL
6 6022-505-6107 CHASSIS-BOTTOM 1.0T SPC-1 FZY ALL
7 6074-500-2101 FOOT RUBBER ALL
8 7702-507-7100 PANEL-FRONT AL EXTRU 355R
8 7702-507-7207 PANEL-FRONT AL EXTRU 375R
8 7702-507-7304 PANEL-FRONT AL EXTRU 385R
9 6463-500-7106 GUIDE-KNOB "F" ABS GREY ALL
10 7714-504-7207 PLATE-BACK VOL. 0.8T ALS ALL
11 7603-502-1109 MASK-TUNING ABS GREY ALL
12 7724-507-7104 KNOB-TUNING ALB ALUMITE ALL
13 7724-505-6103 KNOB-ROTARY ALB ALUMITE ALL
14 7724-506-0106 KNOB-BALANCE 94HB ACRYL CLR ALL
-15 7724-503-7108 KNOB-VOLUME ALB ALUMITE ALL
16 7653-501-4106 DIAL WINDOW 5.0T ACRYL CLR ALL
17 8012-504-1106 SCALE-DIAL 0.5T ALS OFFSET 355R
17 8012-504-1203 SCALE-DIAL 0.5T ALS OFFSET 375R
17 8012-504-1300 SCALE-DIAL 0.5T ALS OFFSET 385R
18 8014-502-7104 BLIND-SCALE ACRYL 0.5T × 373 × 13 ALL
19 8012-504-0208 SCALE-BACK 1.0T SPC-1 MET GRY 355R
19 8012-504-0101 SCALE-BACK 1.0T SPC-1 MET GRY 375R
19 8012-504-0305 SCALE-BACK 1.0T SPC-1 MET GRY 385R
20 6834-506-6103 SPACER RUBBER 3.5T ALL
21 8003-500-4101 CAP-POINTER ABS BLK ALL
22 7654-503-3104 FILTER-WINDOW ACRYL 0.5T 355R
22 7653-503-0102 FILTER-WINDOW ACRYL 0.5T 375R
22 7653-503-0209 FILTER-WINDOW ACRYL 0.5T 385R
23 0859-141-6008 TEFLON TAPE W 25.4×33Y×0.8T ALL
24 6613-506-1105 BRKT-GUIDE PNTR 0.8T SPCY-1 FZW ALL
25 5104-509-1100 SHAFT-TUNING MB R2 GC10 ALL
26 6603-500-6107 HOLDER-LED,S ABS NATURAL ALL
27 6614-583-2106 BRACKET, SCALE, R 1.0T SPC-1 FZW ALL
Page 26
SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN i.
28 5214-501-3104 PULLY GUIDE PA WHITE ALL
29 7394-500-5106 SHAFT GUIDE FE FZY ALL 1.111
30 6613-504-3109 BRACKET, SCALE L 1.0T SPC-1 FZW ALL
31 6603-101-2104 HOLDER-DIGITRON PS H/T 100% 355R, 375R
31 6603-101-3105 HOLDER-FL ABS BLACK 385R
32 6614-587-4108 BRKT-PWB (F) 1.2T S PC-1 FZW ALL
33 6022-505-5104 CHASSIS-FRONT 1.0T SPC-1 FZY 355R
33 6022-505-5102 CHASSIS-FRONT 1.0T SPC-1 FZY 375R
33 6022-505-5209 CHASSIS-FRONT 1.0T SPC-1 FZY 385R
34 7604-502-1109 MASK-KNOB 0.5T HIMERONE ALL
35 7723-500-5106 KNOB-PUSH "F" ABS ALL
36 6463-500-1106 GUIDE-KNOB PE SOFT NAT ALL
37 6654-507-9105 SUPPORT-G POINTER STS P1 1.0 ALL
38 6023-502-1100 FRAME-R 1.2T SPC-1 FZY ALL
39 5223-500-6104 WHEEL-DRUM ABS NATURAL ALL
40 6674-510-2100 SPRING, DIAL STS P1 1.0 ALL
41 6674-508-6103 STOP-SPRING SPS-27 0.3T ALL
42 4543-500-8102 SHIELD FENCE 0.3T TE SBC ALL ~
43 4544-503-1103 SHIELD PLATE-T 0.3T TE SBC ALL
44 4544-503-0108 SHIELD PLATE-P 0.3T TE-SBC ALL
45 5684-501-1101 HEAT SINK, TR 1.5T ALS ALL
46 6613-506-0100 BRACKET, TRANS 1.2T SPC-1 FZY ALL
47 5682-502-2105 HEAT SINK 2.5T ALS ALL
48 6654-507-8100 SUPPORT-B PNTR STS P1 1.0 ALL
49 6844-503-1201 WASHER-CABINET 0.8T FIBER ALL
50 6634-105-6409 CLAMPER-WIRE 0.5T SPC-1 FZY ALL
51 6634-100-1904 CLAMPER-WIRE SPC-1 0.6 TFT ALL
52 5683-501-3104 HEAT SINK A 2.0T ALS 355R
52 5682-501-1207 HEAT SINK SUB 1.5T ALS 375R, 385R
53 6023-502-0100 FRAME-L 1.2T SPC-1 FZY 355R
53 6023-502-0105 FRAME-L 1.2T SPC-1 FZY 375R, 385R
54 6022-505-4107 CHASSIS, REAR 1.0T SPC-1 BLK 355R
54 6022-505-4204 CHASSIS, REAR 1.0T SPC 1 BLK 375R
54 6022-505-4505 CHASSIS, REAR 1.0T SPC 1 BLK 385R
55 3339-543-0105 JACK, AUX ABS & 4P BLK ALL ( 1 )
56 3339-543-0202 JACK, AUX ABS & 2P BLK ALL
Page 27
SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
57 6834-502-0101 SPACER 1.0T×30×25 RUBBER ALL
58 3104-501-6109 TERMINAL, SCREW ABS ALL
59 7304-100-2100 WASHER-PLAIN 0.5T×3.5×7P1 FE FZY ALL
60 3303-500-1100 TERMINAL BD 5T SCREW ABS BLK ALL
61 6634-100-8103 CLAMPER, CORD HEYCO SR4N4 ALL
62 6634-100-7108 CLAMPER, CORD HEYCO SR 3P4 ALL
63 3304-501-6105 TERM BD PUSH DRP 0.03 4P ALL
64 6634-101-8106 BAND, CORD WIRE P.P BLACK ALL
65 4543-500-9107 SHIELD-FENCE FL 0.3T TE-S BC 375R, 385R
65 6603-103-7105 HOLDER-LED ABS NAT 355R
66 4543-501-0105 CAP-SHIELD, FL 0.3T TE-SBC 375R, 385R
66 6834-503-5109 MASK, LIGHT T RUBBER, SPONGE 6T 355R
67 6634-100-6103 BAND WIRE P.P BLK 355R
67 6613-506-4207 BRKT-PROT PWB 0.8T SPC-1 FZY 375R, 385R
68 4544-502-2105 SHIELD CAP-2 TE-SBC 0.3T 355R
68 5684-502-8109 HEATSINK, DIODE ALS 1.5T 375R, 385R
69 3124-100-7105 TAP-STUD 0.5T SPC-1 BT 2 355R
69 6614-591-6101 BRKT-BAND CAP 1.2T SPC-1 FZY 375R, 38 5R-*
70 3114-102-4208 LUG 0.3T TE-S BC 355R
70 6634-102-7201 BAND-CAP 0.8T SPC-1 FZY 375R, 385R
71 4544-500-5104 SHIELD FENCE TE-SBC 0.3T 355R
71 3934-103-1103 INSUL-TR NYLON 66 375R, 385R
72 6804-502-8106 SPACER-CAB 0.5T HIMERONE 375R, 385R
73 4544-500-5104 SHIELD-FENCE TE-SBC 0.3T 375R, 385R
74 3114-102-4208 LUG 0.3T T TE-SBC 375R, 385R
75 3934-500-7100 INSULATOR PLATE 1.0T FIBRE 375R, 385R
76 3124-100-7105 TAP-STUD 0.5T SPC-1 BT2 375R, 385R
77 4544-502-2105 SHIELD CAP-2 TE-SBC 0.3T 375R, 385R
78 6634-100-6103 BAND WIRE P.P BLK 375R, 385R
79 7654-565-3106 INDICATOR-SEL ACRYL CLEAR 385R
80 6604-513-2104 HOLDER-LED RUBBER, 94V-OW 385R
81 7018-130-0815 SCREW-FH + M3×8FE FZY ALL
82 7028-140-1010 SCREW-TH + M4×10 FE FZY ALL
83 7048-126-0437 SCREW-RH + M2.6×4 FE FZY ALL
84 7048-130-0616 SCREW-RH + M3×6 FE FZY ALL
Page 28
SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
85 7048-130-1213 SCREW-RH + M3 × 12 FE FZY 375R, 385R
85 7048-130-1019 SCREW-RH + M3 × 10 355R
86 7048-130-0412 SCREW-RH + M3×4 FE FZY ALL
87 7048-130-1514 SCREW-RH + M3 × 15 FE FZY ALL
88 7048-130-1019 SCREW-RH + M3 × 10 FE FZY 375R, 385R
89 7148-130-0619 SCREW-TAP, RH 1-3×6 FE FZY ALL
90 7148-530-0615 SCREW-TAP RH 2S-3×6 FE FZY ALL
91 7148-530-0819 SCREW-TAP RH 2S-3×8 FE FZY ALL
92 7148-530-0837 SCREW-TAP RH 2S-3×8 FZB ALL
93 7148-130-0831 SCREW-TAP RH 1-3×8 FZB ALL
94 7148-130-1012 SCREW-TAP RH 1-3×10 FZB ALL
95 7148-530-1212 SCREW-TAP RH 2S-3×12 FZY 355R
95 7148-530-1018 SCREW-TAP RH 2S-3×10 FZY 375R, 385R
96 7148-530-1212 SCREW-TAP RH 2S-3×12 FZY 375R, 385R
97 7158-530-0832 SCREW-TAP BH 2S-3×8FE FZB ALL
98 7098-130-0611 SCREW-FLANGE, RH + M3×6 FE FZY ALL
99 7154-100-6303 SCREW-TAP RH 2S-3×8 FE FZY ALL
100 7154-100-6701 SCREW-TAP RH 2S-3×2 FE FZY ALL -
101 7128-540-0810 SCREW-TAP TH 2S-4×8 FE FZY ALL
102 7128-540-1213 SCREW-TAP TH 2S-4×12 FE FZY ALL
103 7128-540-2032 SCREW-TAP TH 2S-4×20 FZB ALL
104 7304-100-2100 WASHER-PLAIN 0.5T×3.5×7.5P1 ALL
105 7304-500-2106 WASHER-PLAIN 4.5 P1×100 P1×1.5T ALL
106 7318-103-0014 WASHER-SPRING PI3.0 (3.1×5.9×0.7T) ALL
107 7328-204-0011 WASHER-TOOTHED BPI (4.3×8.5×T0.45 ALL
108 7208-113-0017 NUT-HEX 1M3 FE FZY ALL
109 7208-114-0010 NUT-HEX 1M4 FE FXY ALL
121 2309-120-0102 LED-SQUARE LN 217 RPL ALL
122 2309-119-0108 LED-SQUARE LN 317 GP ALL
123 3509-501-0203 SWITCH-SPK/PWR SFR 2045/SDRIR 355R, 375R*
123 3509-501-0504 SWITCH-SPK/PWR SFR 20451/SDR3R 355R, 375R*
123 3509-201-1502 SWITCH-SPK SRF 485 355R, 385R**
123 3509-501-0708 SWITCH-SPK SRF 4078 385R
124 1219-108-0105 VR-BASS GMPE 20FM7C100K 355R
124 1269-111-1503 VR-BASS GMPE 20FM7C100K 375R, 385R
125 1269-111-1309 VR-MID/TREB GM70E 20FM7C100K 355R

*Early production, grey power switch. **Later production using micro switch, see items 162, 163, 164.

Page 29
SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
125 1269-111-1406 VR-MID/TREB GM70E 20F C100K 375R, 385R
126 1299-102-0107 VR-VOL FJ60E 2SFM11 355R
126 1299-102-0204 VR-VOL FJ60E W250K/B100K 375R, 385R
127 3509-201-0507 SW-ROT-SLIDE SRZ VO45N 355N
127 3509-501-0106 SW-ROT-SLIDE SRZW045N 375R, 385R
128 3529-203-1702 SW-PUSH, FIL/LOUD SUF32 4C-4C, 2C ALL
129 3529-203-1809 SW-PUSH, MODE-TAPE SUF52 2C×29 ALL
130 3339-511-0203 JACK-EARPHONE HLJ0290-01-020 ALL
132 SEE TRANSISTOR LIS Г ALL
133 SEE TRANSISTOR LIST Г ALL
134 2189-105-1007 VARISISTOR-STV3H 7MA 1.6-1.8V ALL
135 1809-400-0101 VARICON-AIR С774Ј ALL
136 SEE CAPACITOR LIST ALL
137-146 PCB ASSYS ARE GENE ERALLY NOT AVAILABLE FOR REPI LACEMENT*
147 2319-101-0302 DIGITRON-PWR BG 32 355R
147 2319-101-0409 DIGITRON-PWR BG 60 375R
147 2319-101-0506 DIGITRON-PWR FIP 12AW 12YS 385R
148 2309-117-0102 LED METER LNO5202P 355R
148 2319-101-0205 DIGITRON-FREQ 7-LT-08 375R, 385R
149 2869-197-9003 TRANS-PWR W/O SENSOR 355R
149 2869-197-7031 TRANS-PWR W/SENSOR 355R
149 2869-197-9100 TRANS-PWR 375R
149 2869-198-0108 TRANS-PWR 385R
150 3334-500-1005 JACK-AC OUTLET 125V 15A S-16444 ALL
151 3053-806-3101 POWERCORD, AC STP1 18 BLK ALL
152 3304-501-6105 TERM BD, PUSH DRP 003 4P ALL
153 SEE PARTS LIST UND ER COILS ALL
154 3519-501-0509 SWITCH-INPUT SEL SSR 22602D 375R, 385R
155 3349-519-9100 SW, DENTENT, FLEX SWR 6300 375R, 385R
156 DEEMPHASIS PWB NOT AVAILABLE ALL
157 3519-201-0609 SW, SLIDE, DEEMP SSB 023N ALL
158 3934-501-110 INSULATOR, FIB-A 0.8T × 45 × 52 385R
159 3934-501-2108 INSULATOR, FIB 1.0T × 160 × 72 385R
160 6614-595-4103 BRKT-BWB, S 1.2T SPC-1 FZY 385R
161 5682-501-5107 HEATSINK, B 2.0T ALB BLK 385R
Page 30
SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
162 6614-592-9109 BRKT PWR, SW 1.0T SPC-1 FZY 385R
163 5244-500-3106 CAM-S/W 2.0T SPC-1 FZY 385R
164 3599-902-020 SW/PWR SDR3R 355R, 375R*
164 3579-101-0105 MICRO SW АН 715457 355R, 375R, 385R
165 3014-528-9109 PWB, THERM PROT CHECK AVAILABILITY 385R
166 3013-507-8102 PWB, DRIVE, FL CHECK AVAILABILITY 385R
167 3014-529-0107 PWB, LED FUNCTION CHECK AVAILABILITY 385R
168 2309-101-4103 LED LD 30A RED 3 P1 385R

୍ତ୍ରି

*Used in early production. (Grey pwr sw only).

DIODES

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
CR801 2309-119-0108 LED-SQUARE LN 317 GP ALL
CR301, CR603 2309-120-0102 LED-SQUARE LN 217 RP ALL
CR512, CR825
CR716, CR717 2309-101-4103 LED LD30 A RED 3PI ALL
CR718
2309-104-2102 LED-DELTA SLP 239B 355R Pointer
SEE SCHEMATIC
ALL MODELS 2169-301-2901 DIODE, SWITCHING 1SS53 See Schematic
CR-1 2169-501-1603 DIODE, AFC KS3302, 4-7.5PF ALL
CR507, CR508 2169-404-2200 DIODE-ZN WZ220 50MW 20.8-22.3V ALL 🛆
CR501, CR502 2169-201-0504 DIODE, RECTIFIER IN4001, 1A, 50V ALL 🛆
CR503, CR504 2169-201-1509 DIODE, RECTIFIER IN4142, 3A 400V 355R 🛆
CR505, CR506
CR509, CR510, CR601 2169-201-0601 DIODE, RECTIFIER IN4002, 1A 100V ALL 🛆
CR511 2169-403-9202 DIODE-ZN, BZ150 IW 13.8-15.6V ALL 🛆
CR902 2169-404-1409 DIODE-ZN, WZ-061 50MW 5.6-6.5V 375R, 385R 🛆
CR901 2169-404-6103 DIODE-ZN Wz120 500MW, 11,4-12.6V 375R, 385R 🛆
CR608, CR1401 2189-105-1007 VARISTOR-STV 3H 7MA 1.6-1.8V ALL 🛆
CR1451
CR1402, CR1403 2169-201-0708 DIODE, RECTIFIER IN4003, 1A,200V ALL 🛆
CR1452, CR1453
CR1404, CR605 2169-403-2207 DIODE, ZN, WZ-182 50MW, 16.8-19.1V ALL 🛆
CR810, CR811 2169-101-1403 DIODE, GER, IN60 IR 15UA 355R, 375R
CR860, CR861
Page 31

FUSES

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
4709-031-4004 FUSE NOR 125V 6A, 31, 8 UL 375R, 385R 🛆
F505 4709-031-3106 FUSE NOR 125V 5A, UL 355R 🛆
F801 4709-133-1402 FUSE W/LEAD SLO 125/250 0.5A UL all 🛆
F501, F502
F503, F504 4709-131-3309 FUSE W/LEAD NOR 125V, 8A UL ALL 🛆

INTEGRATED CIRCUITS

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
IC701 2119-101-4500 IC TA 7318P 385R
IC806 2119-201-1300 IC-DISPLAY LC 7555 355R, 375R
IC702 2119-201-3203 IC-DISPLAY LC 7556 385R
IC101 2119-201-0907 IC-AM IF HA 1197 ALL
IC201 2119-201-0402 IC-FM IF HA 1137W ALL
IC301 2119-201-1106 IC-MPX HA 1196 ALL
IC901, IC951 2119-401-0206 IC-OP TA 7322P ALL
IC401, IC451
IC801 2119-601-0301 IC-REG LA 5700 375R, 385R 🛆
IC802 2119-601-0204 IC-PRESCALER SP 8629 375R, 385R
IC803 2119-201-1203 IC-FREQ. DISP. LC 7258 375R, 385R
IC804 2119-401-0303 IC-OP NJM 4558 DD ALL
IC805 2119-201-2004 IC-SIG BA 6104 ALL
Page 32

RESISTORS SAFETY, CRITICAL COMPONENTS \triangle AND SPECIALTY ITEMS.

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
R214, R312 1249-102-0908 VR-SEMI SR19R B220K ALL
R226 1249-102-0403 VR-SEMI SR19R B22K ALL
R303, R808, R809 1249-102-0306 VR-SEMI SR19R B10K ALL
R861, R877
R1412, R1462 1249-102-0102 VR-SEMI SR19R B470 ALL
R627, R803 1249-102-1000 VR-SEMI SR19R B2.2K ALL
R835, R705 1249-102-0209 VR-SEMI SR19R B4,7K ALL
R755
R886 1249-102-0704 VR-SEMI SR19R B100K 375R
R504, R505 1049-301-3106 R-METAL OXIDE RSIP 3.3K-K ALL 🛆
R709
R506, R507 1049-301-2402 R-METAL OXIDE RSIP 820-K ALL 🛆
R509 1049-105-2202 R-METAL OXIDE RS3P 560K ALL 🛆
R1407, R1457 1049-301-0101 R-METAL OXIDE RSIP 10K
R1408, R1458
R1422, R1472
R1413, R1463 1049-301-1300 R-METAL OXIDE RSIP 100-K ALL 🛆
R1424, R1474
R1417, R1467
R1418, R1468 1049-301-1504 R-METAL OXIDE RSIP 150-K all 🛆

CRITICAL COMPONENTS A

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
R1421, R1471 1049-315-0104 R-METAL OXIDE RS2P 10J ALL
R1422, R1472 1049-315-0104 R-METAL OXIDE RS2P 10J 385R Only
R1423, R1473 1049-103-2002 R-METAL OXIDE RS2P 390-K 375R, 385R
R612 1049-105-1906 R-METAL OXIDE RS3P 330-K 385R
R613 1049-103-2400 R-METAL OXIDE RS2P 820-K 385R
R612 1049-103-1803 R-METAL OXIDE RS2P 270-K 375R, 355R
R1423, R1473 1049-103-1900 R-METAL OXIDE RS2P 330-K 355R
R613 1049-301-2402 R-METAL OXIDE RS1P 820-K 355R, 375R
R1422, R1472 1049-301-0101 R-METAL OXIDE RS1P 10K 355R, 375R
R1419, R1469 1035-905-0908 R-CEMENT WIRE RW5P 0.47K ALL
R1420, R1470

Page 33

TRANSISTORS

NOTE! TRANSISTORS ARE CONSIDERED CRITICAL COMPONENTS FOR SAFETY AND RELIABILITY REPLACEMENT PARTS MUST BE SAME TYPE OR EQUIVALENT

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
Q2, Q3 2139-301-0508 TRANSISTOR KSC 1674-0 ALL
Q101, Q201 2139-301-8508 TRANSISTOR KSA 838-0 ALL
Q202, 603, 604 2139-302-7409 TRANSISTOR KSA 945-Y ALL
606, 607, 657
802, 803, 808
809, 810, 811
812, 813, 814
815, 816, 817
818, 819, 820
Q701, 751 2139-302-7409 TRANSISTOR KSA 945-Y 385R
Q501 2149-401-2609 TRANSISTOR KSD 288-Y* ALL
Q801 2149-401-2609 TRANSISTOR KSD 288-0 375R, 385R
Q1401, 1451 2139-901-0104 TRANSISTOR KSA 798G ALL
Q1402, 1452 2149-102-6304 TRANSISTOR KSA 965 Y ALL
1403, 1453
1407, 1457 2149-102-6304 TRANSISTOR KSA 965 Y 355R
Q1404, 1454 2149-304-6405 TRANSISTOR KSC 2235 Y ALL
1405, 1455
Q1406, 1456 2149-304-6405 TRANSISTOR KSC 2235 Y 355R
Q1406, 1456 2149-403-3309 TRANSISTOR KSD 669 A-B 375R, 385R
Q1407, 1457 2149-201-7606 TRANSISTOR 2SB 649 A-B 375R, 385R
Q1408, 1458 2149-101-6107 TRANSISTOR KSA 1187 Y 375R
Q1408, 1458 2149-301-3207 TRANSISTOR KSC 2579 Y 355R
Q1408, 1458 2149-301-7605 TRANSISTOR KSC 2921 Y 385R
Q1409, 1459 2149-201-0300 TRANSISTOR 2SA 1187 375R
Q1409, 1459 2149-101-3209 TRANSISTOR KSA 1104 Y 355R
Q1409, 1459 2149-101-3607 TRANSISTOR KSA 1215 Y 385R
Q901, 951 2139-103-8603 TRANSISTOR KTA 970 BL 375R, 385R
Q902, 952 2139-305-6704 TRANSISTOR KTC 2240 BL 375R, 385R
Q601, 602 2139-103-7103 TRANSISTOR KSA 708 Y ALL
Q605, 804 2139-103-3802 TRANSISTOR KSA 733 Y ALL
805, 806
Q702, 703 2139-103-3802 TRANSISTOR KSA 733 Y 385R
704
Q608, 609 2149-301-3409 TRANSISTOR KSC 1008 Y 385R
Q1 2139-601-4806 FET 3SK 73 GR ALL
Q4 2139-601-0301 FET 2SK 212 375R, 385R

*Changed from D2880 to D288Y during production, D288Y is specified.

Page 34

AM ANTENNA, SEE EXPLODED VIEW INSERT

SYMBOL/
EXP. VIEW NO. 		PART NO. DESCRIPTION SPECIFICATI ON USED IN
67 7224-100-9102 NUT-HEX, CAP FE ENI ALL
68 7044-100-1106 SCREW-RH FE-FNI ALL
69 6614-117-3100 BRACKET-ANT BAR 1.0T SPC-1 FZB ALL
L101/70 2509-305-1016 COIL-ANT MW W/CORE CORE 10 PIX 120 ALL
99 6634-106-4101 BAND-BAR ANT 94HB ABS BLACK ALL

COILS, TRANSFORMERS, FILTERS & MISC.

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
L2, L3 2509-106-2104 COIL, FM ANT TR-A7JZ004S ALL
L1 2519-106-3104 COIL, FM ANT TR-A7JZ002S ALL
L4, L202, L103 2429-040-0302 COIL, CHOKE 2.2UH-K Q30 ALL
L5 2539-107-3107 COIL-FM OSC TR-A7JZ003S 355R, 375R
L5 2539-108-4105 COIL-FM OSC CFOR 12 P1010 385R
L201 2429-020-0708 COIL-CHOKE 18 UH-K Q30 F2R5 ALL
L102 2619-511-7093 COIL-RF, AM 340UH A-BASE ALL ~-
L1401, 1451 2429-060-0401 COIL, CHOKE SPKR 2R5UH-KQ50 ALL
T101*** 2619-010-4027 COIL, OSC MW 150UH A BASE ALL
T103 2749-118-0204 TRANS-IF, AM 7MM CAN ALL
T102 4529-313-0106 FILTER-CER, AM 7MM CAN ALL
T201 2739-501-0203 COIL-FM, MIX TRIO MMA002S ALL
T202 2739-503-0102 TRANS-FM, IF TRIO MM 013M ALL
T203 2739-501-0300 TRANS-FM, IF TRIO MM 014M ALL
LF301, 351 4529-415-0509 FILTER, LP 208 BLR 315 7R ALL
L101* 2509-205-1309 COIL-ANT, AM W/CORE CORE 10 PIX 120 355R, 375R
L101** 2509-305-1016 COIL-ANT, MW W/CORE CORE 10 PIX 120 ALL
¥801 4539-501-0403 CRYSTAL HC-18/U, 4.0 MHz 375R, 385R
L6 2509-105-5106 BALUN TV750301A2 ALL
K601 .4724-100-1201 RELAY, PROTECT MS4U DC24V 30MA ALL
3519-201-0609 SWITCH, SLIDE SSBO23N (Deemphasis) ALL
CF 201, 202, 203 4529-309-0103 FILTER, CERAMIC SFE 10.7 MA8 ALL

*Used in early production, and shown on exploded view. **Used in later production, see insert. ***Replacement part may be marked 2539-403-0204.

Page 35

CAPACITORS (SPECIAL OR CRITICAL COMPONENTS)

SYMBOL PART NO. DESCRIPTION SPECIFICATION USED IN
C515 1469-502-0706 CAP-CERAMIC AC 125 VAC 0.0047 ALL 🛆
C120 1509-452-1001 CAP-POLYSTYRENE CQ09S 50V 330-J ALL
C302 1509-452-1108 CAP-POLYSTYRENE CQ09S 50V 510-J
C311, C361
C511, C512 1619-018-2701 CAP-ELECTROLYTIC 50V 8200M PCB 355R 🛆
C511, C512 1619-018-3201 CAP-ELECTROLYTIC 63V 10000M PCB 375R, 385R∆
C416, C417, C418 1609-802-9908 CAP-ELECTROLYTIC NP CEO4W 100V 0.047M ALL 🛆
C466, C467, C468
C315, C365 1509-452-1700 CAP POLYSTYRENE CQ09S 50V 1100-J ALL
C314, C364 1509-452-1302 CAP POLYSTYRENE CQ09S 50V 560-J
C1 1809-400-0101 VARICON C774J ALL
C27 1829-511-0104 C TRIMMER ECV-12 W06×32E ALL

POWER/FREQUENCY DISPLAY CIRCUIT COMPONENTS

SYMBOL/
EXP. VIEW NO. 		PART NO. DESCRIPTION SPECIFICATION USED IN
FL801 2319-101-0302 FLUORESCENT TUBE B6-32 355R
FL801/147 2319-101-0409 FLUORESCENT TUBE B6-60 375R
FL701/147 2319-101-0506 FLUORESCENT TUBE FIP12AW12YS 385R,
IC806 2119-201-1300 INTEGRATED CIRCUIT LC7555 355R, 375R
IC702 2119-201-2303 INTEGRATED CIRCUIT LC7556 385R
IC701 2119-101-4500 INTEGRATED CIRCUIT TA7318P 385R
Q701, Q751 2139-302-7409 TRANSISTOR KSC945Y 385R
Q702, Q703, Q704 2139-103-3802 TRANSISTOR KSA733Y 385R
CR701-714, CR751 2169-301-2901 DIODE 1SS53 385R,
CR821 2169-301-2901 DIODE 1SS53 355R, 375R
R886 1249-102-0704 VR-SEMI SR19R B100K 375R
C831 1509-121-2702 CAP-POLYESTER M50V 0.12M-J 375R
CR820 2309-117-0102 LED METER LN 05202P 355R
CR827, CR828, CR829 2169-301-2901 DIODE 1SS53 355R, 375R
Page 36

TROUBLESHOOTING GUIDE

PROBLEM POSSIBLE CAUSE · CORRECTION
FM distortion. Low B + supply to FM IF. Verify that Q501 is KSD 288 Y
(See parts list).
Severe frequency jumping, or drift. Defective FM OSC trimmer. Replace trimmer cap C-27.
Oscillation at all levels, all inputs. 12V Reg. transistor Q501 oscillates at
VHF band. 		Increase value of C-509 from 0.001 to 0.047 ceramic disc.
Display does not light up. Check for broken wire or PCB track to FIP or IC. Repair as indicated.
-NOTE- -
To verify that FIP is or is not defective a new FIP n
in question with sufficient terminals connected to e
display elements. 		nay be connected directly across the part
nergize the filament B + and one or more
Protection circuit remains
activated. (Protection
LED ON).
  1. Check output bias and offset both channels.
  2. Units with temp sensor on transformer and all
  3. 385R, check for proper setting.
1) Adjust per test procedure
Protection circuit remains
activated. (Protection
LED ON). 		2) A number of production units have been
found with a 10 ohm resistor replacing R1417,
R1418, R1467 or R1468 causing severe offset. 		2) Replace this critical part with factory specified replacement-Adj. bias.
Occasional fuzzy sound at low level output. Oxidized relay contacts. Verify by shorting across contacts on
PCB, clean contacts with strip of clean
white paper pulled through contacts
under pressure or replace relay.
Display frequency stays at 87.5
or very slow AM to FM. 		Incorrect setting of regulated supply—IC 801. Adjust R803 for 7.5-8.0V at Pin 13 of IC801.
Poor FM sensitivity, does not switch to stereo. Defective ceramic filter. Replace filter with same color code.
Thump in speakers when switch-
ing through input functions.
Noisy tone/volume controls. 		Excessive DC offset in IC or leaky coupling/
feedback capacitors. 		Troubleshoot and replace parts as indicated.
355R FM tuning indicator
(green pointer LEDS) not
operating. 		FM detector alignment or defect. Defective component in circuit Q802-Q810 or IC804. Troubleshoot and replace parts as indicated.
Excessive high frequencies in phono mode. Incorrect equalization or improper cartridge loading. Check response to R1AA spec. Provide additional cartridge loading 100-300 pF.
Output section oscillates under certain speaker load conditions. Reactive loads causing circuit instability. Increase value of C 1417 and C1467 from 2 pF to 5pF.
Page 37

Page 38

SCOTT. The Name to listen to.

U.S.A. CORPORATE HEADQUARTERS

H. H. SCOTT INC. 20 Commerce Way Woburn, MASS. 01801

tel.: 617-933-8800

Loading...
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use