Realistic RadioShack TRC-469 Service Manual

U

TRC-469

•

CUSTOM MANUFACTURED FOR RADIO SHACK M A DIVISION OF TANDY CORPORATION

TABLE OF CONTENTS

1.

SPECIFICATIONS

2.

DISASSEMBLY INSTRUCTIONS BLOCK DIAGRAM

3.

4.

CIRCUIT DESCRIPTIONS PLL CIRCUIT AMC CIRCUIT RF ATTENUATOR CIRCUIT

5.

ALIGNMENT INSTRUCTIONS

6.

TROUBLE SHOOTING HINTS

7.

IC, TR, DIODE & LED LEAD IDENTIFICATION

8.

IC AND COMPOUND PARTS INTERNAL DIAGRAMS

9.

FLEXIBLE P.C. BOARD(TOP VIEW)

10.

SWITCH P.C. BOARD(ANL, PA-MON-CB)

11.

MAIN P.C. BOARD(TOP VIEW)

12.

MAIN P.C. BOARD(BOTTOM VIEW)

13.

ADDITIONAL PARTS ON THE BOTTOM



   



 



3 4

5

6 7 10 7 9

10

10 11 - 14 14 16



17



18

19

20

21

22

14.

WIRING DIAGRAM

15.

ELECTRICAL PARTS LIST

16.

MECHANICAL PARTS LIST

17.

SCHEMATIC DIAGRAM

18.

EXPLODED VIEW



SEPARATE SHEET SEPARATE SHEET

24 - 32 33'34

23

1. SPECIFICATIONS

GENERAL:

Transmitter/Receiver

Communicating frequencies Operating voltage

Temperature and Humidity Range Transmitter/Receiver switching Antenna

Microphone



 Speaker Size



Weight Accessories



STANDARD TEST CONDITIONS:



Frequency synthesizing circuit with digital

phase-locked loop

26.965 MHz to 27.405 MHz (all 40 channels) 11-16V DC (positive or negative ground)

-20°C to +60° C and 10% to 90% Electronic (diode switching)

52 ohm (coaxial connector)



600 ohm Dynamic Type 8 ohm, 2 Watt 2-3/16" x 6-1/4- x

(5.5x 16 x 22.7 cm [HWD]) 5 lbs. (approx. ) (2.3 kg) DC Cord with in-line Fuse, Microphone and

Microphone Hanger and Mounting Brackets



(HWD) (approx.)

Battery supply voltage Modulation



Audio output power Audio output load

Antenna impedance



Ambient conditions

Temperature Humidity



TRANSM ITTER:

Frequency Tolerance 25°C 13.8 V RF Power Output AMC Range 50% — 100% Mod

Modulation Frequency Response (-6 dB)

Lower Frequency

a.

Upper Frequency 2500 Hz

b. Microphone Sensitivity 1 kHz 50% Mod Modulation Distortion at 1 kHz 80% Mod RF Power Output Uniformity Ch. to Ch.

Modulation Capability Positive/Negative

RF Power Output at 12.0 V Battery Drain

at no Modulation

a.

at 80% Modulation .

b.



450 Hz

13.8V

1000 Hz, 30% 500 mW 8 ohm 50 ohm (non-inductive load)

25°C ±5°C 50% to 70%

UNIT

W

dB

dB dB

mV

W

mA mA

DC

NOMINAL

0.0005 4 (Max.)

36

-

6

-

6

1

3

0.2

95/95

2.7

950

1550

LIMIT

0.003

3.6 — 4.0 30

6 ± 3 dB

-

2 8

0.5

80/85

2.2

1200 2000

3

RECEIVER:

(ANL: OUT)



UNIT



NOMINAL



LIMIT

Maximum Sensitivity

Sensitivity for 10 dB S/N AGC Figure of Merit 50 mV Overload AGC 50 mV — 1 V

Squelch Sensitivity at Threshold Squelch Sensitivity at Tight Adjacent Channel Selectivity

a. at ±10 kHz

Spurious Radiation Spurious Response Attenuation

a. 455/2 kHz

Image Rejection Ratio

a. -910 kHz

IF Rejection Ratio

a.

10.695 MHz

b.

455 kHz Cross Modulation Desensitization (3 dB Desens.)

at 100 pV

Audio Power Output

a.

Maximum

b.

10% THD

Audio Frequency Response (-6 dB)

a.

Lower Freq.

b.

Upper Freq.

THD at 500 mW Audio Output

a.

Input 1 mV 30% Mod b. c.

Signal-to-Noise Ratio at 1000 pV RF Gain Control Range S-Meter Sensitivity at "S9"

Oscillator Drop-out Voltage

Battery Drain

a.

at no signal b.

at Max. AF Output



450 Hz

2500 Hz

50% Mod 80% Mod



 

  



pV

p

V dB dB

p

V

pV

dB dB

dB

dB dB

dB

W W

dB

% %

% dB dB p V

V

mA mA



  

 



 



 

  

 

0.3

0.5 90

+4

1000

70 80

80

90

115

60

-6

45 40

100

250 800



  

0.25 

 



 



5



4



 

2



4



6

   

7



 

0.5 1

80

+6

-2



2

355 — 2820

60

70

80 90

50

55

4 3

-6 ± 3 dB

4 6

8 35 30 50 — 200 10

600

1500

PUBLIC ADDRESS:

Microphone Sensitivity for 4 W

Output Power at 1 kHz

Power Output

Maximum

a. b.

10% THD

Audio Freq. Response (-6 dB)

a.

Lower Frequency

b.

Upper Frequency

Battery Drain

a.

at no signal

b.

at Max. AF Output



450 Hz



2500 Hz



 

4

mV

W W

dB dB

mA mA



 

-6

300

1000

4

5 4



 

10

4

3

-6 ± 3 dB

700

1500

2. DISASSEMBLY INSTRUCTIONS

Figure 1



Figure 2



Figure 3

t

TO REMOVE TOP AND BOTTOM COVER (Figure 1 & 2):

Remove 4 screws from each side and a screw from top. Remove 2 screws from rear of the chassis. Slide top and

bottom cover toward rear of the chassis and remove.

TO REMOVE FRONT PANEL (Figure 3):

Remove 2 screws from each side.

Figure 4



Figure 5

ci

co

_ii

O

0

Ei

<

C7

ce

Q

4. CIRCUIT DESCRIPTIONS

PLL CIRCUIT:

The PLL circuit used in TRC-469 consists of 7 major parts: Voltage Controlled Oscillator(VCO), 1/N Divider, Phase Detector, Low Pass Filter,

[FVCO[ BY TP-1

12.279: 12.7202

RX

TR22

TX 16.725 — 17.165 MHz [TX. MIXER}

BUFFERI

IC3

V.C.O.



BUFFER

12C1Li

a.

BY TR14

COLLECTOR

RX 16.270-16.710 MI

TR14

TX 16.72517.165 MHI"

[F1I BY TP-3

RX 910 ^ 1,350 kHz

TR15

MIXER

t__

TX 1,365 — 1,805 kHz

Reference Oscillator (10.24 MHz), 1/2048 divider

and Code Converter ROM(Read Only Memory).

[Fstc1)

15.360 MHz

.120 MHz

L19



r

I

1> 

IS Amp

3.8V

3.5V

1.5V

1.2V CH1

TP2

0

RX = H

TR13

TX/RX

SW

TX = L

IC 4

PIN NO.

WAVE

FORM

IC4

PIN NO.

WAVE

FORM

NOTE:

22

21, 20, 7

+2.8V

+1.4V

RX . 910

—

1,350 kHz

TX = 1,365 — 1,805 kHz

c

.

,_______

10k4

CH

CH 1

H

CH 18

L

t

CH 23

H H

1



CH 40

L L L L

SCOPE WAVE FORMS FOR LEVEL REFERENCE

H = High (3.5V — 5 V)

L = Low (0V — 1V)

PIN NO. 1 through 4,5, & 6 are as in program input data chart.

,



CH23



CH40

Filter

—

WAVE FORM OF IC 4

18,17

DV

2

18 L

L L

2.4V DC —2.4V

19

3

1C

L

aVDC1 v

4

10

L

H

L

16,11

5V DC

15

H

=

LOCKED

L= UNLOCKED

where H

.

3.5

—

5V

L=

0

0 .

.= 1.0V

5

6

2A

2B

L

H

L

H

L

5.0V

3.5V

ov Low

IC4

13

10.240 MHz

9

H= RECEIVE

L = TRANSMIT Where FI = 3.5 — 5V

L = 0 — 1.0V

_

High

RX TX

4.8V P.P.

10

12

10.240 MHz

5.120 MHz

V

ilter Amp

PHASE

DETECTOR

C.P

PROGRAMMABLE DIVIDER 10 Bit

t

0

CHANNEL SELECTOR

.*12

k

5 kHz

SW

CODE CONVERTER

(ROM)

000

SWITCH

Hz

11 Bit DIVIDER

1/2,043



t

T Q

REF. OSC

V DD

V DC V DD

KEYING RX = 8V

The VCO is an oscillator which controls oscillation frequency in accordance with input voltage change. The VCO output is mixed with a signal in the transmitter or receiver circuitry. A portion of the

5V P.P.

VCO frequency is fed through TR14 Buffer Amp

--

and then added to TR 15. This frequency is mixed with a 15.36 MHz frequency then goes to IC4 (1/N divider).

"N" for the 1/N divider is determined by Channel

4V P.P.

Selector Switch whose output is selected by a Code Converter ROM.

As shown in the frequency chart, N is different between transmit and receive mode since only one crystal is used with this PLL circuitry.

The output from the 1/N divider is fed to Phase Detector. On the other hand, the frequency from the Reference OSC, 10.24 MHz, is divided to 5 kHz by 1/2048 divider and applied to another input of Phase Detector.

0-J

TX = CV

The Phase Detector detects the difference of these

two input signals and produces a voltage which

controls the VCO frequency. The Low Pass Filter integrates the output of the

Phase Detector which controls the VCO frequency and the 1/1\1 divider produces a 5 kHz frequency.

Thus the Phase Detector receives two input signals

(both 5 kHz). It compares the phase difference between the two, generating an error voltage,

which acts on the VCO to bring the two frequencies exactly in-phase. When this condition occurs, the PLL circuit is locked.

Fvco (the Frequency of the VCO) is changeable in

10 kHz increments, by varying the program divide

ratio, N.

For example, the divide ratio, N is programmed to

273 for channel No. 1 Transmit; therefore Fvco is calculated as follows:

Fvco = 15,360 + 5 x 273 = 15,360 + 1,365

= 16,725 (kHz)

In the same manner, Fvco for channel No. 2 through No. 40 is determined as shown in Table A.

Transmitter Local Oscillator The Transmitter local oscillator frequency of

10.240 MHz is produced by IC4 oscillator, IC4 and crystal, X'tal 1.

Table A shows Frequency Chart of Fvco and Divide Ratio vs. Antenna Frequency, and Program input data.

CIRCUIT FOR DETERMINING

FREQUENCY:

Output Frequency of the Transmitter Transmit frequency, Ft, is taken from the output

of the Transmitter Mixer IC1. One of the inputs of IC1 is the 1st local frequency,

Fvco, which is produced by the PLL Local Oscillator circuit. The other input is the transmitter local oscillator frequency of 10.240 MHz produced by JC4.

The sum of these frequencies determines the transmit frequency as follows:

Ft = Fvco = 10.240 (MHz)

PLL Local Oscillator Fvco, the output frequency of the VCO (Voltage

Controlled Oscillator), IC3, is fed to one of the inputs of the PLL Mixer, TR15.

The offset frequency, Fstd, 15.360 MHz (10.240 MHz = 2 x 3) is fed to another input of TR 15.

The input frequency to the Programmable Divider,

Fl, is calculated as follows:

Channel Selection Program The divide ratio of the Programmable Frequency

Divider in IC4 is determined through the Code

Converter and Transmit/Receive mode switch in

IC4 by the voltage supplied to the program input

terminals, Pin No. 1 through Pin No. 6 of IC4. The program input voltage for Pins 1 through 6 is

supplied from the Channel Selector switch accord-

ing to the Channel Number.

The Transmit/Receive mode switch in IC4 changes the divide ratio of the Programmable Divider by changing Pin 9 voltage (High level for Receive, Low

level for Transmit), to produce a 455 kHz change in VCO frequency when changing between the two modes.

When changing between Receive and Transmit modes, a varactor diode in the VCO IC, IC3, is switched in or out, respectively.

The bias voltage on this varactor is so designed that the VCO control voltage does not change when switching between modes, thus reducing lock-up time.

Fl = Fvco + Fstd (15.360 MHz)

F 1 is fed to the Programmable Divider in the PLL IC, IC4 and divided by N, through the Pro-

grammable Divider. The 10.240 MHz frequency produced by the Re-

ference Oscillator in IC4 is divided by 2,048 (the

Reference Frequency Divider in IC4) and the

resultant frequency, F2, is:

F2 = 10.240 MHz = 2,048 = 5 kHz

The output frequency of the Programmable Divider is compared with F2 at the Phase Detector in

IC4. When the frequency and phase of these two signals are precisely the same, the PLL circuit is "locked".

Therefore, Fvco is determined by the following formula.

Fvco = Fstd (15,360 kHz) + 5 x N (kHz)

CIRCUIT FOR PREVENTION OF UNAUTHORIZED FREQUENCY EMISSION:

This Transceiver has a built-in circuit which prevents transmission of unauthorized frequencies during the time when the PLL circuit is not locked or when the Channel Selector switch is between channels.

When the PLL circuit is not locked or the program data input is not for channel 1 — 40, pin 15 in IC4 produces a low level digital control signal. This

signal is fed to the base of RF signal Disable

Transistor, TR 16 (INSTANT STOP).

When the Channel Selector is switched from one

input (other than data required for channels

1 — 40). However, between channels, the Channel Selector produces a control signal at ground potential, and this signal is fed to the base of

RF signal Disable Transistor, TR 16.

In either case, when the base of TR16 is at low level, TR16 will not conduct and thus reduces the

supply voltage to the Amplifier stage inside IC1

to zero. This eliminates the RF signal output, and prevents any transmission on unauthorized fre-

quencies.

channel to another, it may produce a non-valid

TABLE A: FREQUENCY CHART OF Fvco AND DIVIDE RATIO N

Antenna

Frequency

(MHz)

26.965

26.975

26.985

27.005

27.015

27.025

27.035

27.055

27.065

27.075

27.085

27.105

27.115

27.125

27.135

27.155

27.165

27.175

27.185

27.205

27.215

27.225

27.255

27.235

27.245

27.265

27.275

27.285

27.295

27.305

27.315

27.325

27.335

27.345

27.355

27.365

27.575

27.385

27.395

27.405

Channel Number

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Divide

Ratio

(N) 273

275 277 281 283 285 287 291 293 295 297 301 303 305 307 311 313 315 317 321 323 325 331 327 329 333 335 337 339 341 343 345 347 349 351 353 355 357 359 361

For Transmit

F1

(kHz)

1,365 1,375 1,385 1,405 1,415 1,425 1,435 1,455 1,465 1,475 1,485 1,505 1,515 1,525 1,535 1,555 1,565 1,575 1,585 1,605 1,615 1,625 1,655 1,635 1,645 1,665 1,675 1,685 1,695 1,705 1,715 1,725 1,735 1,745 1,755 1,765 1,775 1,785 1,795 1,805

VCO

Frequency

(MHz)

16.725

16.735

16.745

16.765

16.775

16.785

16.795

16.815

16.825

16.835

16.845

16.865

16.875

16.885

16.895

16.915

16.925

16.935

16.945

16.965

16.975

16.985

17.015

16.995

17.005

17.025

17.035

17.045

17.055

17.065

17.075

17.085

17.095

17.105

17.115

17.125

17.135

17.145

17.155

17.165

Divide

Ratio

(N) 182

184 186 190 197 194 196 200 202 204 206 210 212 214 216 220 222 224 226 230 232 234 240 236 238 242 244 246 248 250 252 254 256 258 260 262 264 266 268 270

For Receive

F1

(kHz)

910 920 930 950 960 970

980 1,000 1,010 1,020 1,030 1,050 1,060 1,070 1,080 1,100

1,110 1,120 1,130 1,150 1,160 1,170 1,200 1,180 1,190 1,210 1,220 1,230 1,240 1,250 1,260 1,270 1,280 1,290 1,300 1,310 1,320 1,330 1,340 1,350

VCO

Frequency

(MHz)

16.270

16.280

16.290

16.310

16.320

16.330

16.340

16.360

16.370

16.380

16.390

16.410

16.420

16.430

16.440

16.460

16.470

16.480

16.490

16.510

16.520

16.530

16.560

16.540

16.550

16.570

16.580

16.590

16.600

16.610

16.620

16.630

16.640

16.650

16.660

16.670

16.680

16.690

16.700

16.710

1A

Program input data

1B

1C

HL L H H L L HL L H H H L HL L HL L H H L HL L H L HL L HL L HH L HL HL L H H L L HL L L HL L H H L HL L H Lit_ HL L

HL

H H

L

HL

L

HH H H L L

L

HL

L

H

HL

L

HH H

L

L L HL HL

L L L L

L HL HL

L L L L L

L HL

H H L L L L

L HL HL

H L L L

1D

L L

L L HL HL L L L L

L L HH H L

L L

L L HL HL L L L L

L L H H L

2A

L L L L L L L L

HL HL HL HL HL HL HL HL

H L

L L L L L L

H HH HH HH HH HH HH HH H H L

2B

L L L

L L L L L

L L H H H H H H H H H H H

H H L

AMC(Automatic Modulation Control) CIRCUIT:

The modulation control used in the TRC-469 functions as follows: Modulation signals from the mic are amplified by TR19 and IC2 and fed to the Transmitter's final RF Amplifier stage through Modulation Transformer Ti.

The level shift diode D19 (an 8-volt Zener diode)

"shifts" any voltage that exceeds a predetermined

level and this voltage is fed to the base of TR20 through D17 rectifier diode.

When the modulation signal from the mic increases past this predetermined voltage level, D17 applies a voltage to TR20, which causes base current flow. This reduces the equivalent C-E resistance of TR20. Note that R110 and TR20 C-E resistance forms a voltage divider for the audio signal applied to TR 19 Mic Amp. Thus this circuitry effectively

limits the level of modulation. VR5 sets the pre-

determined level which causes D17 to conduct.

RF (Radio Frequency) ATTENUATOR CIRCUIT:

To TX Amp

TR19

Mic. Amp

AMC control

Power Amp

IC2

Modulation line

TR20

R110



sMAP 

D17

— D18

T1 Modulation Transformer

D19 Level shift Diode

0

Modulation signal from the microphone

VR5 AMC control

This unit incorporates an RF attenuator circuit using P-I-N diodes; The Equivalent RF resistance of a P-1-N diode is controlled by the current which flows into the diode. Thus any receiver audio distortion caused by excess input signal from the antenna or cross modulation caused by RF gain can be prevented by these P-I-N diodes.

Since reverse-AGC is used with this Transceiver, the voltage on the AGC line becomes lower with strong antenna input signals (with no input signal, approximately 1.4 volts appears on the AGC line).

Furthermore, with no input signal, current from

the AGC line flows into the base of TR 1 which turns TR1 "on", causes collector current 1 flow and thus D23 will not conduct; therefore, no current will flow into D1 and D2 P-I-N diodes. As a result, there is no attenuation of the input signal from the antenna.

With a strong input signal, the voltage on the AGC

line decreases which turns TR1 "off" and decreases 1

2

current, which increases the collector voltage of TR1, current I current 1

3

will flow into D1 and D2 P-I-N diodes.

1

will flow through D23, and

Thus, the equivalent RF resistance of P-I-N diodes will drop and the excess input from the antenna to TR2 will be bypassed by these diodes.

In addition to the above, the attenuation level is controlled by changing VR1 (RF Gain) manually, which causes 1

4

current to flow, which varies the

attenuation level of Dl.

2

to

ANT 4 

VR101

RF

GAIN

ANT matching circuit

Vcc

TR1



Cl



*TX Power AMP

TR2. RF AMP

C144

T1

AGC LINE

* D1, D2 : PIN diode

5. ALIGNMENT INSTRUCTIONS

CHASSIS LAYOUT-ALIGNMENT POINTS:

ALIGNMENT OF PLL PORTION:

1. Test Equipment Required a.

Oscilloscope (0 — 50 MHz)

b.

Frequency Counter (0 — 50 MHz)

c.

DC Volt Meter (10 Volts maximum, 100K ohm/Volt)

d.

50 ohm Load

e.

DC Power Supply (13.8 V/2-Amp)

2. Alignment Procedure (See Pages 7 and 11)

Step

1

2

3

4

5

Preset to

Receiver mode ,

Channel 40

Same as step 1

Oscilloscope to secondary of L21 (TP4)

Frequency Counter to secondary of L21 (TP4)

Frequency Counter to Pin 22 of IC4 (TP3)

DC Volt Meter to Pin No. 4 of IC3 (TP2)

Frequency Counter to secondary of L17 (TP1)

PLL TEST EQUIPMENT SETUP

Connections

Adjustment

L21

VC1

L19

L18

VC1

Remarks

Adjust L21 for the maximum indication on Oscilloscope.

Adjust VC1 to obtain

10.240 MHz indication.

Adjust L19 to obtain

15.360 MHz indication.

Adjust L18 to obtain approx. 3.50V reading.

Adjust VC1 for

16.710000 MHz.

— 12

ALIGNMENT OF TRANSMITTER PORTION:

1. Equipment Required VTVM (full scale: 1V DC with RF Probe)

a.

b.

RF Output Power Meter

c.

Turnable Field Strength Meter (Wave Meter or Spectrum Analyzer)

d.

Frequency Counter (0 — 30 MHz)

2. Procedure (See Page 11)

e.

DC Power Supply (13.8V/2—Amp)

f.

50 ohm Load and Attenuator

g.

Oscilloscope (0 — 30 MHz)

h.

AF Oscillator

Step

1

2

3

4

5

6

8

Preset to

TX Mode, No Modulation, Channel 19

Same as step 1

Conditions

RF Output Power Meter to ANT. Jack J101. VTVM to TP5

RF Output Power Meter to ANT. Jack J101

Alignment

L15,16,17,

21

L11,13,14

Remarks

Adjust for a maximum indication on VTVM.

Adjust for a maximum indication on RF Output Power Meter.

Adjust to obtain

Same as step 1

Same as step 2

L11

Nominal 3.8 W of RF Output Power.

Tunable Field Strength Meter

Same as step 1

to Ant. Jack (J101) through a suitable load and attenuator

(Use Spectrum Analyzer if

L8

Adjust for minimum

2nd Harmonic Output.

available)

Repeat above adjustments, until no further change can be noted. TX Mode,

Ch19, 1 kHz 100mV applied to Mic Input for MOD

Audio Generator to Pin 4 of Microphone Jack (J3).

Oscilloscope to ANT. Jack (J101) through a

suitable load and attenuator

VR5

Adjust for 95% Modulation.

Check that RF Output

RF Output Power

7

Same as step 1

Meter to Ant. Jack

VR4

J101

Power Meter reads

3.8W, then adjust VR4 so that the Transceiver's Meter just approaches the 4 mark.

TX Mode, No Modulation, All channels

Frequency Counter to

Ant. Jack (J101) through a suitable load and attenuator

Check Frequency of

all channels.

TRANSMITTER TEST EQUIPMENT SETUP

Pi-n 4

TRC-469 Transceiver

AF

Oscillator 0-4

Si



MIC

JACK

-7(

AF VTVM

DC Supply 13.8V

00

RF Power meter

5012 Load

Attenuator

Oscilloscope I

1-1:36;r:

,-

73

Frequency

Counter

-J

Spectrum Analyzer

0 0

=1

00

000

_J

ALIGNMENT OF RECEIVER PORTION:

1. Equipment Required a.

Signal Generator (27 MHz Band, 1000 Hz, 30%

AM Modulation, Output Impedance = 50 ohm)

Audio VTVM

b.

2. Procedure (See page 11)

Oscilloscope

c.

Dummy Load (8 ohms, 5 watts, resistive)

d.

DC Power Supply (13.8 V, 2 Amp.)

e.

Step

1

2

3

4

SG Connection:

Frequency

To Ant. Connector (J101)

Freq: 27.185 MHz

Same as ste 1

Same as step 1

p

Preset to

Channel 19 Volume: Max.

Squelch: Min. Same as

step 1

Volume: Max. Squelch: Max.

Same as

1

p

ste



RECEIVER TEST EQUIPMENT SETUP

Audio

VTVM

To EXT. SPK. Jack(J2)

Same as step 1

Adjustment

L1,2,3,4,5,

6,7

V R1

VR2 (Squelch)

VR3

Remarks

Adjust for a max. Audio Output

Adjust for 2 V output with SG level of 0.3µV

Adjust

f

SG output level of 1000µV.

Adjust for a reading of S-9 on the Transceiver's S-meter with SG output level of 100 i.tV.

or

:, V

output with

8E2 Resistor

UNIT WILL NOT TURN ON

1.

Defective Power Switch

2.

Blown Fuse Defective Power Switch

3. Defect in Power Supply circuitry

4.

NO RECEIVE SOUND

1.

Defective external speaker jack

2.

Bad contact in the microphone jack Bad PTT switch in the microphone

3.

4.

Unlocked PLL circuitry Defect in Squelch circuitry

5. Defective PA-MON-CB switch

6.

6. TROUBLESHOOTING HINTS

NO TRANSMIT

Defective Microphone jack

1.

2.

Defective PTT switch on Microphone

Off-tuned main or local Oscillator

3.

4.

Defective PA-MON-CB switch

NO TX MODULATION

1.

Defective microphone and/or circuitry

2.

Defect in Modulation circuitry

FOR MORE HINTS, SEE BELOW

(Also Refer to Pages 7-10)

NO TRANSMIT

A.

Connect current meter in series with power cable and check the current reading for transmit mode:

If current reads more than 1 ampere (but less than 2 A.), it means the final output transistor is OK, so check for bad contacts or short circuits between PC Board and Antenna Connector. If current reads less than 0.5A: it indicates there is no drive to Final Transistor, so check drive or early RF stages.

B.

Defective PLL ? Check if voltage at the emitter of TR 16 is less

than 3 Volts. If less than 3V then PLL is un-

locked or Channel Selector Switch is between Channels. If more than 3V then PLL is OK.

Short Circuit in Transmitter Circuitry ?

C.

Voltage at emitter of TR21 should be less than 7 Volts (TX mode) should increase to more than 7 Volts in RX mode.

D.

If voltage reading is more than 7 Volts at the

collector of TR18, problem is not here. If voltage of more than 2 Volts is measured

between R101 and D16, then check microphone circuitry or D16 diode.

If RF voltage (27 MHz) is more than 200 mV

E.

P-P at TP-5, previous stages are OK.

F.

No voltage readings at collector of TR 10 and

TR 11: check D11 or T-1.

G.

No Channel LED light: If one particular segment does not light, the problem is with the entire LED or a bad contact in the Channel

Selector Switch or a broken Flexible Printed

Circuit. If LED does not light in any channel position, check D14 or FPC. With a defective

FPC, transmit will not operate.

NO CHANNEL LED LIGHT

If one particular channel does not light, check Flexible Printed Circuit Board or LED itself or

Channel Selector Switch. If no channel lights, check D16 diode or socket

for Flexible Printed Circuit Board.

NO TX MODULATION If receiver operates correctly but with no modula-

tion on TX, then problem should be TR 19, TR20 or short circuit in the microphone circuitry, since

audio power IC2 is used for both TX and RX

modes.



NO RECEIVE Before trouble shooting, be sure that Squelch

Control is fully CCW and microphone is connected.

A) Connect Signal Generator to antenna and see if

Signal Strength Meter (5 meter) deflects: S meter deflects:

Antenna through IF stage should be all right; check the circuit through ANL, Squelch and Audio amplifier. During the deflection of S

meter, negative voltage should be present at cathode of D6 diode if Detector circuit is normal.

S meter does not deflects:

To determine whether PLL is OK, check

following:

1.

A frequency in the range of 16 MHz should be present at TP-1 (0.5V P-P or more).

2.

The frequencies shown on page 11 should be correct when Channel Selector Switch is changed from CH 1 through CH 40.

3.

A frequency of 10.24 MHz should be present at TP 4 (0.2V P-P or more). If PLL is OK, then check circuitry through TR6, TR5, TR4, TR3, TR2 and TR1.

B) Check whether Audio stage operates: Connect

Speaker to PA Speaker Jack and set PA-CB switch to PA position. If click noise is audible when PTT switch is pressed, Audio Stage is OK. If no click noise, IC2 Audio Amplifier is defective or bad T-1 Transformer. (Transformer DC resistance should be approximately

0.5 ohm for both primary and secondary windings.)

C) Defective Audio Power IC ?

If voltage reading at pin 10 = 7V (VCC/2), IC2

should be all right.

D) Squelch is on all the time

TR7 is defective if voltage at the collector of TR8 is more than 5 volts. If reading is less than 2 volts, check TR9 circuitry and/or Squelch control's ground connection for cold

solder.

PLL CIRCUIT TROUBLESHOOTING HINTS

(also Refer to Page 7):

N

Check whether voltage reading on Pin 1 of IC3 is approx. 5.1 volts.

Defective Vcc line (5V).

Check whether there is RF

output of approx. 0.2

V P-P at secondary of L19.

Check whether there is RF voltage(0.2Vp-p) on Pin 2 of IC3.

Yes

Defective IC3, L18 open or

poor soldering.

Defective Switch. Defective Flexible PCB or Connector J4.

Yes

V

4, Yes

Defective TR22, L17 or poor soldering.

No



Defective TR15 or poor soldering.

No good

Check whether there is RF voltage on TP1.

(

Check whether BCD programs on Pin 1 thru 6 of IC4 are as specified in the Chart.



0

Check for RF signal of 16 17 MHz at collector of TR14.

Yes

Check for RF signal of 0.9 — 1.8 MHz on TP3.

Yes



Yes

Check whether there is approx. volts at CH1 and 3.5 volts at CH40 on TP2.

Yes

Check whether each Channel

Frequency matches the frequency

indicated in Frequency Chart.

Yes

Check whether voltage is 3.5 volts on TP2 at CH40.



Check whether voltage reading on Pin 8 of IC3 is approx. 2.5V on RX and

5.0V on TX.

Re-align L18.

4,

Yes

Defective IC4.

good

PLL is not

detective

A

1.8

Yes

Check whether there is Output of 5.120 MHz on

Pin 10 of IC4.

Defective L19 or poor

soldering.

Defective Crystal, or IC4 or poor soldering.

Yes

Defective TR14 or 1C3

or poor soldering.

Defective TR13 or poor soldering

7. IC, TRANSISTOR, DIODE & LED LEAD IDENTIFICATION

IC-1 TA7310P

TAPERED

Ec

ECB

MARKING

SIDE

MARKING SIDE

9

TR-1,7,9,13,16,19,20

2SC458

TR-12

2SC2076



MARKING

SIDE

IC-2 MB3710



B C E

MARKING SIDE

10

TR-3,4,5,6,14,15,22

2SC460

TR-8,17,18

2SA844

TR-2

2SC1342

IC-3 UHIC006

V

BCE

TR-10

TR-21



10



2SC2029

2SC1419

MARKING

SIDE

IC-4 KM5624

22

12

22

TR-11



ECB

2SC2029

MARKING

12

11

SIDE

1 2 3

D-201 TLR321

16

0 0 0 0

0 0

1------8

4

T TT

13 14 15 16

9

0 0



6 7 8 9 10 11 12

LR0702R

CATHODE

L-101

ANODE

AF



CATHODE

I



---



ANODE

D-9,10,12,15,16,24 1S2076

D-1,2 MC301

F

D-11,22

SR1K1

D-5,6,7,8,17,18,25

1N60AM

iDN

3

60

4

p

D-20,21,19 XZ086 D-13,23 XZ051

D14



BZ052

8. IC & COMPOUND PARTS INTERNAL DIAGRAMS

IC-1, TA7310P



IC-2, MB3710

- 1 8 -

RR 2

x 7 HA-013

,

1:K

9. FLEXIBLE P C. BOARD(TOP VIEW)

:``

w

-J

U)

10. SWITCH P.C. BOARD (ANL, PA-MON-CB)

S101

R115



-400 1/2 W

11. MAIN P.C. BOARD (TOP VIEW)

- 20 -

12. MAIN P.C. BOARD (BOTTOM VIEW)

21

13. ADDITIONAL PARTS ON THE BOTTOM

14. WIRING DIAGRAM

JI01

5P 101

SPI

N

VR101

LRF GAIN

50

KB

W30 BLK 3 - 60-3

REVISION

FOR

AUSTRALIAN MODEL OF TRC-469

Catalog Number: 21-9469

When servicing Australian model of TRC-469(Catalog Number 21-9469), refer to the Service Manual for TRC-469(Catalog Number 21-1527) as well as the following revision:

1. SPECIFICATIONS

Page 3

GENERAL:

27.225 MHz

to

90%

85%

to

+50°C

and

Communicating Frequencies

Temperature and Humidity Range



STANDARD TEST CONDITIONS:

Ambient conditions Humidity



27.015 MHz

(All 18 channels)



-30°C 10%

to

45%

to

Page 8

Page 9

The 4th paragraph should be as follows:

for channel

For example, the divide ratio, N is programmed to No.1 Transmit, therefore Fvco is calculated like this;

283

Fvco = 15.360 + 5 x 283 =15.360 + 1415

= 16.775 (kHz)

In the same manner, Fvco for channel No.2 through No:18 is determined as shown in Table A.

The 2nd and 3rd paragraphs should be as follows: When the PLL circuit is not locked or the program data input is

18,

not for channel 1 — control signal. This signal is fed to the base of RF signal Disable Transistor, TR-16 (INSTANT STOP).

When the Channel Selector is switched from one channel to another, it may produce a non-valid input (other than data required for channels 1 — Channel Selector produces a control signal at ground potential, and this signal is fed to the base of RF signal Disable Transistor, TR 16.

Refer to the attached revision of

pin 15 in IC4 produces a low level digital

However, between channels, the

18).

TABLE A: FREQUENCY

CHART OF Fvco AND DIVIDE RATIO N.

BLOCK DIAGRAM

3.

Page 6

Refer to the attached revision.

CIRCUIT DESCRIPTIONS

4.

Page 7

Refer to the revised PLL circuit diagram attached. The frequencies in the WAVE FORM IC4, pin No.22 should be

Rx = 960 kHz — 1170 kHz, Tx = 1415 kHz — 1625 kHz.

ALIGNMENT INSTRUCTIONS

5.

Page 12

2. ALIGNMENT PROCEDURE

Step 1, Preset to: Receive mode, channel Step 4, Remarks: Adjust L18 to obtain approx. Step 5, Adjustment: L17, Remarks: Adjust

18. L17

2.50V

for

reading.

16.530000 MHz.

Page 13

2. ALIGNMENT PROCEDURE

The channel number in step 1 and 6 should be Channel

10.

Page 14

15.

ELECTRICAL PARTS LIST

2. ALIGNMENT PROCEDURE Step 1, SG Connection Frequency: 27.125 MHz, Preset to:

Channel 10.

6. TROUBLESHOOTING HINTS

Page 15

S METER DOES NOT DEFLECTS: The channel No.40 in item 2

should read as channel 18.

Page 16

The first and third clauses from top-right hand side should be as

follows:

Check whether there is approx. 1.8 volts at CH 1 and 2.5 volts at CH18.

Check whether voltage is 2.5 volts on TP2 at CH18.

IC, TRANSISTOR, DIODE & LED LEAD IDENTIFICATION:

Page 17

The type number of IC-4 should be KM5626 Lead designation is same as KM5624.

8. IC & COMPOUND PARTS INTERNAL DIAGRAMS

Page 18

The type number of IC-4 should be KM5626 and refer to the

revised block diagram attached.

The resistor compound parts RR-1, HA-014 and RR-2, HA-013 should be deleted.

Page 26

Delete C-102, Ceramic Capacitor

Page 27

Add C-202 Ceramic Capacitor, 0.01/IF 25V K SL Add C-203 Ceramic Capacitor, 0.01/IF 25V K SL

Read type number of IC-4 as IC, KM5626

Page 30

Add R-201 Carbon Film Resistor, 1K-ohm 1/8W J RFPZ181024 Add R-202 Carbon Film Resistor, 1K-ohm 1/8W J RFPZ181024

Read type number of S-201 Rotary Switch as SR-198

MECHANICAL PARTS LIST

16.

Page 33

Add Pan Head Screw 3 x 8 for TR11

Page 34

Delete Bracket for Meter, F.C.C. Plate and Binding Screw M3 x 6

for speaker. Add: Spring Washer 2.6 diameter

Hexagonal Nut M2.6 Name Plate(rear of the chassis) Binding Screw M2.6 x 6



CKGZ511030



CKGZ511030



DDEY139001

...SSRY198001

MZSS123008

MZSN510026 MZSN430026 MDNP405640 MZSN192606

Pages 19 through 23

Refer to the revised parts layout attached.

Page 9

Antenna

Frequency

(MHz)

27.015

27.025

27.035

27.055

27.065

27.085

27.095

27.105

27.115

27.125

27.135

27.155

27.165

27.175

27.185

27.195

27.205

27.225

TABLE A: FREQUENCY CHART OF Fvco AND DIVIDE RATIO N

L: Low Level (Less than 1.0V DC)



Y23-

VCO

Frequency

(MHz)

16.320

16.330

16.340

16.360

16.370

16.390

16.400

16.410

16.420

16.430

16.440

16.460

16.470

16.480

16.490

16.500

16.510

16.530

Program input data

1A

1B

HL

H

L

H

L

H

L

H

L L

L

H

L

L HL

H

L

H

L

H

L

H

L

H

L

1C

L L L H H H H

L L L L L H H H H

L

1D

L L L L

L

•

L L H H L L L L L L L L H

Channel Number

1

2 3 4

5 6

7

8

9

10 11 12 13 14

15 16 17 18

Divide

Ratio

(N)

283 285 287 291 293 297 299 301 303 305 307 311 313

315 317 319 321 325

H: High Level (More than 3.5V DC)

For Transmitct-t-

VCO

Frequency

F1

(kHz)

1.415

1.425

1.435

1.455

1.465

1.485

1.495

1.505

1.515

1.525

1.535

1.555

1.565

1.575

1.585

1.595

1.605

1.625

(MHz)

16.775

16.785

16.795

16.815

16.825

16.845

16.855

16.865

16.875

16.885

16.895

16.915

16.925

16.935

16.945

16.955

16.965

16.985

T

Divide

Ratio

For Receive 47

(N) 192

194 196 200 202 206 208 210 212 214 216 220

222 224 226 228 230 234

F1

(kHz)

960 970 980

1.000

1.010

1.030

1.040

1.050 1,060

1.070

1.080

1.100

1.110

1.120

1.130

1.140

1.150

1.170

2A

L L L L L L L L L L H H H H HL H H HL H

2B

L L L L L L L

L

L L L L

L L

L

Page 18

1C4, KM5626

Page 7

PLL CIRCUIT DIAGRAM

Page 6

3. BLOCK DIAGRAM

Page 19



9. FLEXIBLE P.C. BOARD (TOP VIEW)

RR3

x 7 HA-013

4

I I I I I

LED SPACER

CATHOD SIDE

10. SWITCH P.C. BOARD (ANL, PA-MON-CB)

PA

MON

OUT

CB

Printed in Japan

RADIO SHACK

U.S.A.: FORT WORTH, TEXAS 76102

CANADA: BARRIE, ONTARIO L4M 4W5

AUSTRALIA

280-316 VICTORIA ROAD

RYDALMERE, N.S.W. 2116



Vii

A DIVISION OF TANDY CORPORATION

rm

TANDY CORPORATION

BELGIUM



PARC INDUSTRIEL DE NANINNE



5140 NANINNE



BILSTON ROAD, WEDNESBURY



WEST MIDLANDS WS10 7JN

U. K.

11A7



Printed in Japan

Realistic RadioShack TRC-469 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual