Zenith B27B40Z Diagram

SAFETY PRECASAFETY PRECA

SAFETY PRECA

SAFETY PRECASAFETY PRECA

SERSER

VICE VICE

SER

SERSER

Only qualified service technicians who are familiar with safety checks
and guidelines should perform service work. Before replacing parts,
disconnect power source to protect electrostatically sensitive parts. Do
not attempt to modify any circuit unless so recommended by the
manufacturer. When servicing the receiver, use an isolation transformer
between the line cord and power receptacle.

SERSER

SER

SERSER

Use EXTREME CAUTION when servicing the high voltage circuits. To
discharge static high voltage, connect a 10K ohms resistor in series with a
test lead between the receiver ground and CRT anode lead. DO NOT lift
the CRT by the neck. Always wear shatterproof goggles when handling
the CRT to protect eyes in case of implosion.

X-RAX-RA

X-RA

X-RAX-RA

Be aware of the instructions and procedures covering X-ray radiation. In
solid-state receivers and monitors, the CRT is the only potential source of
X-rays. Keep an accurate high voltage meter available at all times. Check
meter calibration periodically. Whenever servicing a receiver, check the
high voltage at various brightness levels to be sure it is regulating
properly. Keep high voltage at rated value, NO HIGHER. Excessive high
voltage may cause X-ray radiation or failure of associated components.
DO NOT depend on protection circuits to keep voltage at rated value.
When troubleshooting a receiver with excessive high voltage, avoid close
contact with the CRT. DO NOT operate the receiver longer than
necessary. To locate the cause of excessive high voltage, use a variable
AC transformer to regulate voltage. In present receivers, many electrical
and mechanical components have safety related characteristics which are
not detectable by visual inspection. Such components are identified by a
# on both the schematic and the parts list. For SAFETY, use only
equivalent replacement parts when replacing these components.

GENERAL GUIDELINESGENERAL GUIDELINES

GENERAL GUIDELINES

GENERAL GUIDELINESGENERAL GUIDELINES

Perform a final SAFETY CHECK before returning receiver to customer.
Check repaired area for poorly soldered connections, and check entire
circuit board for solder splashes. Check board wiring for pinched wires or
wires contacting any high wattage resistors. Check that all control knobs,
shields, covers, grounds, and mounting hardware have been replaced. Be
sure to replace all insulators and restore proper lead dress.

WARNINGWARNING

VICE

WARNING

VICE VICE

WARNINGWARNING

VICING VICING

VICING

VICING VICING

Y RADIAY RADIA

Y RADIA

Y RADIAY RADIA

THE HIGH THE HIGH

THE HIGH

THE HIGH THE HIGH

TION AND HIGH TION AND HIGH

TION AND HIGH

TION AND HIGH TION AND HIGH

VV

OLOL

V

OL

VV

OLOL

TT

AA

GE AND CRGE AND CR

T

A

GE AND CR

TT

AA

GE AND CRGE AND CR

VV

OLOL

TT

V

OL

T

VV

OLOL

TT

TT

T

TT

AA

GE LIMITSGE LIMITS

A

GE LIMITS

AA

GE LIMITSGE LIMITS

UTIONSUTIONS

UTIONS

UTIONSUTIONS

SAFETY CHECKS — FIRE AND SHOCK HAZARDSAFETY CHECKS — FIRE AND SHOCK HAZARD

SAFETY CHECKS — FIRE AND SHOCK HAZARD

SAFETY CHECKS — FIRE AND SHOCK HAZARDSAFETY CHECKS — FIRE AND SHOCK HAZARD

Cold LeakaCold Leaka

Cold Leaka

Cold LeakaCold Leaka

Unplug the AC cord, connect a jumper across the plug prongs, and turn
the power switch on (if applicable). Use an ohmmeter to measure the
resistance between the jumped AC plug and any exposed metal cabinet
parts such as antenna screw heads, control shafts, or handle brackets.
Exposed metal parts with a return path should measure between 1M
ohms and 5.2M ohms. Parts without a return path must measure infinity.

Hot LeakaHot Leaka

Hot Leaka

Hot LeakaHot Leaka

Plug the AC cord directly into an AC outlet. DO NOT use an isolation
transformer. Use a 1500 ohms, 10W resistor in parallel with a .15µF
capacitor to connect between any exposed metal parts on the receiver and
a good earth ground. (See figure below.) Use an AC voltmeter with at
least 5000 ohms per volt sensitivity to measure the voltage across the
resistor. Check all exposed metal parts and measure voltage at each point.
Voltage measurements should not exceed .75VAC, 500µA. Any value
exceeding this limit constitutes a potential shock hazard and must be
corrected. If the AC plug is not polarized, reverse the AC plug and repeat
exposed metal part voltage measurement at each point.

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e Chece Chec

e Chec

e Chece Chec

ks fks f

ks f

ks fks f

g

gg

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e Current Chece Current Chec

g

e Current Chec

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e Current Chece Current Chec

or Receiveror Receiver

or Receiver

or Receiveror Receiver

kk

k

kk

s with Isolated Grs with Isolated Gr

s with Isolated Gr

s with Isolated Grs with Isolated Gr

oundound

ound

oundound

SET 4703SET 4703

SET 4703SET 4703

SET 4703

MODEL B27B40ZMODEL B27B40Z

MODEL B27B40ZMODEL B27B40Z

MODEL B27B40Z

High Voltage Shutdown Test .................. 1

IC Functions ........................................... 4

Important Parts Information ................... 3

Miscellaneous Adjustments .................... 1

Parts List ................................................. 4

Placement Chart ..................................... 1

Safety Precautions .................................. 1

Schematic Component Location ............ 3

Schematic Notes ..................................... 3

Schematics

A/V .................................................. 3

Audio ............................................... 2

PIP IF .............................................. 3

Power Supply .................................. 2

System Control ................................ 3

Television ........................................ 2

Service Mode Adjustment Chart ............ 1

Test Equipment....................................... 3

Tuner Information .................................. 1

INDEXINDEX

INDEX

INDEXINDEX

Technical Service Data

ZENITHZENITH

ZENITH

ZENITHZENITH

Model B27B40ZModel B27B40Z

Model B27B40Z

Model B27B40ZModel B27B40Z

Representative Model

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f

or ser

ff

or seror ser

Essential coEssential co

Essential co

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vicing a televicing a tele

vicing a tele

vicing a televicing a tele

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hematicshematics

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hematics

ScSc

hematicshematics

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vera

veravera

vision receivervision receiver

vision receiver

vision receivervision receiver

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4703

HIGH HIGH

VV

OLOL

TT

AA

HIGH

V

HIGH HIGH

VV

Turn receiver on, adjust customer controls for normal operation. Temporarily apply an external bias of

14.0V to the emitter of QX3002. The receiver should lose raster. If the receiver does not lose raster the
shutdown circuit should be repaired. Remove AC power, wait 30 seconds and test for normal operation.

The listing of any available replacement part herein in no case constitutes a recommendation, warranty, or guarantee by
SAMS Technical Publishing as to the quality and suitability of such replacement part. The numbers of the listed parts have
been compiled from information furnished to SAMS Technical Publishing by the manufacturers of the specific type of
replacement part listed.

Reproduction or use, without express permission, of editorial or pictorial content, in any manner, is prohibited. No patent
liability is assumed with respect to the use of the information contained herein.

© 2003

5436 West 78th Street
Indianapolis, IN 46268-4149

Printed in the United States of America 5 4 3 2 1

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SET 4703 SET 4703

SET 4703

SET 4703 SET 4703

P

PP

GE SHUTDOGE SHUTDO

OL

T

A

GE SHUTDO

OLOL

TT

AA

GE SHUTDOGE SHUTDO

WN WN

TESTTEST

WN

TEST

WN WN

TESTTEST

03PF02083

UPC

HERE

4703

ZENITHZENITH

ZENITHZENITH

ZENITH

For Supplier AdFor Supplier Ad

For Supplier Ad

For Supplier AdFor Supplier Ad

See PHOSee PHO

See PHO

See PHOSee PHO

TT

T

TT

OFOF

OF

OFOF

AA

CT AnnCT Ann

A

CT Ann

AA

CT AnnCT Ann

dress,dress,

dress,

dress,dress,

ual Indeual Inde

ual Inde

ual Indeual Inde

Component locationsComponent locations

•

Component locations

Component locationsComponent locations

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ts listts list

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ts list

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ts listts list

4703

xx

x

xx

MARCH MARCH

MARCH

MARCH MARCH

2003 SET 4703 2003 SET 4703

2003 SET 4703

2003 SET 4703 2003 SET 4703

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SET 4703 SET 4703

SET 4703

SET 4703 SET 4703

P

a

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TUNER INFORMATION

MAIN MAIN

TUNER TUNER

MAIN

TUNER

MAIN MAIN

TUNER TUNER

PinPin

Pin

PinPin

(1) AGC 2.2V 2.0V 1.7V
(2) TU 1.2V 4.1V 6.0V
(3) EN/AS 1.2V 1.2V 1.2V
(4) CLK 4.8V 4.8V 4.8V
(5) DATA 4.8V 4.8V 4.8V
(6) 9V 0V 0V 0V
(7) 5V 5.0V 5.0V 5.0V
(8) LOCK 0V 0V 0V
(9) 33V 33.5V 33.5V 33.5V
(10) IF2 0V 0V 0V
(11) IF OUT 0V 0V 0V

NOTE: VHF Low Band voltages taken on channel 2.

VHF LoVHF Lo

VHF Lo

VHF LoVHF Lo

VHF High Band voltages taken on channel 7.
UHF Band voltages taken on channel 14

SUB SUB

SUB

SUB SUB

w Bandw Band

w Band

w Bandw Band

TUNER TUNER

TUNER

TUNER TUNER

VV

OLOL

TT

AA

V

VV

VV

V

VV

GE CHARGE CHAR

OL

T

A

GE CHAR

OLOL

TT

AA

GE CHARGE CHAR

VHF High BandVHF High Band

VHF High Band

VHF High BandVHF High Band

OLOL

TT

AA

GE CHARGE CHAR

OL

T

A

GE CHAR

OLOL

TT

AA

GE CHARGE CHAR

TT

T

TT

TT

T

TT

UHF BandUHF Band

UHF Band

UHF BandUHF Band

MAIN MAIN

MAIN

MAIN MAIN

SUB SUB

SUB

SUB SUB

TUNER TUNER

TUNER

TUNER TUNER

(2)

(4)

(6)

(8)

(10)

TUNER TUNER

TUNER

TUNER TUNER

TERMINAL GUIDETERMINAL GUIDE

TERMINAL GUIDE

TERMINAL GUIDETERMINAL GUIDE

(1)

τ

τ

(3)

τ

τ

(5)

τ

τ

(7)

τ

τ

(9)

τ

τ

(11)

τ

TERMINAL GUIDETERMINAL GUIDE

TERMINAL GUIDE

TERMINAL GUIDETERMINAL GUIDE

MISCELLANEOUS ADJUSTMENTS

This receiver employs digital customer controls which are accessed through
the service menu. All adjustments were performed at reset unless otherwise
indicated. Record all the data values for all functions in the service menu
before making any changes.

HIGH HIGH

VV

OLOL

TT

AA

V

OL

VV

OLOL

GE CHECKGE CHECK

T

A

GE CHECK

TT

AA

GE CHECKGE CHECK

HIGH

HIGH HIGH

Tune in a picture. Set brightness and color to minimum. Connect a high
voltage probe to CRT anode. High voltage should read from 27kV to 29kV.

SERSER

VICE MENUVICE MENU

SER

VICE MENU

SERSER

VICE MENUVICE MENU

To access the service menu adjustments by using the remote transmitter
keypad, press and hold the menu button until the menu display disappears
from the screen. Key in 9, 8, 7, 6, and press the enter button.

To access the service menu adjustments by using the receiver keypad, press
the menu button until the display disappears from the screen. Without
releasing the menu button simultaneously press the adjust right and channel
up buttons.

The receiver is now in service menu mode with function 03 H Pos 16
displayed. The first line on the service menu is a version number of the
software used in the receiver. On the bottom is a date the module went
through the factory. Use the select up and down buttons to select function.
Use the adjust buttons to make changes to selected function. The function
00 F Mode (Factory Mode) is always set to 0. Only the first seven items in
the service menu can be brought up. Use the select key to select the 00 F
Mode function and change the adjustment to 1, now all the menu items will
be accessible.

NOTE: Set value of function 00 F Mode (Factory Mode) to 0 before exiting
the service menu mode. If not set to 0 the receiver will not shut off with the
remote or power button on the receiver.

HORIZONTHORIZONT

HORIZONT

HORIZONTHORIZONT

Tune in a crosshatch pattern. Call up service menu, select function 11, set
data value for slight overscan on both sides.

RF ARF A

RF A

RF ARF A

Tune in a picture. Adjust R1202 to a point where snow appears in picture,
then to a point where snow disappears.

COLOR COLOR

COLOR

COLOR COLOR

Tune in a crosshatch pattern. Set brightness, picture, and color to minimum.
Call up service menu, select functions 27, 28, and 29, set data values to 0.
Adjust data values for functions 30, 31, and 32 of the two least predominate
colors to obtain a white pattern. Tune in an active black and white channel
and adjust functions 27, 28, and 29 for best white to black tracking at high
and low brightness.

COLOR PURITY / CONVERGENCECOLOR PURITY / CONVERGENCE

COLOR PURITY / CONVERGENCE

COLOR PURITY / CONVERGENCECOLOR PURITY / CONVERGENCE

CRT and yoke are bonded. Color purity and convergence adjustments are
not recommended.

GCGC

GC

GCGC

TEMPERATEMPERA

TEMPERA

TEMPERATEMPERA

AL SIZEAL SIZE

AL SIZE

AL SIZEAL SIZE

TURETURE

TURE

TURETURE

PinPin

Pin

PinPin

(1) AGC 2.3V 2.1V 1.8V
(2) TU 1.2V 4.0V 6.0V
(3) EN/AS 1.2V 1.2V 1.2V
(4) CLK 4.8V 4.8V 4.8V
(5) DATA 4.8V 4.8V 4.8V
(6) 9V 0V 0V 0V
(7) 5V 5.0V 5.0V 5.0V
(8) LOCK 0V 0V 0V
(9) 33V 33.3V 33.3V 33.3V
(10) IF2 0V 0V 0V
(11) IF OUT 0V 0V 0V

NOTE: VHF Low Band voltages taken on channel 2.

VHF High Band voltages taken on channel 7.
UHF Band voltages taken on channel 14

VHF LoVHF Lo

VHF Lo

VHF LoVHF Lo

w Bandw Band

w Band

w Bandw Band

VHF High BandVHF High Band

VHF High Band

VHF High BandVHF High Band

UHF BandUHF Band

UHF Band

UHF BandUHF Band

(2)

(4)

(6)

(8)

(10)

(1)

τ

τ

(3)

τ

τ

(5)

τ

τ

(7)

τ

τ

(9)

τ

τ

(11)

τ

SERVICE MODE ADJUSTMENT CHART

SET 4703 PSET 4703 P

SET 4703 P

SET 4703 PSET 4703 P

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FUNCTIONFUNCTION

FUNCTION

FUNCTIONFUNCTION
221-01389221-01389

221-01389

221-01389221-01389

00 F Mode 0 0 0 - 1 Factory Mode. Normal setting is 0, when set to 1, all other functions are accessible.
01 Pre Px 0 1 0 - 1 Stores customer video menu picture preference (P RESET). 0 is custom,

02 V Pos 15 16 0 - 30 Vertical position of On Screen Displays (Menus & Captions).
03 H Pos 42 42 0 - 80 Horizontal position of On Screen Displays (Menus & Captions).
04 Level 1 1 0 - 2 ­05 Band 0 0 0 - 7 This setting depends upon input signal. 0 Broadcast Fixed, 1 CATV AFC,

06 AC On 0 0 0 - 1 Enables AC Power On feature.
07 RF Brt 15 14 0 - 31 RF Brightness.
08 Ax Brt 15 14 0 - 31 Auxiliary Brightness.
09 Max Con 63 35 0 - 63 Maximum Contrast.
10 V Size 38 24 0 - 63 Vertical Size.
11 H Size 63 31 0 - 63 Horizontal Size.
12 V Phase 42 46 0 - 63 Vertical Phase.
13 H Phase 0 13 0 - 63 Horizontal Phase.
14 H Osc 7 9 0 - 31 Horizontal Osc.
15 S Corr 7 7 0 - 31 S Correction.
16 V Linea 7 7 0 - 15 Vertical Linearity.
17 Pin Amp 63 23 0 - 63 Pin Amp.
18 C Pin 63 30 0 - 63 Corner Pin.
19 Trapez 15 7 0 - 15 Trapezium.
20 EHT Com 7 15 0 - 15 EHT Comp.
21 AFC Bow 7 7 0 - 15 AFC Bow.
22 AFC Ang 7 7 0 - 15 AFC Angle.
23 Up V Lin 6 6 0 - 15 Upper Vertical Linearity.
24 Lo V Lin 0 0 0 - 15 Lower Vertical Linearity.
25 AFC G 1 0 0 - 3 AFC Gain.
26 EWDC 1 0 0 - 1 EWDC.
27 R Cut 0 8 0 - 15 Red Cutoff.
28 G Cut 0 1 0 - 15 Green Cutoff.
29 B Cut 0 0 0 - 15 Blue Cutoff.
30 R Gain 31 48 0 - 63 Red Gain.
31 G Gain 31 35 0 - 63 Green Gain.
32 B Gain 31 30 0 - 63 Blue Gain.
33 Dynam C 0 0 0 - 1 Dynamic C Video.
34 Gamma 0 0 0 - 3 Gamma Register.
35 DCTran 1 1 0 - 1 DCTran Video.
36 C Bpf 1 0 0 - 1 C Bpf Video.
37 C Trap 1 1 0 - 1 C Trap Off Video.
38 FSC Sw 0 0 0 - 1 FSC Sw Video.
39 ABL Mode 1 1 0 - 1 ABL Mode Video.
40 ABLVTH 1 1 0 - 1 ABLVTH Video.
41 6 Keys 1 1 0 - 1 Set to 0 for the 10 key keyboard, set to 1 for the 6 key keyboard.
42 A Att 9 7 0 - 15 Audio Input Attenuator.
43 A VCO 31 31 0 - 63 Audio Voltage Controlled Oscillator.
44 A Filter 31 27 0 - 63 Audio Filter.
45 ASpectral 31 12 0 - 63 High Frequency Separation.
46 W Band 31 31 0 - 63 Low Frequency Separation.

DD

AA

TT

D

A

T

DD

AA

TT

VV

ALUEALUE

V

ALUE

VV

ALUEALUE

AA

A

AA

ON-SETON-SET

ON-SET

ON-SETON-SET
VV

ALUEALUE

V

ALUE

VV

ALUEALUE

VV

ALUEALUE

V

ALUE

VV

ALUEALUE

RANGERANGE

RANGE

RANGERANGE

NONO

TESTES

NO

TES

NONO

TESTES

1 is preset stored.

3 ICC AFC, 4 Broad cast AFC, 5 CATV F ixed, 6 HRC Fixed, 7 ICC Fixed.

FUNCTIONFUNCTION

FUNCTION

FUNCTIONFUNCTION
221-01389221-01389

221-01389

221-01389221-01389

47 PIP X1 17 20 0 - 254 Horizontal position on left side.
48 PIP Y1 25 23 0 - 254 Vertical position on left side.
49 PIP X2 113 117 0 - 254 Horizontal position on right side.
50 PIP Y2 143 151 0 - 254 Vertical position on right side.
51 PIP Adj 2 3 0 - 15 Picture In Picture Adjustment.
52 PIP Y DL 4 1 0 - 15 Picture In Picture Y Delay.
53 PIP Y Off 31 31 0 - 31 Picture In Picture Y Offset.
54 PIP ACC 20 20 0 - 63 Picture In Picture ACC Level.
55 P BGST 10 10 0 - 63 Picture In Picture BG Stat Level.
56 PIP HX 22 25 0 - 63 Picture In Picture HX.
57 PIP VXS 37 38 0 - 63 Picture In Picture VXS.
58 PIP R Con 50 14 0 - 63 Picture In Picture Red Contrast.
59 PIP G Con 50 15 0 - 63 Picture In Picture Green Contrast.
60 PIP B Con 50 17 0 - 63 Picture In Picture Blue Contrast.
61 PIP Comp 2 2 0 - 3 Picture In Picture Comp.
62 YUV Brt 10 0 0 - 31 YUV Sub-Brightness.
63 Min Con 10 25 0 - 31 Minimum Contrast Value.
64 F Jacks 1 1 0 - 1 Front Jacks.
65 PIP Brt 200 201 0 - 254 Picture In Picture Brightness.
66 Xtal 0 0 0 - 1 Select Crystal or RC circuit Oscillator for OSD.
67 Min Brt 25 25 0 - 63 Custom Minimum Brightness.
68 Max Brt 35 35 0 - 63 Custom Maximum Brightness.
69 GM PIP X 15 15 0 - 50 PIP X position for gemstar.
70 GM PIP Y 17 17 0 - 30 PIP Y position for gemstar.
71 GM Pos X 36 36 0 - 60 OSD X position for gemstar.
72 GM Pos Y 13 13 0 - 36 OSD Y position for gemstar.
73 GM Siz X 110 110 0 - 152 OSD X Size for gemstar.
74 GM Siz Y 100 100 0 - 233 OSD Y Size for gemstar.
75 Mut Brt 20 20 0 - 63 Level Brightness when mute.
76 Mut Con 20 20 0 - 63 Level Contrast when mute.
77 GMVSize 30 30 0 - 63 GMVSize.

DD

AA

TT

D

A

T

DD

AA

TT

VV

ALUEALUE

V

ALUE

VV

ALUEALUE

AA

A

AA

ON-SETON-SET

ON-SET

ON-SETON-SET
VV

ALUEALUE

V

ALUE

VV

ALUEALUE

VV

ALUEALUE

V

ALUE

VV

ALUEALUE

RANGERANGE

RANGE

RANGERANGE

NONO

NO

NONO

TESTES

TES

TESTES

ZENITH MODEL B27B40Z

ZENITH MODEL B27B40ZZENITH MODEL B27B40Z

ZENITH MODEL B27B40ZZENITH MODEL B27B40Z

SET 4703 PSET 4703 P

SET 4703 P

SET 4703 PSET 4703 P

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SET 4703 SET 4703

SET 4703

SET 4703 SET 4703

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