Zenith 4g903

Page 1

PART NO. REF.NO.

1;.1954
26.420
46.785
51-1490
51-1493
57-1513
51-1514
76-540
00-309
93.913
loo-3:
3-15430
3.19440
5-1544:
5-16016

95-1)
95-1133
8.15629

23-3
22-102
22.326
22.492
22-826
22-021
11-339
22-1386
22.1669
22-1741

22-4775
21-2032

32-2108

63-1719
63-116!
63-1171
63-1778
63-1841
6128

ARM! W1; common

0' SWIM ON PULLEYS

11mm [50'

LA. mu.

sun It mt
alumna .0me

DIN. CORD DEW!

Tl
T2
L2

09
CS
CH

(34

CS

Cl?
010

08
€13.14
)5 I: 16
C12

C1

C1

R 15
R3
R4
R7
R6
R1

nirvana or ammo /

0n receivers using Tuning Gong #223032, Dial String Assem-
blies #845440 (short) anti #845441 (long) must be used.

D8808]?! ION

Tuning slut: sucks:

4?

8:33;
95:

room If
3- 1:6}: ;

DIAL. ASSMLY

Dial Soolo
7min. h Vol. Control Knob (Z Usod)
Dmblom Plato
Trim PIA

Emblem Ploto {Y Model only)
Trim Ploto (Y Modal only)
Toning sun
Biol Cord Tension Spring (3 Uood)

Fol! Nook: (Used behind Pointer Anon.)

Running Rio. (Used an 76-5!)
Poiator I: Policy Assom.
Dial Cord Auom. (Short)
01-! CON! Anon. {Lou-l
Din! Cord Anon. (Long)

COILS Ix (SHORES

lot. I. I. Trouformor
2nd. I. F.

Doc. Coll Alum.

CONDENSERS

.Ol m. Coumic Disc.)
320 Mm. (Molded Nico.)

.003 Mid.
.002 "
.01 "

.1 I.
.05 I.
.02
100 mid.

Four Socuon Bloctrolytic

.0"? Mid. (Molded) {or 2.2-1914)

Too Section Fling
Two Sutton 0on3
RESISTORS

21' Ohm
210 I!
070 "
630 "
22K "

Maw
1/21!
1/20;
I):
Maw

10'}.
107.
10%
Ni
10%

100:: mm I/zw "

Ins.
Ins .
Ins .
has .
In: .

500V
500V
400V
600V
2 00V
200V
200V
200V
500V

DOV

63-!9l2
63-1933
63-1940
63-1954
65-1961
63-1999
63-1010
63.2013

-104
12.1553
144103

H -l [031'

15-51

19-99

19-185
ZI-QSI
ZodSZ
3Q-495
49-658

54-30
54-34

54.139
51-16?
«-132

54-283
54-284
57 4480
57 cl)!
57-1494
61-?!
61-136
64-288
64-290
64-303
?8-2M
?8-543

m... m .. "r'" m ow. CABLE DRAWING

PART NO. REFJIO.

R12
214
313
R2
R11
28
9.9.10
115

SP-l

WM

DIAL CABLE onAw'uio

DEM.

IWNIWMOWDW

virus or my .

On receivers using Tuning Gong #22-2108. Dial String Asses-n-

blies #8-15440 (sho
PARTS LIST

DESCRIPTION

1! ESISTORS

lMchhm l/zw 2.01- Ins.
3.3mgonm1/zw 2.0% In.

4.7 " " 1/2.?! 2.07.

10 " " 239.20%

15 " " 1/2.»: 207. "

10 Ohm SW 10% (Zipohm) Ins. {or 63-3014)
Two Socuon Condohm

Volnmo Control

____MW mums

Lino Core! I: Plug

Ghouls Mt... Brld. (Z Used)

Cobb" {or 46903 (Us: S-lSZ?)

Cobb [or £090?! (Use 5-1563

Coblg Soda Cop l: Insulator

Coll Mtg. Clip

Spook" Bottle Rot-inning Clip! Una)

Front Door

Ora-Of! Switch Cove:

Erect Door ('1 Model only)

4" PM. Spookor

203-653 Com I: Voice Coll

206-658 Output Trout.

00-32 X S/lb X 7/M"HuflotsuolN.P.

{6.31 x 1/ " x 3/32 HuNut - StoolN.P.
{Used on Rocutior)

l3/O-32 x 9/16" Polont-Typo 9!! God. Pl.

[Used on Vol. Control)
06-31 2 5/16 Polout Cad- Pl. (2 Used on
I. I". Tron.)

Sofia; Nut-Cod. Pl. (3 Hood on Diol Sale
I. Poiator)

Spring Nut. Block Oxide (3 Us)

Wovomosnot Lood Retaining NM (2 Uood)

Chou!- Bottom Plate (Maul)

Latch Plot. (Behind Latch}

Cobinot Rolnforcing Plate

Idler Pulloy (6 Used}

1610: Pulley (Block)

Shoulder Rivet (2 Used on 8-1559!)

WY Rivot {I Uood on 61-?!)

Shoulder Rivot [I Used on 5-1543!)

moot. cm. Socket

amm- cm. socket (4. cannot)

PA RT NO.

18-182
18-806
78-807
80-699
83-1600
83-1610
85-450
85-461
9c-113
113-?61

llS-ll
113-13
111-159

114-311
114-319

167 -l 56
156-37
156-38
156-39
166-44
192-1
199-5

{99-116
202-689
212-5

8-1542?
545433

3-15434

5-15438
3-15473

S-lfifiS
5-1554?
5-15595
5-15631
S-l5632
5-1563}

REFJIO.

31
53

W1

rt) and #346106 (long) must be used.

DESCRIPTION

MISCELLANEOUS

Miniolaro Tub. Socket
Mauro Tube 306%
Minioturo Tube Sockot (3 Used)
lunch Spring
W1. Strip ($10M)
Wovomognot Rowinfing Strip (3 Used)
Power Change-Over Switch
On-Oft Switch
Hoodlo Meg. Bushing (2 {nod}
'2 X l/ " Phil]. 2.3.5.7. Typo 2 MNJ.
(Z Used on Emblom Ploto)
I643 3 5/16 Hex. Rd. Slonod M.8. Stool
Cod. Pl. Shakcprt. (a Uood on 85 .4 SO)
".32 x 5/16 Hex lid. 81. .3. Stool. Cod.
Pl. Int. Shokeprl. Lock (3 Used 0138.] 5633)
#6 x 1/4 Hex Rd. 8.1. Scrow Cod. Pl.
{4 Usod on 8-1543?)
36-32 x 1" Heat Ha. Slottod MS. Stool N.P.
(I Used to Mt. Retail:
-32 X 11/16" Hex Ho. Slouod M.S. Stool
Cod. Pl. (2 Uaod to M. Hmdlo)
Spook-r Mtg. Spocor
Door Lou-.11
Root Covor Catch (2 (bod-Block)
Door Luck (1' Model only)
Rubber Bunpcr {Spookor & Gong)
Diol Gloss
"loflblo Hood]. Show (With Cordbool'd
Strip.)
Popor sloovo (030:! on Wovomogoot Load)
lustrudloo Book
selenium Rectifier (or 211.3)
Cabin Front 8: Hinge Anon-u.
Support Britt. In Inter Polloy Auom.
(Gong I: Door)
Wowmosnot Winding anon.
Bonn-y Coblo & Sockot Atom.
Spookor Baffle I: Grillo Cloth Alum.
(110-1 37)
Clbiml Rn: Cor-r Atom.
Mo End Pinto: Anon. (3 Usod)
Britt. I: Idler Pulley Assam. (Lower)
Comm Fran: lungoAuom. {YMoool only)
Coblnot Root Cow: Also-m: (1' Model only)
Hondlo End Ptocos Assom. Y Model on! )

dHAN

mNBIGauvmawnoofl

:E'IIHQBV
ongH PIA 8110181H "A 'JeA 'paN

Page 2

TO THE SERVICE MAN:

The 4F40 chassis is an AC, DC or battery operated super-
heterodyne. The chassis is isolated iron: the DC circuit,
and all measurements met he made from a cm nega-
tive point. The most convenient place to reach this nega-
tive point is the terminal strip to which C17 is connected.
When the change over Switch 51 is in AC position, the DC
resistance {rem chassis to any circuit must be almost in-
finite. If any circuit becanos grounded a hum Will result.
Microphonic tubes will cause audio howl. Check the 1115
and 155.

The WW is connected to the chassis by two wires
that pass through the hollow dial pivots. If the R.F. be-
comes week or dead. check the D.C. resistance of the
wavunagnet. This D.C. resistance should be approximate-
ly .9 ohm. If it is Open check the wavemagnet.

3 IF Alignment: Remove the chassis from the cabinet and
arrange the units so that the wavemagnet can be connected.
All the connections and adjustments can he mace Item the
top of the chassis. Contact a signal generator, through a
.1 mid. dummy antenna. to the converter grid ma 8 -
(common return). Connect an output meter across the
voice mile! the Speaker (two lugs provided). Set the sig-
nal generator to 455 Kc. and adjust L3. L4. L5 and L6 for
maximum indication on the outtpm meter. Always keep the
signal wtpot from the generator just high enough to get an

I indication, otherwise excessive loading my result.

RF Alignment: Connect a two turn loop across the leads
of the signal generator. loosely couple this loop to the
wovemagnet. Set the signal generator and the dial point-
er of the receiver to 1600 Kc. and adjust CS oscillator
trio-one: to resonance. Set the signal generator and dial
pointer to 1400 and adjust C2 antenna trimmer to reson-
ance. These trimmers are on the top of gang condenser.
Check operation and re-install set in cabinet. Tune too
weak station near 1400 Kc. or use background noise and
readjust antenna trimmer for maximum sensitivity.

mun act-we Ml!
sou mm mm-

L$ alum x.
L6 socrorH

m mm.
455.

ON-o" switch!

6

TUBEJRIMMER lOCA'I'ION

351' If. TRANS.
65 KC.

L... @

®

lilo

-_.-:Hv - _ v-W
I .
e ' _ .

L3 FRI. 00710
LA SECTO?

VOLUH CD). TROL

TUNING

ALIGNMENT PROCEDURE

C2 ANY. TRIMR

C3 05C. TRIM]?!

OPERA- CONNECT DUMMY ENPUT 510. SET
non oschuvron 'ro ANTENNA FREQUENCY BAND om. To TRM'ERS 9URPOSE
!III-I-I- 1t
I Converter 1.3.1. LF.
Grid. .1 MM 455 Kc. BC 600 Kc. 58: 6 Alignment
0
Two turns k
2 loosoly 03:. Set
coupled to I600 Kc. BC 1600 Kc. Trim. Oscillator
Wavema net
..._L_ 3 C3 to scale
TWO tunes
3 loosely Ant.
Coupled to 3400 Kc. BC I400 Kc. Trim. Align
Wavmgnet c2 Wavemagnet
-

0+:

my 11:)

'IHCIOH
1 V

6