Motorola 51M1U Schematic

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Product Information:
Model:51M1U
Manufacturer:Motorola (Galvin)
Description:HS-283

Schematics Content:

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Page 1:

PAGE 22-116 MOTOROLA
MODELS S1l"llU,
GENERAL INFORMATION
TYPE - Three-power (Ac/DC, Battery) portable radio re-
ceiver. Four miniature type tubes and a selenium
rectifier are used in a superheterodyne circuit.
Model Color
51M1 U Green
SIMZU Maroon
TUNING RANGE ~ 535 to 1620 Kc IF - 455 Kc
TUBE COMPLEMENT - Type Function
lR5 Converter
IU4 IF Amplifier
384 Power Amplifier
Rectifier Selenium type -for
AC/DC operation
POWER SUPPLY - Operates fromll7V AC/DC (15 watts)
or from the following batteries:
Z - l-l/ZV fltlllllghi cells (Evereedy
I - 67-l/ZV "B" battery (Eveready #467
OPERATING IISTIUCTIOIS
TO OPEN FRONT COVER. The front cover is opened by
pushing upward on the "M" bar located in the center oi the
cover. The receiver is automatically turned on when the
front cover is opened and raised to a vertical position.
TO OPEN BACK COVER, The back cover may be opened by
gently pulling it at the top. When closing the cover, be
careful not to pinch the power line cord or other leads be -
tween the cover and the cabinet.
'll7 VOLT AC OR DC OPERATION. The power cord is lo-
cated inside the cabinet and may be reached by opening the
back cover. Pass the line cord through the slot on the side
of the receiver, and plug it intoany ll? volt AC or DC power
outlet. If the receiver does not operate from DC power,
reverse the plug in the power outlet. When operating from
AC power, reception may sometimes be improved by re-
versing the power plug in the outlet. lt is not necessary
that batteriesbe installed ifthe receiver is to be operated
only from house power lines.
BATTERY OPERATION. Open the back cover and install
the batteries, following the instructions on the label inside
the back saver- (of see Figure x). insert the une cord plug
into the receptacle on the chassis, or the receiver will not
play (rom batteries. ll the receiver is to be operated for a
long period of time from 117 volts AC or DC, or is to be
placed in storage. remove the batteries and store them in a
cool place. IMPORTANT: Never leave low or run-down
batteries in the receiver, as they will leak orswell and
damage it.
TUNING CONTROL. Stations are tuned in with the right-
hand lmob. The markings around the tuning knob may be
read in kilocycles by adding one zero to the figures.
VOLUME CONTROL.. The left-hand knob controls volume.
TO TURN OFF. Closing the front cover will automatically
turn off the receiver.
ANTENNA. A loop antenna is built into the front cover.
Because of the slightly directional characteristics of the
loop antenna, reception from some stations may be im-
proved by rotating the entire receiver. ln extremely noisy
locations, rotate the receiver until minimum noise and max-
imum signal pick~up are obtained. ,
BATTERY REPLACEMENT. lf low volume or fuzzy tone
is noticed when operating from batteries, replace are :lane
light cells. Normally, the 67-l/ZV "B" battery will last lor
3 or 4 changes of the flashlight cells. The condition of the
batteries will not affect the operation ol the receiver from
ll? volts AC or DC. Complete battery replacement instruc-
tions will be found inside the cabinet backcover (or see Fig-
(C)Joh.n F. Rider

Page 2:

MOTOROLA PAGE 22-ll
MODELS ?lMlU ,
WHEN PLAVING FROM MUSE CURRENY PASS
LINE CORD THROUGH SLOT' IN CABINET
FOR BITTERY OPERATION PLUG THE
LINE CORD lNYO NECEPIADLE ON
7 OMAS$|S GR SET WILL NUI PLAY
CHASSIS MTG
SCREW
at use :vsnnuv asv
ok NAV 0 VAC 4561
' ' ? TT?RIE?' USE TWO L5 VOLT FLASHLPGHY CELL
COIL LINE CORK: HERE /1 \
WNEN NoY In use
` FIGURE 1. BATTERY INSTALLATION
on Anv s\zE'o' FLASHLIGHT CELL "
|Ns1'A\.\. 'A' BAUERES $0 SPRING coN'rACYs
BOTTOM or BAHERIES.
NOTE: The receiver may be operated either from bat>> 4. Turn the receiver volume control to maximum.
teries or (rom the commercial power lines during IUEU'
ment. If AC power is used, it is recommended that an iso-
lation transformer be placed between the power line and the
receiver. If an isolation transformer is not available, con-
nect the low side ol the signal generator to B- through a .1
diode transformers.
15. As stages are brought into alignment, reduce the signa
1. Connect a low range output meter across the speaker
voice coil.
irnately .05 watt (. 05 watt = .40 volts on the output meter
to avoid overloading the receiver.
Z. Connect the low side of the signal generator to B-.
7. See Figure Z for adjusting locations and the following
3. Set the signal generator for 400 cycle, 30% modulation. chart for procedure.
ALIGNMENT CHART
5. Use a small libre screwdriver for aligning the IF and
generator input to keep the output of the receiver at approx-
DUMMY GENERATOR GENERATOR GANG
STEP ANTENNA CONNECTION FREQUENCY SETTING ADJUST REMARKS
IF ALIGNMENT
l. . l .ml Grid of conv 455 Kc Fully I, Z Br 3 Adjust for maximum.
(pin 6, lR5) open (IF cores)
RF ALIGNMENT
2. .1 mf Grid of Conv 1620 Kc Fuuy 4 (Osc) Adjust for maximum.
(pin 6, ms) open
3. - -- Install chassis in cabinet. leaving
output meter connected en speaker.
4. Radiation 1400 Kc Tune for 5 (Ant) Adjust [or maximurn. Trimmer i
loop* max. reached through hole under plug
button on side of cabinet.
U Connect generator output across 5" diameter, 5 turn loop and couple inductively to receiver loop. Keep loops at 1255i
(C)John F. Rider

Page 3:

PAGE 22-118 MOTOROLA
SERVICE
The chassis of this receiver is isolated from the AC
power une circuit by a capacitor-choke assembly to enmi-
nate the shock hazard when handling the receiver. How-
ever, as an additional precaution when aligning or servicing
the receiver from AC, an isolation transformer should be
inserted between the power line and the chassis.
The tubes are exposed when the rear cover is opened.
It is not necessary to remove the chassis to replace tubes.
LINE GORI
x. Pull off me two control knobs on the front of the eabinet.
2. Open the rear cover and remove the batteries.
3. Remove the two Phillips head screws holding the chassis
to the cabinet ("A" - "A" in Figure 1),
4. Slide the chassis out of the cabinet.
5. Disconnect the two leads from the chassis to the loop
antenna hinges.
BATTERY
FIGURE 3.
REAR VIEW OF RECEIVER
(C)Joh.n F. Rider

Page 4:

MOTOROLA PAGE 22-119
MODELS ?lNlU,
FIGURE 4. TOP VIEW OF CHASSIS
R2 QT T gy , L _ U, >>` "f"?f*"""".>'~ ~f1l~'3 1 , *"?"'"`"_
' AF AMP _ = ~ ,
'A' BATTERY 'a' aATTER~r W BA1-TEM
RETAINER TsRM|~A|_ srmw RETAINER
FIGURE 5. BOTTOM! VIEW OF CHASSIS
(C)John F. Rider

Page 5:

PAGE 22-120 MOTOROLA
MODELS 5 1M1U,
|?:?_; 5 fig O za ?
,e 4 ? _ Jog s""? L. 3 2 " g
(C)John F. Rider

Page 6:

MOTOROLA PAGE 22 '|2'|
MODELS 5lNlU,
/ @ MEG HU
I / COM connscnous conwzcnous mo 52%
I c 6 n U \ Q c cv fl/gk, ago
* YRIMMERS FRED RANGE 5554520 KC.
L2 on saws
ALL nzsmnns mmwzn |~ om. mf; gp ng Em ern mn "?""
KI ONE YNUUSANU UOOGI OHMS. : : 220K
VOLYAGE NEHSUWEIIENTS MADE WITH I ssg an
a n\zn%J:Emzn1 uno: mm GANG _,M $3 ?;agz;:a mn M 1 . 2
FIGURE 7 . SCHEMATIC DIAGRAM OF CHASSIS US ING MULTIPLE CERAMIC CAPACITOR-RESISTOR PLATE

Page 7:

PAGE 22-122 MOTOROLA
MODELS 5ll"IlU,
RHPLACEHBH1' PARTS LIST
l NOTE: When ordering parts, sperify model number of set 1n addition to part nurnber and description oi part.
Ref. Part
_ Ref. Part
Egi- 52225; 95225323322 No. Number Description
CHASSIS PARTS - ELECTRICAL Resistors
C-1 l9K692007 Variable 2-gang..........
0_2 21K481377 Ceramici' 500 mmf 5o0v_____ Note: All resistors are insplitgd, carbon type
C 5 K 11-3 1714692009 Wire wound; 2150 5% 1011;
Ceramic, disc type: 10,000
Ceramic, disc type: 100 mmf
Ceramic, disc type:
Ceramic, disc type: 5000
Ceramic, disc type: 10,000
Choke Capacitor
I Rectifier
(C)John F. Rider
Choke & .05 mf 200V paper
Selenium Rectifier: half-
Antenna Loop & Front Cover
Assembly: complete; green
Antenna Loop, Panel & Hinge
Assembly: less front cover;
green plastic (5lMlU)......
Antenna Loop & Panel Assem-
bly: less hinges: green
plastic (5lHlU)............
Antenna Loop & Front Cover
Assembly: complete: maroon
Plastic (51M2U).. ......
Antenna Loop, Panel 0 Hinge
Assembly: less front cover;
maroon plastic (51M2U) .... .
Antenna Loop & Panel Assem-
bly: less hinges; maroon
plastic (5lM2U) .... _ .......
Oscillator Coil (yellow code)
10 meg 20% QW..."
11-9 6122118 9.3 meg 20% iw ......
R-10 l8A69l993 Volume control: 1 meg...
11-11 6112109 10 meg 20% iw. . . . ..... _
11-16 61125.22 4.7 meg 20% 111. ..
11-17 SR6004 1 meg 20% lvl. . . _ .
R-18 6R2llB 3.3 meg 20% ?W....
Switches
Rotary Switch, 5 PDT (AC/DC-
Battery selector). . . . . . . . .
Slide Switch (on-off)......
Transformers
complete with capacitors..
Diode Transformer, 455 Kc:
complete with capacitor...
Output transformer........
CHASSIS PARTS - IECHANICAL
Bushing, insulator: fibre (chassis
mtg screw insu1ators),,, ._,,, ,_
Bushing, strain relief: line cord
(use with 43K692013). ....... . .... .
Clip, electrolytic mtg ________,_
Clip, IF transformer mtg..,..,,,
Cord, line: with plug; 6 ft long..
Lug, soldering: battery contact
(in "A" battery retainer) .,.., _
Receptacle, loop (on loop leads)
Retainer, strain relief (on line
Shield, back (on rear of chassis)
Shield heat (around R-3). .,.__, _
Shield, switch (over AC/DC-Battery
Spring, battery contact (in "A"
battery retainer) ..,_,_,__ ,

Page 8:

MOTOROLA PAGE 22-123
MODELS 51MlU,
Pitt Plrt
I Number Description Number Description
3lK4708B0 Strip, "B" battery terminal: with 35400335 5,nrew_ sheet metal, gg X 5/15;
leads.........................-... Phillips flat head; blk nkl
3lK37504 Strip , terminal: 1 insulated lug, (mounts 10?F to fron; Cover) _ _ _ N
xl mtg............................ 35490739 screw, sheet metal; #4 x Q PKZ;
3lK470746 Strip, terminal: 3 lnsulated lugs, phillips hinder head (chassis mtg)
4K470939 Washer , fibre (R-3 mtg). . - 352995 Screw, machine: 5-40 x 5/16 pl hex
head; cad pl (handle mtg)....
4lA470909 Spring, door latch (inside front
IODEL 51l1U CABINET PARTS GOVEURl')....~.............-......
4lK692167 Spring, handle (inside plastic han-
7A600092 Bracket, escutcheon support (cab- dlel---~---~--~~-~-------->>--~-~--
inet front Snppnrg) _ _ _ _ _ _ _ _ _ _ _ _ _ _ 4lK60l7l2 Spring, rear cover latch. . . . . . . .
38K692()50 B\_\tt?n_ plug; gy-een gxnisn (limp 42A692l89 Strap, door latch retainer (inside
trimmer nd] now cove,-)___________ front cover) ......................
13601312 Cabinet, complete; less nanny," 46A69215l Stud, latch retainer (front cover
S,-i11e and antenna 10?F and front latch on grille) . . . . . . . . . . . . . . . . _ .
cover assembly; green p1a?\;1?;_ _ _ _ _ 46K690079 Stud, trimount: blk nkl (on loop
42A6ooo94 Clip, grllle retnlner (holds grille panel - for Operating Gu-Gff
55A692058 Cover , handle mtg (over ends of
13D69l949 Escutcheon , dial In volume (on front
55A27113 Foot _ cabinet bottom: felt _ _ _ _ _ IIODEIL. 5lll2U CABINET PARTS-Same as' Model 5lllU Except:
lX692l62 Front Cover Assembly: complete;
less 1??n_ green nlnstim _ _ _ _ _ _ _ _ _ 3BK6\J0l06 Button, plug: maroon finish (loop
lX692l58 orllle Assembly: complete wlcn trimmer "di h?\? ??Ve')--~-~-->>---
ennntcneom green nlastic _ _ _ _ _ _ _ _ lX60 1816 Cabinet: complete , less handle ,
55K692l66 Handle, narrylng: green plantle; grille """ ""'E""" 1??P "?d f'?"f
lens nn_.ing_______________________ cover assembly; maroon plasticu..
55C692202 Hinge_ front cover, con_n1ete_ 1eft_ l3K61J0956 Escutcheon, dial & volume (on front
55K600087 Hinge, front cover: complete; right 1X6?0131 Fr?"t C?V?' AsSe"b1Y' ??mP1?'?r
band.............................. less 1??P5 '""`??" P1"S"?-------
55130198 Hinge _ near cover _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ lXG00l28 Grille Assembly: complete with
3613691899 Knob, control: green plastic. . . . . . escutcheolu '"r??" p1asti?' ' ' ' j ' ' '
lX692l63 Latch and Plate Assembly (lnslne 55K60?1?7 """"1?~ ?affY*"EUR= -"='??" P1"S*1?P
front cover)______________________ less spr1ng.......................
438406 Lock_,nsner_ int: #2 (1?nn)_ _ _ 36K600105 Knob, control: maroon plastic, . . . .
457695 L?Ck'__sner_ int: #5 (hnndle nts) 5S28IZ7 Rivet: .088 x 5/32; stl; statuary
29R5399 Lug, soldering (under front hinge, 5528328 Rivet: 388 X 3/165 Stl; Statuary
for loan Connectinn) _ _ _ _ _ _ _ _ _ bronze (front cover hinge mtg)
l3B69l90l ledalllon (on front cover)......... """""""'?""""""'
2BA692l98 Pin, loop connector (on front hinge) 38400336 s?"e">> sheet "'et"1: *2 X 5/165
64K6016l8 Plate, handle mtg (under handle mtg _ ("?""*S 1??P ?? f'?"" ??"?')-~-
covers)__________________ ______ 46K6B0035 Stud, trlmount: statuary bronze
(rear cover hinges latch spring off avlltch) . . . . . . . . . . . . . . . . . . . .
(front binge utg).............
Linn rnnnd head (mounts front or 508610070 Speaker: CQ" PM; 3.2 ohm VC
hinges to cablnet).............
Rider

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