Elenco Electronics XK-550K Assembly And Instruction Manual

DIGITAL / ANALOG TRAINER

MODEL XK-550K

A COMPLETE MINI-LAB FOR BUILDING,TESTING

AND PROTOTYPING ANALOG AND DIGITAL CIRCUITS

Elenco Electronics, Inc.

Copyright © 1995 Elenco Electronics, Inc. Revised 1999 REV-F 753550K

Tools and meter shown not included.

Assembly & Instruction Manual

-1-

PS-550-B

XK-550K POWER SUPPLY KIT (PS-550-B) PARTS LIST

RESISTORS

QTY SYMBOL VALUE DESCRIPTION PART #

r 2 R1, R2 120Ω 5% 1/4W (brown-red-brown-gold) 131200
r 1 VR3 1KΩ Pot PC MNT 192412
r 2 VR1, VR2 2KΩ Pot PC MNT 192421
r 1 VR4 100KΩ Pot PC MNT 192612

CAPACITORS

QTY SYMBOL VALUE DESCRIPTION PART #

r 5 C6 - C10 .1µF 100V Mylar 251017
r 7 C11 - C17 100µF Electrolytic 281045
r 4 C1, C2, C4, C5 1000µF 35V Electrolytic 291096
r 1 C3 2200µF 25V Electrolytic 292225

SEMICONDUCTORS

QTY SYMBOL DESCRIPTION PART #

r 15 D1 - D15 1N4001 Diode 314001
r 1 U1 LM317 Integrated Circuit 330317
r 1 U5 LM337 Integrated Circuit 330337
r 1 U3 LM7805 Integrated Circuit 337805
r 1 U2 LM7812 Integrated Circuit 337812
r 1 U4 LM7912 Integrated Circuit 337912

MISCELLANEOUS

QTY DESCRIPTION PART #

r 1 Transformer 44K500
r 1 PC Board 514550
r 1 Fuse 1.25A 530125
r 1 Switch Illuminated 541204
r 2 Connector 3-pin 591032
r 1 Connector 5-pin 591052
r 1 Bracket 613003
r 4 Bracket L 4-40 tap 613008
r 1 Panel Top 614102
r 1 Panel Side Right 614551
r 1 Panel Side Left 614554
r 4 Knob 622009
r 1 Case 623002
r 1 Bushing 624009
r 1 Spacer Nylon 7/16” x 3/16” Tap 624013
r 1 Connector Receptacle 626020
r 1 Connector Plug 626021
r 1 Cord Retainer 628003
r 9 Screw 4-40 x 1/4” Slotted 641430
r 1 Screw 4-40 x 1/4” Phillips 641431
r 8 Screw 6-32 x 5/16” Slotted 641641
r 2 Screw 8-32 x 3/8” Phillips 641840
r 2 Screw #4 x 1/4” Phillips AB 642430
r 4 Screw #8 x 1/2” Phillips AB 642862
r 4 Screw #6 x 3/8” Phillips Thrd Ct 643652

QTY DESCRIPTION PART #

r 4 Nut 7mm 644101
r 8 Nut 6-32 644601
r 2 Nut 8-32 644800
r 4 Washer 8mm x 14mm (Pot) 645101
r 4 Washer Fiber 645404
r 2 Lockwasher #6 INT 646600
r 2 Lockwasher #8 EXT 646828
r 1 Lug Solder #8 661002
r 1 Fuse Holder 663000
r 4 Bredblox 4-pin 665204
r 2 Terminal Male Cr imp 666010
r 2 Terminal Female Crimp 666011
r 1 Label (XK-550K) 723501
r 1 Manual 753550K
r 5 Insulator Mica 780002
r 5 Insulator Washer 780101
r 1 Silicon Grease 790004
r 6” Wire #20 Red Stranded 813210
r 2.5’ Wire #22 Bare Wire 845000
r 1 Line Cord 862105
r 2” Shrink T ubing 3/16” 890120
r 1” Shrink T ubing 1/4” 890701
r 2” Shrink T ubing 1/2” 891101
r 2” Shrink T ubing 3/4” 899110
r 1 Solder Tube 9ST4A

Screw Identification

Phillips AB Screw 4-40 / #6 Thread Cutting Screw Standard Screw

(Type 23)

Flat Head Screw

-2-

PARTS VERIFICA TION

Before beginning the assembly process, first familiarize yourself with the components and this instruction book.
Ver ify that all par ts are present. This is done best by checking off each item in the parts list.

RESISTORS CAPACITORS

Trim Pot

Pot

Discap Mylar

Electrolytic (Lytic)

(Radial)

IC

SEMICONDUCTORS

INTEGRATED CIRCUIT

Diode

Transistor

IDENTIFYING CAPACITOR VALUES

Capacitors will be identified by their capacitance value in pF (picofarads) or µF (microfarads). Most capacitors
will have their actual v alue printed on them. Some capacitors may hav e their value printed in the following man­ner.

Second Digit

First Digit

Multiplier
Tolerance

The above value is 10 x 1,000 = 10,000pF or .01µF
The letter K indicates a tolerance of +

10%

The letter J indicates a tolerance of +5%

For the No. 01234589
Multiply By 1 10 100 1K 10K 100K .01 0.1

Multiplier

Note: The letter “R” may be used at times to
signify a decimal point; as in 3R3 = 3.3

IDENTIFYING RESISTOR VALUES

Use the following information as a guide in properly identifying the value of resistors.

BAND 1

1st Digit

Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9

BAND 2

2nd Digit

Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9

Multiplier

Color Multiplier
Black 1
Brown 10
Red 100
Orange 1,000
Yellow 10,000
Green 100,000
Blue 1,000,000
Silver 0.01
Gold 0.1

Resistance

Tolerance

Color Tolerance
Silver +10%
Gold +

5%

Brown +

1%

Red +

2%

Orange +

3%

Green +

.5%
Blue +.25%
Violet +.1%

Bands

1 2

Multiplier

Tolerance

-3-

CONSTRUCTION

Introduction

Assembly of your XK-550 Digital/Analog Trainer Kit will prove to be an exciting project and give you much satisfaction and personal
achievement. If you have experience in soldering and wiring techniques, then you should have no problem with the assembly of this kit.
Care must be given to identifying the proper components and in good soldering habits. Above all, take your time and follow these easy
step-by-step instructions. Remember, “An ounce of prevention is worth a pound of cure”. Avoid making mistakes and no problems will
occur.

CAUTION: WEAR SAFETY GLASSES WHEN ASSEMBLING THIS KIT.
Assemble Components

In all of the following assembly steps , the components must be installed on the top side of the PC board unless otherwise indic ated. The
top legend shows where each component goes. The leads pass through the corresponding holes and the board is turned to solder the
component leads on the foil side. Solder immediately unless the pad is adjacent to another hole which will interfere with the placement
of the other component. Cut excessive leads with a diagonal cutter. Then, place a check mark in the box provided next to each step to
indicate that the step is completed. Be sure to save the extra leads for use as jumper wires if needed.

Soldering

The most important factor in assembling your digital / analog trainer is good soldering techniques. Using the proper soldering iron is of
prime importance. A small pencil type soldering iron of 25 - 40 watts is recommended.The tip of the iron must be kept clean at all
times and well tinned. Many areas on the PC board are close together and care must be given not to for m solder shor ts. Size and
care of the tip will eliminate problems.

For a good soldering job, the areas being soldered must be heated sufficiently so that the solder flows freely. Apply the solder simulta­neously to the component lead and the component pad on the PC board so that good solder flow will occur. Be sure that the lead
extends through the solder smoothly indicating a good solder joint. Use only rosin core solder of 60/40 alloy.
DO NOT USE ACID CORE SOLDER! Do not blob the solder over the lead because this can result in a cold solder joint.

1. Solder all components from
the copper foil side only.
Push the soldering iron tip
against both the lead and the
circuit board foil.

Component Lead

Soldering Iron

Circuit Board

Foil

2. First apply a small amount of
solder to the iron tip. This
allows the heat to leave the
iron and onto the foil.
Immediately apply solder to
the opposite side of the con­nection, away from the iron.
Allow the heated component
and the circuit foil to melt the
solder.

Solder

Soldering Iron

Foil

Example 1

Poor solder connections occur
when the lead is not heated
sufficiently. The solder will not
flow onto the lead as shown.T o
correct. reheat the connection
and, if necessary , apply a small
amount of additional solder to
obtain a good connection.

Solder does not flow onto the
lead. A hard rosin bead sur­rounds and insulates the con­nection.

Poor solder
connection

Mount Part

Soldering iron posi­tioned incorrectly.

Example 2

A solder bridge occurs when
solder runs between circuit
paths and creates a short cir­cuit. This is usually caused by
using too much solder. To cor­rect this, simply drag your sol­dering iron across the solder
bridge as shown.

4. Here is what a good solder
connection looks like. Cut
off excess leads.

3. Allow the solder to flow
around the connection.
Then, remove the solder and
the iron and let the connec­tion cool. The solder should
have flowed smoothly and
not lump around the wire
lead.

Solder

Soldering Iron

Foil

Bend Leads to Hold Part Solder and Cut Off Leads

Foil Side

Rx - 100Ω 5% 1/4W Resistor

(brown-black-brown-gold)

þ

-4-

INTRODUCTION

The XK-550K Digital/Analog Trainer is divided into four separate kits: BB-550-A, PS-550-B, AN-550-C and DG­550D. Each bag of parts is clearly identified. Open only the kit called for in your procedure. DO NOT open any
other bag at this time. The first kit is the BB-550-A which contains only the bredboard. The bredboard will be
assembled to the front panel of the trainer during the assembly of the PS-550-B Power Supply. Read your
instructions carefully.

POWER SUPPLY

The XK-550K has five built-in power supplies which will satisfy most design needs. This includes two variable
power supplies giving up to +20 volts and -20 volts at .5 amp. Below 15V, the current available is 1 amp. Three
fixed power supplies give you +12VDC, -12VDC or +5VDC at 1 amp each. These fixed voltages are the most
commonly used voltages for design work. All supplies are regulated to within 150mV. This means that you can
increase the current draw from no load to .5 amp and the voltage will change less than 150mV. All supplies are
also short circuit protected by using integrated circuit regulator devices.

ANALOG TRAINER SECTION FUNCTION GENERATOR

The analog trainer contains a complete function generator capable of producing sine, square and triangle wa v e­forms. The frequency of the generator is continuously variable from one hertz to over 100,000 hertz in five
steps. A fine tuning control makes the selection of any frequency easy. The output voltage amplitude is vari­able between 0 to 15Vpp. The output impedance is approximately 330 ohms.

DIGIT AL TRAINER SECTION

The digital trainer has the necessary functions to do your digital experiments. They consist of a clock genera­tor, two no-bounce switches, eight LED indicator lamps and eight data switches.

POWER SUPPLY SPECIFICATIONS

Power Supplies:

• +1.25V to 20VDC @ .5 amp (1.25V to 15V @ 1 amp).

• -1.25 to -20VDC @ .5 amp (-1.25V to -15V @ 1 amp).

• +12V +

5% @ 1 amp.

• -12V +5% @ 1 amp.

• +5V +5% @ 1 amp.

• 30VAC center tapped @ 1 amp.

• Load regulation - all DC supplies less than .2V no load to .5A.

• Line regulation - all DC supplies less than .2V 105 to 135V.

• Hum and ripple - all DC supplies less than .01V RMS.

• Short protection - all DC supplies-inter nal IC ther mal cutoff.

• Fuse 1.25A 250V.

Variable Resistance (undedicated):

• 1KΩ Potentiometer

• 100KΩ Potentiometer

USERS DESCRIPTION OF FRONT PANEL CONTROLS

1) On/Off Switch - Allows power to be applied to all outputs. Switch will
light when on.

2) Fuse Holder - Easy access for replacement of 1.25A fuse.

3) Power Output Terminals - This provides 30VAC center tapped at
15VAC; also provides output terminal for positive and negative
variable voltages.

4) Variable Positive Voltage Control - Varies positive voltage from 1.25
to 20V at indicated output connector pin.

5) Variable Negative Voltage Control - Varies negative voltage from

-1.25V to -20V at indicated output connector pin.

6) Output terminals for 1K and 100K undedicated potentiometers.

7) 1KΩ undedicated potentiometer.

8) 100KΩ undedicated potentiometer.

1

2

3

4

5

6

7 8

-5-

INSTALL COMPONENTS TO PC BOARD

START HERE

ê

Figure B

Note: One side of the
bracket is longer.

Mount
this side to the PC board.
Mount the bracket to the
top legend side of the PC
board with a 4-40 x 1/4”
screw and fiber washer.

Bottom Left Corner of PC Board

Top Left Corner of PC Board

4-40 x 1/4”

Screw

Top Legend

Side of

PC Board

Fiber

Washer

Figure C

Mount down flush with PC board. The
value may be marked on the on the
back side of pot.

Cut off excess lead length after sol­dering.

Figure D

Bend the capacitor at a 45

o

angle before soldering.Cut off
excess leads.

Cut off tab

Figure A

Mount the connector as shown and solder the
pins of the connector.

PC Board

r S1 - 5-Pin Connector

(see Figure A)

r L-Bracket

(see Figure B)

r VR4 - 100KΩ Pot
r VR3 - 1KΩ Pot

(see Figure C)

r S3 - 3-Pin Connector
r S2 - 3-Pin Connector

(see Figure A)

r L-Bracket

(see Figure B)

r C8 - .1µF Mylar (104)

(see Figure D)

-6-

INSTALL COMPONENTS TO PC BOARD

START HERE

ê

Figure F

Cut a piece of bare wire long enough
so that 1/4” of wire passes through
each hole in the PC board after the
wire is formed.

Figure G

Diodes have polarity. Mount them
with the band as shown on the top
legend.

Band

Bottom Left Corner of PC Board

Figure E

These capacitors are polarized.
Be sure to mount them with the
“+” lead in the correct hole as
marked on the PC board. Mount
the capacitor lying flat on the PC
board as shown below.

(+)

(--)

r C11 - 100µF 25V

(see Figure E)

r R1 - 120Ω 5% 1/4W Resistor

(brown-red-brown-gold)

r C6 - .1µF Mylar (104)

(see Figure D)

r J28 - Jumper Wire

(see Figure F)

r J6 - Jumper Wire

(see Figure F)

r D12 - 1N4001 Diode
r D11 - 1N4001 Diode

(see Figure G)

r C14 - 100µF 25V Lytic
r C17 - 100µF 25V Lytic

(see Figure E)

r C10 - .1µF Mylar (104)

(see Figure D)

r R2 - 120Ω 5% 1/4W Resistor

(brown-red-brown-gold)

r J2 - Jumper Wire

(see Figure F)

r J3 - Jumper Wire

(see Figure F)

INSTALL COMPONENTS TO PC BOARD

START HERE

ê

Bottom Left Corner of PC Board

-7-

Figure H

Hold the bredblock down flush to
the PC board from the top legend
side and solder the metal pins in
place. Then, melt the plastic pins
with your soldering iron to hold the
plastic blocks in place, as shown.

Plastic Pins

Melt Pins

r VR1 - 2KΩ Pot
r VR2 - 2KΩ Pot

(see Figure C)

r B1 - 4 Pin Bredblox
r B2 - 4 Pin Bredblox
r B3 - 4 Pin Bredblox
r B4 - 4 Pin Bredblox

(see Figure H)

r C12 - 100µF 25V Lytic

(see Figure E)

r J26 - Jumper Wire
r J7 - Jumper Wire

(see Figure F)

r D15 - 1N4001 Diode
r D14 - 1N4001 Diode
r D13 - 1N4001 Diode

(see Figure G)

r C15 - 100µF 25V Lytic
r C16 - 100µF 25V Lytic

(see Figure E)

r J4 - Jumper Wire
r J1 - Jumper Wire

(see Figure F)

r C13 - 100µF 25V Lytic

(see Figure E)

-8-

INSTALL COMPONENTS TO PC BOARD

START HERE

ê

CONTINUE

ê

CONTINUE

ê

Bottom Right Corner of PC Board

Figure J

Diodes have polarity. Mount them with
the band as shown on the top legend.

Figure I

These lytics must be mounted hori­zontal to the PC board. Bend the
leads at right angles and then insert
the leads into the PC board with the
negative (--) lead and the positive
(+) lead in the correct holes as
marked on the PC board.

START HERE

ê

Top Right Corner
of PC Board

* Leftover wire will be used in

future sections.

Band

+

r C1 - 1000µF 35V Lytic
r C5 - 1000µF 35V Lytic

(see Figure I)

r C2 - 1000µF 35V Lytic
r C4 - 1000µF 35V Lytic

(see Figure I)

r C3 - 2200µF Lytic
Mount on foil side of PC board

Note the polarity

(see Figure I)

r D1 - 1N4001 Diode
r D2 - 1N4001 Diode
r D3 - 1N4001 Diode
r D4 - 1N4001 Diode
r D5 - 1N4001 Diode
r D6 - 1N4001 Diode
r D7 - 1N4001 Diode
r D8 - 1N4001 Diode
r D9 - 1N4001 Diode
r D10 - 1N4001 Diode

(see Figure J)

r L-Bracket

(see Figure B)

r C7 - .1µF Mylar (104)

(see Figure D)

r J5 - Jumper Wire *

(see Figure F)

r C9 - .1µF (104) Mylar

(see Figure D)

r L-Bracket

(see Figure B)

-9-

MOUNTING THE PC BOARD

Note: The holes in the two side panels have been punched differently. Be sure that you have the correct side

panel when mounting them to the PC board.

r Mount the PC board with four 4-40 x 1/4” screws (see Figure K). Do not tighten the screws.

r Place the top panel on top of the unit.Push the PC board up until the com-

ponents come through the top panel and tighten the screws.

Adjust the PC
board height
with a 4-40 x
1/4” screw

Figure KA

Note: From the foil side of the PC board,

inspect the edges to be sure that there
are no component leads shorting against
the side panels.

Figure K

MOUNT COMPONENTS TO THE SIDE PANELS

Mount U1, U3 and U5 to the left side panel as shown in Figure N. Insert the pins of each IC into the holes of
the PC board. Then, with the hardware shown in Figure M, attach each IC to the side panel. Solder the pins
of the ICs to the PC board.

r U3 - LM7805
r U1 - LM317
r U5 - LM337

-10-

Mount the solder lug to the panel, as shown in Figure N, using a 6-32 x 5/16” screw and 6-32 nut.
r Solder Lug

6-23 Nut

IC

* Silicone Grease

Mica

Side Panel

Insulator Washer

6-32 x 5/16” Screw

* Take a small amount of silicone grease from the
packet and apply it with a toothpick onto the back of
the ICs.

Mica

Figure M

Figure N

Figure L

-11-

WIRE THE TRANSFORMER TO THE PC BOARD

Cut the blue, red, white and yellow wires on the transformer so they are 3” long and strip the insulation off of
the ends to expose 1/4”of bare wire. Solder the wires to the PC board starting with the top yellow wire as shown
in Figure P.

r Yellow wire to point F on the PC board
r Blue wire to point A on the PC board
r Red wire to point C on the PC board
r White wire to point E on the PC board
r Red wire to point D on the PC board
r Blue wire to point B on the PC board
r Yellow wire to point G on the PC board

Yellow (F)
Blue (A)
Red (C)
White (E)
Red (D)
Blue (B)

Yellow (G)

Figure P

3”

Mount U2 and U4 to the right side panel as shown in Figure
O. Insert the pins of each IC into the holes in the PC board.
Then, with the hardware shown in Figure MA, attach each
IC to the side panel. Solder the pins of the ICs to the PC
board.

r U4 - LM7912
r U2 - LM7812

Mount the transformer with the black wires as shown in
Figure O. Use the two 8-32 x 3/8” screws, #8 lockwashers,
and 8-32 nuts.
r Transformer mounted

Right Side

U4

U2

7812

7912

Figure O

Black Wires

8-32 Nut

#8 Lock Washer

#8 Lock Washer

8-32 Nut

#8-32 x 3/8” Screws

Transformer

Note: Make sure that the transformer
does not touch U4.

6-23 Nut

IC

* Silicone Grease

Mica

Side Panel

Insulator Washer

6-32 x 5/16” Screw

* Take a small amount of silicone grease from the
packet and apply it with a toothpick onto the back of
the ICs.

Figure MA

Mica

Yellow (G)

Blue (B)

Blue (A)

Red (D)
White (E)
Yellow (F)

Red (C)

HOW TO INSTALL CONNECTORS ONTO TRANSFORMER WIRES

A connector will be placed in the primary wires of the transformer. This will allow you to remove the top panel
from the trainer. Follow the procedures below.

1. Cut a six inch length off of each black primary wire.

2. Strip the insulation off of each end of the six inch wires to expose 1/4” of bare wire.

3. Place one wire onto the female pin and crimp the outer crimp tabs with pliers over the insulation as shown
in Figure 1A.

4. Crimp the inner tabs with pliers onto the bare wire as shown in Figure 1B and then solder the wire to the pin.

5. Connect the other female pin to the other wire using the same procedures above.

A

B

Locking Tab

Female Pin

Solder

Outer

Crimp Tab

Inner
Crimp Tab

Female Housing

Figure 1

Figure 2

6. Insert the two pin/wire assemblies into the female housing as shown in Figure 2. Pull on the wire to check
that the pin is inserted all the way in. It should not pull out of the housing. The locking tabs should be bent
outward to hold the pin in the housing.

TRANSFORMER WIRES

1. Strip the insulation off of each of the black primary wires to expose 1/4” of bare wire.

2. Place the wire onto the male pin and crimp the outer crimp tabs with pliers over the insulation as shown in
Figure 3A.

3. Crimp the inner tabs with pliers onto the bare wire and then solder the wire to the pin as shown in Figure 3B.

4. Connect the other male pin to the other primary wire using the same procedures above.

5. Insert the two pin/wire assemblies into the male housing as shown in Figure 4. Pull on the wire to check that
the pin is inserted all the way in. It should not pull out of the housing.

6. Connect the male and female housing as shown in Figure 5. Note that the connector only fits together one
way.

7. To detach the connector, push down on the end of the lock arm and pull the two apart.

Figure 3

Figure 4

A

B

Locking Tab

Male Pin

Solder

Outer

Crimp Tab

Inner
Crimp Tab

Male Housing

Lock Arm

Figure 5

-12-

MOUNT COMPONENTS TO PANEL

r Push the illuminated switch into the hole in the top panel with the lugs as shown in Figure Q.
r Install the fuse holder with the side lug in the position shown in Figure Q. Fasten the fuse holder in place

with the nut as shown in Figure R. Unscrew the cap and insert the fuse into the holder.

Side

Lug

Fuse Holder

Illuminated Switch

Nut

Top Panel

Plastic Washer

Fuse Holder

Back Side - Lower

Right Corner

Figure Q

Figure R

r

There is a raised area on the back side of the top panel. Screw the spacer to the raised area by inserting a
4-40 x 1/4” flat head screw into the hole in the raised area from the top side of the panel (see Figure S).

r

When mounting the bredboard, use the holes shown in Figure Ta. Mount the plastic spacer with a 4-40 x 1/4” flat
head screw as shown in Figure S. Next, mount the bredboard with two #4 x 1/4” AB black screws from the back
side of the top panel as shown in Figure S. The negative (blue) stripe should be on top and the numbers read­ing from left to right should start with number 1 (see Figure Tb). CAUTION: Do not remove the paper backing
from the back of the bredboards. Do not over-tighten the black screws.

Spacer

4-40 x 1/4”

Flat Head

Screw

Top Panel

Bredboard

#4 x 1/4” AB Screws

Figure S

a

e

b

c

d

f

j

g

hi

1

5

10

ON

30VAC

+5

+12

--12

15VAC

OFF

15VAC

REGULATED

POWER SUPPLY

+

2

0

C

D

--

2

0

C

D

GND

Figure Tb

Figure T a

-13-

WIRE SWITCH AND FUSE HOLDER (see Figure U)

Fuse

r Slide the line cord bushing onto the line cord as shown in Figure U.
r Spread the three line cord wires apart 6” from the end.
r Strip the insulation off of both ends of the 6” red wire to expose 1/4” of bare wire. Pass the wire through the

1/2” diameter shrink tubing. Attach one end to the side lug on the fuse holder and then solder into place.

r Strip 1/4” of insulation off of the smooth edged line cord wire. Pass the smooth edged line cord wire through

the 1/2” diameter shrink tubing and attach to the end lug on the fuse holder, solder into place.

r Slide the shrink tubing over the fuse holder covering both lugs. Shrink the tubing for a snug fit. You may use

a hair dryer, heat gun (at lowest setting or you will melt the tubing) or the heat emitting from your soldering
iron (do not touch the tubing or the wires with the iron).

Switch

Disconnect the connector for the transformer.
r Pass the 6” strip of red wire (leading from the side lug of the fuse holder), the (A) and (B) black transformer

wire, and the ribbed line cord wire through the 3/4” diameter piece of shr ink tubing.

r

Cut the 2” section of 3/16” diameter shrink tubing in half to create two 1” sections. Slide a 3/16” diame­ter piece of shrink tubing over the loose end of the red wire. Attach the red wire to lug 1 on the switch
and then solder into place.

r Pass the black transformer wire labeled (B) through a 3/16” diameter piece of shr ink tubing. Attach the wire

to lug 2 on the switch and then solder into place.

r Slide the shrink tubing over lug 1 and lug 2 on the switch. Shrink the tubing into place.
r Strip the insulation off of the black transformer wire (A) and the ribbed edged line cord wire to expose 1/2” of

bare wire. Twist the two bare wires together. Pass the wires through the 1/4” diameter piece of shrink tub­ing. Attach the wires to lug 3 on the switch and solder into place. Slide the tubing over the lug. Shrink the
tubing into place.

r Slide the 3/4” diameter shrink tubing over the switch and shrink into place.
r Reconnect the connector for the transformer.

Switch Pin-out

1

2

3

Fuse Holder

Side Lug

6” Red Wire

1/2” Dia. Shrink Tubing

3/16” Dia. Shrink Tubing

(B) Black T r ansf ormer Wire

Female Connector

(A) Black T r ansf ormer Wire

Smooth Line Cord Wire

Ribbed Line Cord Wire

Green Line Cord Wire

Solder Lug

3/4” Dia. Shrink Tubing

1/4” Dia. Shrink Tubing

Switch

Figure U

-14-

Bushing

-15-

RESISTANCE ANALYSIS OF POWER SUPPLY

Static testing of the power supply circuits. Do not plug the power supply into the 120VAC power supply
source until all resistance readings check out. The values given below are approximate .

See Figure O for locations of testing points.

Resistance

From To Circuit Ohms Measured

1 Right Side Panel Ear th Ground less than 1Ω
2 3 On/Off Switch, Fuse Infinite (SW1 Off)
2 3 On/Off, Fuse 7Ω (SW1 On)
4 5 12V Secondary 1.5Ω
6 7 5V Secondary 1.2Ω
8 9 Variable Voltage 1.6Ω

10 GND 5-pin connector +12V Regulator Input greater than 20KΩ

11

(com) GND (VΩ)

(5-pin connector)

--12V Regulator Input greater than 20KΩ
12 GND (B1) +5V Regulator Input greater than 20KΩ
13 GND (B1) +Variable Regulator Input greater than 20KΩ

14

(com) GND (VΩ)

(5-pin connector)

--Variable Regulator Input greater than 20KΩ

25

(com) GND (VΩ)

(5-pin connector)

Voltage ADJ +20V Regulator

CCW <1Ω CW >1.4KΩ

26 GND (VΩ)

(5-pin connector)

Voltage ADJ -20V Regulator greater than 1.4KΩ
27 GND (5-pin connector) +5V Regulator GND less than 1Ω
28 GND (5-pin connector) +12V Regulator GND less than 1Ω
29 GND (5-pin connector) --12V Regulator GND less than 1Ω
10 15 +12V Regulator Input less than 1Ω
11 16 --12V Regulator Input less than 1Ω
12 17 +5V Regulator Input less than 1Ω
13 18 +Variable Regulator Input less than 1Ω
14 19 --Variable Regulator Input less than 1Ω
20 GND (5-pin connector) +Variable Regulator Output CCW 100Ω CW 2.12K
20 +20 (5-pin connector) +Variable Regulator Output less than 1Ω
21 GND (5-pin connector) --Variable Regulator Output CCW 100Ω CW 2.12K
21 --20 (5-pin connector) --Variable Regulator Output less than 1Ω
22 GND (5-pin connector) +5V Regulator Output greater than 5KΩ
22 B4 +5V Regulator Output less than 1Ω
23 GND (5-pin connector) +12V Regulator Output greater than 5KΩ
23 B3 +12V Regulator Output less than 1Ω
24 GND (5-pin connector) --12V Regulator Output greater than 5KΩ
24 B2 --12V Regulator Output less than 1Ω

5

15VAC (5-pin connector right)

15VAC less than 1Ω

4

15VAC (5-pin connector left)

15VAC less than 1Ω

«+

30% ²Note: meter lead polarity CCW - Counter Clockwise CW - Clockwise µVR1 & VR2 Adjustment

²

²

µ«
µ«

«

«

20A

2A COM VΩ

VΩ

COM