Elenco Electronics XK-550K User guide

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 #
r2 R1, R2 120Ω5% 1/4W (brown-red-brown-gold) 131200
r1 VR3 1KΩPot PC MNT 192412
r2 VR1, VR2 2KΩPot PC MNT 192421
r1 VR4 100KΩPot PC MNT 192612
CAPACITORS
QTY SYMBOL VALUE DESCRIPTION PART #
r5 C6 - C10 .1µF 100V Mylar 251017
r7 C11 - C17 100µF Electrolytic 281045
r4 C1, C2, C4, C5 1000µF 35V Electrolytic 291096
r1 C3 2200µF 25V Electrolytic 292225
SEMICONDUCTORS
QTY SYMBOL DESCRIPTION PART #
r15 D1 - D15 1N4001 Diode 314001
r1 U1 LM317 Integrated Circuit 330317
r1 U5 LM337 Integrated Circuit 330337
r1 U3 LM7805 Integrated Circuit 337805
r1 U2 LM7812 Integrated Circuit 337812
r1 U4 LM7912 Integrated Circuit 337912
MISCELLANEOUS
QTY DESCRIPTION PART #
r1 Transformer 44K500
r1 PC Board 514550
r1 Fuse 1.25A 530125
r1 Switch Illuminated 541204
r2 Connector 3-pin 591032
r1 Connector 5-pin 591052
r1 Bracket 613003
r4 Bracket L 4-40 tap 613008
r1 Panel Top 614102
r1 Panel Side Right 614551
r1 Panel Side Left 614554
r4 Knob 622009
r1 Case 623002
r1 Bushing 624009
r1 Spacer Nylon 7/16” x 3/16” Tap 624013
r1 Connector Receptacle 626020
r1 Connector Plug 626021
r1 Cord Retainer 628003
r9 Screw 4-40 x 1/4” Slotted 641430
r1 Screw 4-40 x 1/4” Phillips 641431
r8 Screw 6-32 x 5/16” Slotted 641641
r2 Screw 8-32 x 3/8” Phillips 641840
r2 Screw #4 x 1/4” Phillips AB 642430
r4 Screw #8 x 1/2” Phillips AB 642862
r4 Screw #6 x 3/8” Phillips Thrd Ct 643652
QTY DESCRIPTION PART #
r4 Nut 7mm 644101
r8 Nut 6-32 644601
r2 Nut 8-32 644800
r4 Washer 8mm x 14mm (Pot) 645101
r4 Washer Fiber 645404
r2 Lockwasher #6 INT 646600
r2 Lockwasher #8 EXT 646828
r1 Lug Solder #8 661002
r1 Fuse Holder 663000
r4 Bredblox 4-pin 665204
r2 Terminal Male Crimp 666010
r2 Terminal Female Crimp 666011
r1 Label (XK-550K) 723501
r1 Manual 753550K
r5 Insulator Mica 780002
r5 Insulator Washer 780101
r1 Silicon Grease 790004
r6” Wire #20 Red Stranded 813210
r2.5’ Wire #22 Bare Wire 845000
r1 Line Cord 862105
r2” Shrink Tubing 3/16” 890120
r1” Shrink Tubing 1/4” 890701
r2” Shrink Tubing 1/2” 891101
r2” Shrink Tubing 3/4” 899110
r1 Solder Tube 9ST4A
Screw Identification
Phillips AB Screw 4-40 / #6 Thread Cutting Screw Standard Screw
(Type 23)
Flat Head Screw

-2-
PARTS VERIFICATION
Before beginning the assembly process, first familiarize yourself with the components and this instruction book.
Verify that all parts 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 value printed on them. Some capacitors may have their value printed in the following man-
ner.
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 indicated. 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 form solder shorts. 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 simulta-
neously 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 con-
nection, 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.To
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 sur-
rounds and insulates the con-
nection.
Poor solder
connection
Mount Part
Soldering iron posi-
tioned incorrectly.
Example 2
A solder bridge occurs when
solder runs between circuit
paths and creates a short cir-
cuit. This is usually caused by
using too much solder. To cor-
rect this, simply drag your sol-
dering 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 connec-
tion 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 - 100Ω5% 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 DG-
550D. 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 wave-
forms. 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 vari-
able between 0 to 15Vpp. The output impedance is approximately 330 ohms.
DIGITAL TRAINER SECTION
The digital trainer has the necessary functions to do your digital experiments. They consist of a clock genera-
tor, 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-internal IC thermal cutoff.
• Fuse 1.25A 250V.
Variable Resistance (undedicated):
• 1KΩPotentiometer
• 100KΩPotentiometer
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) 1KΩundedicated potentiometer.
8) 100KΩundedicated 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 sol-
dering.
Figure D
Bend the capacitor at a 45o
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
rS1 - 5-Pin Connector
(see Figure A)
rL-Bracket
(see Figure B)
rVR4 - 100KΩPot
rVR3 - 1KΩPot
(see Figure C)
rS3 - 3-Pin Connector
rS2 - 3-Pin Connector
(see Figure A)
rL-Bracket
(see Figure B)
rC8 - .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.
(+)
(--)
rC11 - 100µF 25V
(see Figure E)
rR1 - 120Ω5% 1/4W Resistor
(brown-red-brown-gold)
rC6 - .1µF Mylar (104)
(see Figure D)
rJ28 - Jumper Wire
(see Figure F)
rJ6 - Jumper Wire
(see Figure F)
rD12 - 1N4001 Diode
rD11 - 1N4001 Diode
(see Figure G)
rC14 - 100µF 25V Lytic
rC17 - 100µF 25V Lytic
(see Figure E)
rC10 - .1µF Mylar (104)
(see Figure D)
rR2 - 120Ω5% 1/4W Resistor
(brown-red-brown-gold)
rJ2 - Jumper Wire
(see Figure F)
rJ3 - 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
rVR1 - 2KΩPot
rVR2 - 2KΩPot
(see Figure C)
rB1 - 4 Pin Bredblox
rB2 - 4 Pin Bredblox
rB3 - 4 Pin Bredblox
rB4 - 4 Pin Bredblox
(see Figure H)
rC12 - 100µF 25V Lytic
(see Figure E)
rJ26 - Jumper Wire
rJ7 - Jumper Wire
(see Figure F)
rD15 - 1N4001 Diode
rD14 - 1N4001 Diode
rD13 - 1N4001 Diode
(see Figure G)
rC15 - 100µF 25V Lytic
rC16 - 100µF 25V Lytic
(see Figure E)
rJ4 - Jumper Wire
rJ1 - Jumper Wire
(see Figure F)
rC13 - 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 hori-
zontal 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
êTop Right Corner
of PC Board
* Leftover wire will be used in
future sections.
Band
+
rC1 - 1000µF 35V Lytic
rC5 - 1000µF 35V Lytic
(see Figure I)
rC2 - 1000µF 35V Lytic
rC4 - 1000µF 35V Lytic
(see Figure I)
rC3 - 2200µF Lytic
Mount on foil side of PC board
Note the polarity
(see Figure I)
rD1 - 1N4001 Diode
rD2 - 1N4001 Diode
rD3 - 1N4001 Diode
rD4 - 1N4001 Diode
rD5 - 1N4001 Diode
rD6 - 1N4001 Diode
rD7 - 1N4001 Diode
rD8 - 1N4001 Diode
rD9 - 1N4001 Diode
rD10 - 1N4001 Diode
(see Figure J)
rL-Bracket
(see Figure B)
rC7 - .1µF Mylar (104)
(see Figure D)
rJ5 - Jumper Wire *
(see Figure F)
rC9 - .1µF (104) Mylar
(see Figure D)
rL-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.
rMount the PC board with four 4-40 x 1/4” screws (see Figure K). Do not tighten the screws.
rPlace 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.
rU3 - LM7805
rU1 - LM317
rU5 - 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.
rSolder 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.
rYellow wire to point F on the PC board
rBlue wire to point A on the PC board
rRed wire to point C on the PC board
rWhite wire to point E on the PC board
rRed wire to point D on the PC board
rBlue wire to point B on the PC board
rYellow 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.
rU4 - LM7912
rU2 - 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.
rTransformer 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.
AB
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
AB
Locking Tab
Male Pin Solder
Outer
Crimp Tab Inner
Crimp Tab
Male Housing
Lock Arm
Figure 5
-12-

MOUNT COMPONENTS TO PANEL
rPush the illuminated switch into the hole in the top panel with the lugs as shown in Figure Q.
rInstall 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 FigureTa. 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 read-
ing 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
ae
bcdfj
ghi 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 Ta
-13-

WIRE SWITCH AND FUSE HOLDER (see Figure U)
Fuse
rSlide the line cord bushing onto the line cord as shown in Figure U.
rSpread the three line cord wires apart 6” from the end.
rStrip 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.
rStrip 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.
rSlide 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.
rPass 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 shrink tubing.
r
Cut the 2” section of 3/16” diameter shrink tubing in half to create two 1” sections. Slide a 3/16” diame-
ter 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.
rPass the black transformer wire labeled (B) through a 3/16” diameter piece of shrink tubing. Attach the wire
to lug 2 on the switch and then solder into place.
rSlide the shrink tubing over lug 1 and lug 2 on the switch. Shrink the tubing into place.
rStrip 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 tub-
ing. Attach the wires to lug 3 on the switch and solder into place. Slide the tubing over the lug. Shrink the
tubing into place.
rSlide the 3/4” diameter shrink tubing over the switch and shrink into place.
rReconnect the connector for the transformer.
Switch Pin-out
12
3Fuse Holder
Side Lug
6” Red Wire
1/2” Dia. Shrink Tubing
3/16” Dia. Shrink Tubing
(B) Black Transformer Wire
Female Connector
(A) Black Transformer 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 Earth 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 <1ΩCW >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 100ΩCW 2.12K
20 +20 (5-pin connector) +Variable Regulator Output less than 1Ω
21 GND (5-pin connector) --Variable Regulator Output CCW 100ΩCW 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

-16-
Locations for Testing Points
•••
21
19
26
•••
18
20
25
•••
22
27
17
5 pin connector left
5 pin connector +20
5 pin connector right
5 pin connector -20
GND
Ground
•••
29
16
24
•••
15
28
23
9
8
7 6
5
4
10
11
12 13
14
+20V
Pot -20V
Pot
Plug of line cord
1
3
2
Figure O
B1
LM-7812 LM-7912
LM-7805 LM-317 LM-337
On test points 4 - 14
use the leads of the
diodes.

VOLTAGE ANALYSIS OF POWER SUPPLY
Proceed with the voltage analysis only if the resistance readings were satisfactory.
Place the top panel on the unit. If any capacitors are inserted backwards, the panel will shield you if
they explode. Make sure that the ON/OFF switch is in the OFF position. Plug the line cord into the 120VAC
power source. Turn the unit on and let it sit for a few minutes. Turn OFF the ON/OFF switch and remove the
top panel, placing it along the left side of the trainer. Turn ON the ON/OFF switch and measure the voltage point
as listed in the chart below. The values given are approximate.
See Figure V for locations of the testing points.
From To Circuit Volts Volts Measured
15 GND +12V Regulator Input +21V
B3 GND +12V Regulator Output +12V
16 GND -12V Regulator Input -21V
B2 GND -12V Regulator Output -12V
17 GND +5V Regulator Input +12.5V
B4 GND +5V Regulator Output +5V
18 GND +20V Regulator Input +28V
25 GND Voltage ADJ +20V Regulator CCW 0V CW +18V
+20 5 pin connector GND +20V Output
CCW +1.25V CW +20V
19 GND -20 Regulator Input -28V
26 GND Voltage ADJ -20V Regulator CCW 0V CW -18V
-20 5 pin connector GND -20V Output CCW -1.25V CW -20V
15VAC 15VAC 30VAC 30VAC
5-pin 5-pin
connector connector
left right
«
«
«
«
«+30% CCW - Counter-Clockwise CW - Clockwise
rTurn unit off.
-17-
FUSE REPLACEMENT
1. Turn the trainer off and unplug it from 120VAC power source.
2. Unscrew fuse holder cap and remove fuse.
3. Use only a 1.25A fuse. Larger fuses or other fuse bypass will void the war-
ranty of the trainer.
4. Place the new fuse into the fuse holder cap and screw it back into the holder.
5. Plug trainer into 120VAC power source and turn the unit on.
Place the top panel on top of the unit.

-18-
POWER SUPPLY TESTING
Plug the trainer into a 120VAC outlet and switch to the “ON” position (the power switch should light). With a dig-
ital voltmeter, measure the voltage outputs at the power blocks. The +12V should measure between 11.4 and
12.6 volts. The 5V supply should read between 4.75 and 5.25 volts. The -12V supply should read between -
11.4 and 12.6 volts.
Do not short the 15VAC output to ground.
Short the +12V, -12V and +5V supply to ground. They should turn off and recover when the short is removed.
If you have a 25Ω10 watt resistor, place it across the output terminal (2 watt resistor will work, but use it only
for a few seconds). The output of the 12V supply should not change more than .20 volts. Do the same on the
5V supply using a 10Ω5 watt resistor. Again, the output should not change more than .20 volts. In making this
test, the voltmeter leads should be clipped to the terminal directly and no to the load leads. This is to prevent
errors due to voltage drop from contact resistance of the load.
Check the variable voltage supplies in the same manner. Set the output voltage between 10-15 volts. Place
the 25Ω10 watt resistor across the output terminal. The voltage should stay within .20 volts of the no load volt-
age.
TROUBLESHOOTING CHART
This chart lists the condition and possible causes of several malfunctions. If a particular part is mentioned as
a possible cause, check that part to see if it was installed correctly. Also, check it and the parts connected to it
for good solder connections. Note: The values given in this troubleshooting chart are an approximation.
PROBLEM POSSIBLE CAUSE
Switch doesn’t light. 1. Check fuse and line cord.
Fuse blows when the unit is turned on. 1. Voltage supply shorted to GND. Use resistance analysis
chart to find short.
No or low voltage at positive variable 1. Measure for an AC voltage of 18VAC at anode of D7 & D9.
output. A. Transformer and/or secondary connection to PC
board defective
2. Measure for a DC voltage of 28VDC at pin 3 of U1 LM317.
A. Diodes D7, D9 in backwards or defective, check
capacitor C1.
3. Set the voltage for minimum 1.25VDC and measure pin 2
of U1.
A. Voltage adjusts only from 7.8 - 9.8V R1 open or
defective.
B. Voltage 27V, check VR1 connections.
No or low voltage at positive variable 1. Check that capacitor C1 1000µF is inserted in the correct
output with load. polarity.
2. Check ripple on pin 3 of U1. 8VP-P Max.
A. Capacitor C1, and/or diodes D7, D9 defective.

-19-
PROBLEM POSSIBLE CAUSE
No voltage at negative variable output. 1. Measure for an AC voltage of 18VAC at cathode of D8, D10.
A. Transformer and/or secondary connection to PC board
defective.
2. Measure DC voltage of -28VDC at pin 2 of U5 LM337.
3.
Set voltage for minimum -1.25VDC and measure pin 3 of U5.
A. Voltage adjusts only from -7.8 to -9.8V R2 open or
defective.
B. Voltage -27V, check VR2 connections.
No or low voltage at negative variable 1. Check to see if capacitor C5 1000µF is inserted in the
output with load. correct polarity.
2. Check ripple on pin 2 of U5. 6VP-P max.
A. Capacitor C5 and/or diodes D8, D10 defective.
No +12V at output. 1. Measure an AC voltage of 15VAC at anode of D1, D3.
A. Transformer and/or secondary connection to PC board
defective.
2. Measure for a DC voltage of 21VDC at pin 1 of U2 LM7812.
A. Diodes D1, D3 in backwards or defective, check
capacitor C1.
3. Measure for a DC voltage of 12VDC on pin 3 of U2.
A. U2 LM7812 defective or open ground.
No +12V at output with load. 1. Check capacitor C2 1000µF is inserted in the correct
polarity.
2. Check ripple on pin 1 of U2. 7VP-P Max.
A. Capacitor C2 or diodes D1, D3 defective.
No -12V at output. 1. Measure an AC voltage of 15VAC at anode of D2, D4.
A.Transformer and/or secondary connection to PC board
defective.
2. Measure for a DC voltage of -21VDC at pin 2 of U4 LM7912.
A. Diodes D2, D4 in backwards or defective, check
capacitor C4.
3. Measure for a -12VDC voltage on pin 3 of U4.
A. U4 LM7912 defective or open ground.
No -12V at output with load. 1. Check capacitor C4 is inserted in the correct polarity.
2. Check ripple on pin 2 of U3. 7VP-P Max.
A. Capacitor C4 and/or diodes D1, D3 defective.
No +5VDC at output 1. Measure an AC voltage of 9VAC at anode of D5, D6.
A. Transformer and/or secondary connection to PC board
defective.
2. Measure for a DC voltage of 12VDC at pin 1 of U3 LM7805.
A. Diodes D5, D6 in backwards or defective, check
capacitor C3.
3. Measure for a 5VDC voltage on pin 3 of U3 LM7805.
A. U3 LM7805 defective or open ground.
No +5VDC at output with load. 1. Check that capacitor C3 is inserted in the correct polarity.
2. Check ripple on pin 1 of U3. 4VP-P Max.
A. Capacitor C3 and/or diodes D5, D6 defective.