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K2/100
User Manual
74 pgs2.82 Mb0

ELECRAFT K2/100 User Manual

1
Appendix G, 100-W Stage and RS-232 I/O (K2/100) Rev H3, July 24, 2017
E740035
2
Table of Contents
i
Elecraft manuals with color images may be downloaded from www.elecraft.com.
3
Introduction
Appendix G describes assembly of the K2/100 transceiver's internal 100­watt final output stage (KPA100 board). The PC board includes two conservatively-rated RF power transistors, low-pass filters, SWR bridge, monitoring circuits, speaker, and an RS-232 interface. Filter switching, T­R sequencing, and other configuration is handled by the K2/100's main microcontroller.
KPA100 assembly and installation should be done only after the transceiver has been aligned and tested at the 10-watt level.
Upgrades Recommended for Older K2s
All K2 owners are encouraged to keep their transceivers up to date by making recommended changes. These changes should be installed and tested before the KPA100 is installed.
K2 s/n 4059 or lower: K2 keying bandwidth modification (order #K2KEYMODKT). This modification is strongly recommended for CW operators, especially if you use high power. Note: Requires upgrade to revision 2.04 or later K2 firmware (order #FWK2MCIO).
K2 s/n 3445 or lower: PLL Upgrade (order #E850138). This ensures excellent VFO temperature stability during high-power operation.
K2 s/n 2999 or lower: (1) 10 meter band-pass filter and VFO ALC modification (#E850093, supplied with your KPA100 kit). (2) BFO modification (order #BFOMDKT). You should also make all applicable changes described in this document:
http://www.elecraft.com/manual/k2a2binstr.pdf
Pre-Wound Toroids Available
The toroids used in the KPA100 are not difficult to wind, and full instructions are provided. If you prefer not to wind them yourself, you can obtain a full set of pre-wound toroids from an Elecraft-qualified source. Ordering information can be found on our web site, www.elecraft.com. You do not need to send your cores or wire to the
winding service.
Preparation for Assembly
With all equipment that operates at high power levels, proper assembly and alignment are critical for safe and reliable operation. Follow the instructions carefully and make all of the recommended measurements. Do not substitute components or perform any assembly steps out of order.
Please read the following information regarding tools before proceeding.
Tools Required
The following tools are required to build this kit:
Flush-cutters (Hakko CHP-170, Xcelite 170, etc.). Ordinary
diagonal cutters are not suitable for flush-cutting (trimming leads very close to the board).
Temperature-controlled soldering station with a fine-point, 700
to 800-degree (F) tip. Do not use a high-wattage iron or gun with
small components, since this can damage pads, traces, or the parts themselves.
Larger iron or soldering gun. This will be used only for installation
of power transistors, output transformer, and DC power wiring. A low-wattage iron cannot be used for these steps.
Digital Multimeter (DMM). A DMM with diode-checking
capability. Capacitance measurement capability is desirable, though not required.
4
Customer Service Information
Technical Assistance
You can send e-mail to support@elecraft.com and we will respond quickly - typically the same day Monday through Friday. Telephone assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays only) at 831-763-4211. Please use e-mail rather than calling when possible since this gives us a written record of the details of your problem and allows us to handle a larger number of requests each day.
Repair / Alignment Service (We want to make sure everyone
succeeds!)
If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer unlimited email and phone support to get your kit running, so please try that route first as we can usually help you find the problem quickly.)
IMPORTANT: You must contact Elecraft before mailing your product to obtain authorization for the return, what address to ship it to
and current information on repair fees and turnaround times. (Frequently we can determine the cause of your problem and save you the trouble of shipping it back to us.) Our repair location is different from our factory location. We will give you the address to ship your kit to at the time of repair authorization. Packages shipped us without authorization will
incur an additional shipping charge for reshipment to our repair depot.
To ship the unit, first seal it in a plastic bag to protect the finish. Use a sturdy packing carton with at least 3-in (8 cm) of foam or shredded paper on all sides. Seal the package with reinforced tape. (Neither Elecraft or the carrier will accept liability for damage due to improper packaging.)
Elecraft's 1-Year Limited Warranty
This warranty is effective as of the date of first consumer purchase (or if shipped from factory, date product is shipped to customer). It covers both our kits and fully assembled products. For kits, before requesting warranty service, you should fully complete the assembly, carefully following all instructions in the manual.
Who is covered: This warranty covers the original owner of the Elecraft product as disclosed to Elecraft at the time of order. Elecraft products transferred by the purchaser to a third party, either by sale, gift or other method, who is not disclosed to Elecraft at the time of original order, are not covered by this warranty. If the Elecraft product is being bought indirectly for a third party, the third party's name and address must be provided to Elecraft at time of order to insure warranty coverage.
What is covered: During the first year after date of purchase, Elecraft will replace defective or missing parts free of charge (post-paid). We will also correct any malfunction to kits or assembled units caused by defective parts and materials. Purchaser pays inbound shipping to Elecraft for warranty repair, Elecraft will pay shipping to return the repaired equipment to you by UPS ground service or equivalent to the continental USA and Canada. Alaska, Hawaii and outside U.S. and Canada actual return shipping cost paid by owner.
What is not covered: This warranty does not cover correction of kit assembly errors. It also does not cover misalignment; repair of damage caused by misuse, negligence, or builder modifications; or any performance malfunctions involving non-Elecraft accessory equipment. The use of acid-core solder, water-soluble flux solder, or any corrosive or conductive flux or solvent will void this warranty in its entirety. Also not covered is reimbursement for loss of use, inconvenience, customer assembly or alignment time, or cost of unauthorized service.
Limitation of incidental or consequential damages: This warranty does not extend to non-Elecraft equipment or components used in conjunction with our products. Any such repair or replacement is the responsibility of the customer. Elecraft will not be liable for any special, indirect, incidental or consequential damages, including but not limited to any loss of business or profits.
5
Parts Inventory
Set the heat sink, shield, and painted panels aside until needed. Leave them wrapped to protect their finish.
You should do a complete inventory (see below), which may take an hour or more. If anything is missing, contact Elecraft. Color codes and other
markings are shown in parentheses. Refer to Appendix A of the owner's manual for more parts photos.
Some components in this kit can be damaged by static discharge. Before handling diodes, transistors, and ICs, touch a grounded, unpainted metal surface, or use a wrist strap.
Parts List Notes:
LS = lead spacing in inches (metric conversions: 0.1" = 2.5 mm, 0.2" = 5 mm, 0.4" = 10 mm.) In some cases, two capacitor types will have the same value but different voltage ratings or lead spacing (LS). To avoid assembly errors, you
must positively identify these capacitors and keep them separate from each other. Use your DMM to verify values if possible.
Parts whose reference designators are shown in bold are for use on the K2 RF or Control boards. Flat-head screws are measured from the top of the head; pan head screws are measured from beneath the head.
Picture
Ref. Designator(s)
QTY
Description
Part #
C5B 1 Cap., 18 pF ("18"), 5%, 500V or 1KV disc, 0.2" LS (may have black band)
E530088
C3B,C4B
2
Cap., 27 pF ("27"), 5%, 500V or 1KV disc, 0.2" LS
E530089
C5F 1 Cap., 33 pF ("33"), 5%, 500V or 1KV disc, 0.2" LS
E530090
C3H 1 Cap., 39 pF ("39"), 5%, 500V or 1KV disc, 0.2" LS
E530091
C5D 1 Cap., 47 pF ("47"), 5%, 500V or 1KV disc, 0.2" LS
E530092
C4D 1 Cap., 56 pF ("56"), 5%, 500V or 1KV disc, 0.2" LS (may have black band)
E530093
C5A,C6C
2
Cap., 68 pF ("68"), 5%, 500V or 1KV disc, 0.2" LS
E530094
C3E,C5G
2
Cap., 82 pF ("82"), 5%, 500V or 1KV disc, 0.2" LS
E530095
C4E 1 Cap., 120 pF ("121"), 5%, 500V or 1KV disc, 0.2" LS
E530096
C3G,C4A,C5C,C5E, C6E
5
Cap., 150 pF ("151"), 5%, 500V or 1KV disc, 0.2" LS
E530097
C2B,C3C,C3J
3
Cap., 220 pF ("221"), 5%, 500V or 1KV disc, 0.2" LS
E530098
C3A,C3D,C4C,C6F
4
Cap., 270 pF ("271"), 5%, 500V or 1KV disc, 0.2" LS
E530099
C3F,C6A,C6B,C6G
4
Cap., 330 pF ("331"), 5%, 500V or 1KV disc, 0.2" LS
E530100
C2D 1 Cap., 390 pF ("391"), 5%, 500V or 1KV disc, 0.2" LS
E530101
C26
1
Cap., 33 pF ("33"), 5%, 50V disc, 0.2" LS (do not confuse with C5F)
E530064
C41,C95
2
Cap., 100 pF ("101"), 5%, 200V disc, 0.2" LS
E530034
6
Picture
Ref. Designator(s)
QTY
Description
Part #
C66 1 Cap., 180 pF ("181"), 5%, 50V disc, 0.2" LS; voltage may not be marked
E530008
C67,C80,C81,C86
4
Cap., .0047 µF ("472"), 10%, 100V disc, 0.25" LS
E530102
C2E,C83
2
Cap., 1000 pF ("1000"), 5%, 500V silver mica
E530085
C2A,C6D
2
Cap., 1200 pF ("6122"), 630V polypropylene
E530033
C2C 1 Cap., 2200 pF ("2200"), 5%, 500V silver mica
E530086
C84
1
Cap., .001 µF ("102"), 5%, 50V mono, 0.1" LS
E530074
C25,C69,C70,C87, C88, CTRL-Ctxd
6
Cap., .001 µF ("102"), 5%, 50V mono, 0.2" LS (CTRL-Ctxd may be needed for K2 Control board; see text)
E530001
C82 0 Not used
-
C71
1
Cap., .0018 µF ("182"), 5%, 200V mono, 0.2" LS
E530104
C64, C79
2
Cap., .0047 µF ("4n7J250"), 5%, 250Vor greater, mono, 0.4" LS
E530262
C7,C8,C9,C12–C22, C24,C28,C29,C32, C50,C65,C72,C73, C74,C76,C97–C99
27
Cap., .01 µF ("103"), 5%, 50V mono, 0.1" LS
E530019 C37,C38,C39,C44,
C46,C68,C89,C90
8
Cap., .01 µF ("103"), 5%, 50V mono, 0.2" LS
E530009
C36,C42,C43,C77
4
Cap., .015 µF ("153" or "15N"), 5%, 250V mono, 0.2" LS
E530082
C31 1 Cap., .22 µF ("µ22J63"), 5%, 63V mono, 0.2" LS
E530295
C48,C49,C52,C53, C54,C55,C56,C57, C61,C62,C63,C85
RF-Crf
13
Cap., .047 µF ("473"), 5%, 50V mono, 0.2" LS (RF-Crf may be needed for the K2 RF board; see text)
E530025 C30,C33,C34,C75
4
Cap., 0.1 µF ("104"), 20%, 50V mono, 0.1" LS
E530020
C10,C11,C23,C35, C58,C59,C40,
CTRL-C42
8
Cap., 0.1 µF ("104"), 5%, 50V mono, 0.2" LS (CTRL-C42 may be needed for the K2 Control board; see text)
E530011 C27 1 Cap., 10-50 pF ceramic trimmer, yellow color
E540002
C1
1
Cap 3-11 ceramic trimmer, white color:
NOTE: This trimmer is packaged in a separate envelope to help you avoid confusing it with C27. Keep it in its envelope until you are instructed to install it.
E540012 C60 1 Cap., 100 µF, 16V electrolytic
E530061
C51 1 Cap., 470 µF, 25V electrolytic
E530084
D1-D8
8
Diode, 1N4148
E560002
D9 1 Diode, SB530
E560003
D10,D13
2
Diode, 1N5404
E560010
D11,D12,D14
3
Diode, 1N4007
E560001
7
Picture
Ref. Designator(s)
QTY
Description
Part #
D16,D17
2
Diode, 1N5711
E560004
E1 1 Ground terminal, right angle PCB mount, 6-32 threaded
E700012
FAN1
1
Fan, 12 V
E980046
J2 1 Connector, SO239 (Antenna)
E620064
J3, P3
2
Connector, DC power, red housing (13.8 VDC input and mating conn., +)
E620059
J3, P3
2
Connector, DC power, black housing (13.8 VDC input and mating conn., -)
E620060
MISC
2
PCB pin for J3, 25 amp right angle
E620061
MISC
2
Crimp/solder terminal for P3, 30 amps
E620062
HDWR
2
Mounting plate for J3
E620063 MISC
1
Spring pin, 3/32" x 1/4" (2.4 x 6.4 mm); stabilizing pin for P3
E700071 J1,J4 2 Connector, 2p female housing, 0.156" spacing (12V and RF connectors)
E620013
RF-P3, RF-P6
2
Mating connectors for J1 and J4, 2p male, 0.156" spacing (K2 RF board)
E620012
HDWR
5
Crimp/solder terminal for J1 and J4, gold color (1 spare)
E620014
J5 1 Connector, 2p female housing, 0.1" spacing (AF In)
E620021
HDWR
3
Crimp/solder terminal for J5 (1 spare)
E620022
J6 1 Connector, 1/8" mono jack w/switch, PCB mount (ext. speaker)
E620056
J7 1 Connector, RCA jack, PCB mount (ext. PA key)
E620057
J8 1 Connector, DB9F, PCB mount (RS-232 interface)
E620058
8
Picture
Ref. Designator(s)
QTY
Description
Part #
MISC
2
Keying insert for ribbon cable connector (Shown approx. 4x actual size; may include large break-away tab)
E700065 MISC
1
Connector, DB9M (serial I/O cable, K2 end)
E620049
MISC
1
Connector, DB9F (serial I/O cable, PC end)
E620048
MISC
2
Backshell for serial I/O cable
E620050
K1-K12
12
Relay, SPDT, 12 V
E640011
L1,L2,L13,L14
4
Toroidal ind., T50-2 core (iron powder, red, 0.5" dia.)
E680005
L4-L8,L10-L12
8
Toroidal ind., T50-10 core (iron powder, black, 0.5" dia.) Note: One FT50-43 gray ferrite core, also 0.5" dia,, is supplied (see T4). The T50-10 iron power cores have a shiny, black finish, while the ferrite core is dull gray. Label the ferrite core to avoid confusing it with the eight iron powder cores.
E680016
L16, RFC1
2
Toroidal ind., T50-1 core (iron powder, blue, 0.5" dia.)
E680001
L18 0 Jumper (see text)
n/a
P1 1 Connector, 10 pin dual row (5 x 2), 0.1" spacing
E620040
Q1,Q2
1
Matched set of (2) 2SC2879 transistors
E850123
Q3,Q4
2
Transistor, NPN, MJE182, TO-225AA package
E580016
Q5,Q8
2
Transistor, NPN, 2N3904, TO-92
E580017
Q6,Q7
2
Transistor, MOSFET, 200 V, ZVN4424, TO-92
E580005
Q10,Q11,Q12
3
Transistor, MOSFET, 60 V, 2N7000, TO-92
E580002
Q9 1 Transistor, HEXFET, 500 V, IRF830 or IRL620, TO-220 (tab may be cut)
E580018
R2,R3
2
Resistor, 2.7 ohms, 5%, 1/4 W (RED-VIO-GOLD)
E500055
R9 1 Resistor, 10 ohms, 5%, 1/4 W (BRN-BLK-BLK)
E500054
R10 1 Resistor, 47, 5%, 1/4 W (YEL-VIO-BLK)
E500019
R33 1 Resistor, 1000 ohms, 5%, 1/4W (BRN-BLK-RED)
E500013
R1,R29,R15,R16
4
Resistor, 3.3 k, 5%, 1/4 W (ORG-ORG-RED)
E500017
R8 1 Resistor, 10 k, 5%, 1/4 W (BRN-BLK-ORG)
E500015
R5 1 Resistor, 15 k, 5%, 1/4 W (BRN-GRN-ORG)
E500060
R4 1 Resistor, 100k, 5%, 1/4W (BRN-BLK-YEL)
E500006
R11 1 Resistor, 510 k, 5%, 1/4W (GRN-BRN-YEL)
E500069
R32
1
Resistor, 100 ohms, 1%, 1/4W (BRN-BLK-BLK-BLK) Note: Don't confuse R32 with 100-µH RF choke RFC3. RF chokes can be identified by their much lower DC resistance (typically 1 to 8 ohms).
E500059 R30 1 Resistor, 3.09 k, 1%, 1/4W (ORG-BLK-WHT-BRN)
E500072
R24,R25
2
Resistor, 8.45 k, 1%, 1/4W (GRY-YEL-GRN-BRN)
E500071
R28,R31
2
Resistor, 200 ohms, 5%, 1W (RED-BLK-BRN) or (201J)
E500074
R40 1 Resistor, 22K, 5%, 1/4W (RED-RED-ORG)
E500090
9
Picture
Ref. Designator(s)
QTY
Description
Part #
R23 0 Resistor, 0 ohms (jumper); see text
n/a
R14 1 Resistor, 470 ohms, 5%, 1W (YEL-VIO-BRN)
E500075
R19,R20
2
Resistor, 1.6 ohms, 5%, 2W
E500177
R21,R34,R35
3
Resistor, 10 ohms, 5%, 2W
E500077
R38,R39
2
Resistor, 22 ohms, 5%, 3W
E500128
R22 1 Resistor, 300 ohms, 5%, 2W
E500129
R13 1 Resistor, 100 ohms, 5%, 3W
E500080
R7 1 Resistor, .005 ohms, 1%, 3W (current sensing)
E500079
R6 1 Potentiometer, 1K trimmer ("102"), bias set
E520010
R26,R27
2
Potentiometer, 100K trimmer ("104"), SWR set
E520001
RFC3,RFC11
2
RF Choke, 100 µH (BRN-BLK-BRN), 0.4" LS
E690016
RFC4, RFC5, RFC9
3
RF Choke, 15 µH (BRN-GRN-BLK), 0.4” LS
E690006
RFC6,RFC7,RFC8
3
RF Choke, 100 µH, miniature (BRN-BLK-BRN), 0.2" LS
E680013
RP1 1 Resistor network, 3.9 k, 8 pins (marked part number should include "392")
E510000
SP1 1 Speaker, 4 ohms, 3W
E980007
T1 1 Transformer, small binocular toroid core (gray, approx. 0.5" x 0.75")
E680014
T2 1 Transformer, large binocular toroid core (gray, approx. 1" x 1.2")
E680015
T3 1 Transformer, FT37-61 toroidal core (gray, 0.37" dia.)
E680002 T4 1 Transformer, FT50-43 toroidal core (gray, 0.5" dia.)
E680008
U1 1 IC, PIC16F872 microcontroller, pre-programmed, KPA100
E610011
MISC
1
Socket for U1, 28 pins
E620011
U2 1 IC, octal peripheral driver, TD62083AP (alt: ULN2803)
E600040
U3 1 IC, 5-volt regulator, 78L05
E600029
U4 1 IC, RS-232 driver/receiver, MAX1406CPE (alt: LT1039CN16)
E600036
U5 1 IC, dual op-amp, LM358AN
E600010
U6 1 IC, high-current op-amp w/enable, EL5146CN
E600041
U7 1 IC, dual op-amp, rail-to-rail, LMC6482AIN
E600011
X1 1 Crystal, 18.432 MHz, low profile ("S184ECSL")
E660019
X2 1 Crystal, 4 MHz ("4.00-20")
E660006
Z1 2 Ferrite beads, 0.23" (6 mm) long; two beads on a 1N4007 diode lead)
E980029
10
Picture
Ref. Designator(s)
QTY
Description
Part #
HDWR
2
Fuse holder housing, twist-lock (for external 20A fuse)
E980047
HDWR
2
Fuse holder contacts, #12 size
E980048
HDWR
1
Fuse holder spring, for 1.25" long fuse
E980049
HDWR
2
Fuse, 20A, Littlefuse #312020 or equivalent (1 spare)
E980050 HDWR
2
Jackscrew, 4-40, hex (for J8)
E700078
HDWR
5
Standoff, 3/16 dia. x 3/16" long hex 4-40 thd (between PCB and heat sink)
E700068
HDWR
2
Standoff, 3/16 dia. x 1/2" long hex 4-40 thd (between PCB and shield)
E700061
HDWR
5
Standoff, 3/16 dia. x 5/8" long hex 4-40 thd (between PCB and shield)
E700060
HDWR
20
Screw, 4-40 x 3/16" pan head, black oxide (2 spares)
E700015
HDWR
5
Screw, 4-40 x 3/16" undercut flathead, black oxide (1 spare)
E700025
HDWR
19
Screw, 4-40 x 1/4" panhead (2 spares)
E700005
HDWR
3
Screw, 4-40 x 1/4" flathead (1 spare)
E700063
HDWR
5
Screw, 4-40 x 11/16” flathead
E700199
HDWR
8
Set screw, 4-40 x 1/2", .05" hex socket head, stainless steel (1 spare)
E700066
HDWR
15
Nut, 4-40 small pattern (2 spares)
E700055
HDWR
1
Nut, 6-32 hex, stainless steel (for GND screw)
E700069
HDWR
36
Lock washer, #4 split (3 spares)
E700004
HDWR
2
Flat washer, #6, Stainless Steel
E700067
HDWR
3
Spring clip (used on shield)
Note: Illustration at left shows side and front views of clip.
E980058 HDWR
3
Solder lug (used for grounding J2)
E700062
HDWR
1
Thumbscrew, 6-32 x 1/2", black plastic knob (for GND screw, E1)
E700070 HDWR
5
Fiber washer for speaker, #4, .047" thick x 0.25" dia. (1 spare)
E700028
11
Picture
Ref. Designator(s)
QTY
Description
Part #
MISC
1
Heat sink, KPA100, approx. 7.6" W x 6" L (19.23 x 15.2 cm)
E100127
MISC
1
PC board, KPA100
E100134
MISC
1
Top cover trim panel, KPA100, painted (wrapped in paper)
E100135
MISC
1
Rear panel, KPA100, painted and silk-screened (wrapped in paper)
E100136
MISC
1
Shield, KPA100, approx. 7.3" W x 6" L (18.5 x 15.2 cm)
E100137
MISC
1
Speaker shield, 1.9" diameter (4.8 cm), with self-adhesive pad on inside
E980087
MISC
1
Grille cloth, black, approx. 3 x 3" (7.5 x 7.5 cm)
E980053
MISC
2
Thermal pad for flange-mount power transistor (Q1 and Q2)
E980051
MISC
2
TO-126 thermal pad, self-adhesive (Q3, Q4)
E980052 MISC
1
BNC connector cap, plastic (to cap K2's BNC antenna jack)
E980006
MISC
26 ft.
Enamel wire, #22 red (for all low pass filter toroids)
E760018
MISC
9 ft.
Enamel wire, #26 red (for T3, T4, L16)
E760002
MISC
3 ft.
Enamel wire, #26 green (for T3 and T4)
E760004
MISC
5 ft.
2-conductor wire, #12 stranded, red/black (for DC power wiring)
E760033
MISC
1 ft.
RG174 coax (for RF cable to K2 RF board)
E760010
MISC
1
10-conductor ribbon cable with pre-installed connectors; 4" long
E980045
MISC
1 ft.
2-conductor speaker cable, #24 stranded (for J5 and speaker)
E760012
MISC
10 ft.
4-conductor shielded cable (serial I/O cable)
E760009
MISC
1 ft.
Stranded insulated hookup wire, #20 black (for DC cable to K2 RF board)
E760006
MISC
1 ft.
Stranded insulated hookup wire, #20 red (for DC cable to K2 RF board)
E760007
12
Picture
Ref. Designator(s)
QTY
Description
Part #
MISC
1 ft.
Hookup wire, #24, solid conductor, green ins. (for K2 Control board mod)
E760008
MISC
1 ft.
Stranded, Teflon-insulated wire, #22 gray (for T1)
E760020
MISC
2 ft.
Stranded, Teflon-insulated wire, #18 gray (for T2)
E760021
MISC
3
Cable tie, 3"
E980002
MISC
1
Allen wrench, .05", short handled (for 1/2" heat sink set screws)
E980008
MISC
1
Sand paper, 180-grit (for heat sink preparation)
E850090
13
Assembly, Part I
Place the KPA100 PC board as shown in Figure 1, and identify the top side, which has most of the components. (A complete parts placement drawing can be found at the end of this appendix.) The "Front Edge" and "Back Edge" designations are based on the board's orientation when installed in the K2.
(Top Side)
KPA100 REV A
Front Edge
J7
J3
J6
J8
Back Edge
Figure 1
With the bottom side of the board facing you (speaker cutout at the
upper right), locate the position for resistor R28, along the back edge, far right. The label "R28" is just above of the resistor’s outline.
Install a 200-ohm, 1-watt resistor (red-black-brown) or (201J)
at R28. Form the leads to fit the given pad spacing. Bend the leads to hold the resistor in place. Note: It's a good idea to orient all resistors in one direction for ease in reading the color codes later. If R28 has color bands, orient it with the first color band (red) toward the left.
Make sure R28 is seated flat on the board, with no excess lead length exposed. This is necessary to keep the resistor from touching the heat sink, which will be attached later.
i
The use of acid-core solder, water-soluble flux solder, or any corrosive or conductive flux or solvent will void your K2's warranty. Also avoid "No-Clean" solder types, which may make board re-work more difficult. We recommend the use of Kester type 44 rosin core solder or similar. The residue from such solder need not be removed, since it is non-conductive. The use of cleaning solvents may damage the board or components.
Solder R28 from the top side of the board. Do not use an excessive
amount of solder. Trim the leads to about 1/16" (1.5 mm) or shorter.
i
If your solder joints are not clean and shiny, your iron may
not be hot enough, or you may be using the wrong type of solder. These "cold" solder joints will likely result in poor performance, reliability problems, or component failure. Before proceeding, consult our web site for additional soldering instructions and tool recommendations.
14
On the top side of the board, locate the component outline for .005-
ohm current-sensing resistor R7 (near the DC power connector, J3). Each of R7's pads has three holes.
Bend the leads of the .005-ohm, 3-watt resistor to match the spacing between R7s innermost pair of holes (see Figure 2a). Install the resistor, pressing it down onto the board as far as it will go.
On the bottom side, fold R7's leads outward so they lay flat against the pads (Figure 2b). Trim the leads to match the size of the pads. Solder each lead over the full length of the pad.
Note: Components may be soldered one at a time or in groups. Leads can be trimmed either before or after soldering. Flush trimming (trimming very close to the board) is required only when specified. Otherwise, trim leads to about 1/16" [1.5 mm] or less in length.
(a)
(b)
Figure 2
i
The leads on small capacitors are fragile. Do not pull on the
leads or bend them excessively.
Sort all capacitors into groups by capacitance value. Start by
grouping them by physical appearance (size, color, etc.).
In all cases where two or more capacitor types have the same value, further sort them by lead spacing and voltage rating. The parts list provides identification details for specific capacitor types.
Locate an 0.1- µF ("104") capacitor with 0.1" lead spacing for use at C75.
Install C75 at its indicated location on the bottom of the board, near the back edge. The capacitor must be seated as close to the board as possible, with 1/16" (3 mm) or less lead length exposed. Remove any U­shaped bends or folds using long-nose pliers. Solder C75 from the top side of the board.
Install a .01-µF ("103") capacitor with 0.1" lead spacing at C65. C65 is located on the bottom side of the board, near the front edge. Keep the lead length short, as described in the previous step.
15
The color bands on 1/4-watt 1% resistors can be difficult to read. Use a DMM (digital multimeter) to verify the values of all these resistors. Tape them to a piece of paper with their values labeled.
Install the resistors listed below on the top side of the board. Start with R3, which is at the front edge of the board, near the "KPA100" label.
In general, assembly proceeds from left to right and from front edge to back edge on the PC board.
__ R3, 2.7 ohms, 1/4 W (red-violet-gold) __ R24 and __ R25, 8.45 k, 1%, 1/4 W (gray-yellow-green-brown) __ R15 and __ R16, 3.3 k, 1/4 W (orange-orange-red) __ R31, 200 ohms, 1 W (red-black-brown) or (201J) __ R4, 100 k, 1/4 W (brown-black-yellow) __ R10, 47 ohms, 1/4 W (yellow-violet-black) __ R5, 15 k, 1/4 W (brown-green-orange) __ R8, 10 k, 1/4 W (brown-black-orange) __ R30, 3.09 k, 1% (orange-black-white-brown) __ R32, 100 ohms, 1%, 1/4 W (brown-black-black-black)
__ R14, 470 ohms, 1 W (YEL-VIO-BRN) (located near back edge) __ R11, 510 k, 1/4 W (green-brown-yellow) __ R13, 100 ohms, 3 watts __ R1, 3.3 k, 1/4 W (orange-orange-red) __ R2, 2.7 ohms, 1/4 W (red-violet-gold) __ R29, 3.3 k, 1/4 W (orange-orange-red), location: far left, near small notch
Sort all of the RF chokes by size and value. Do not pull on the leads, which are fragile and can be easily damaged.
Locate a small 100-µH RF choke for use at RFC11 (BRN-BLK­BRN color code, 0.4" lead spacing). Do not use one of the miniature 100­µH RF chokes, which has a much smaller lead spacing.
Install RFC11 on the bottom side of the board. Its location is close to the cutout for power transistor Q1.
Make sure RFC11 is pressed against the board as far as it will go, then solder it from the top side of the board.
Install and solder the RF chokes listed below. Limit soldering time on miniature chokes (2 to 3 seconds per lead). All chokes are on the top side of the board near connectors J3 and J8. The body of RFC9 is slightly longer than the spacing of the solder pads on the board. Bend the leads under the body of RFC9 as needed to pass through the pads. RFC9 will stand slightly above the board. That is normal.
__ RFC9, 15 µH, miniature (brown-green-black) __ RFC6, __ RFC7, __ RFC8, 100 µH, miniature (brown-black-brown) __ RFC4, __ RFC5, 15 µH, small (brown-green-black)
Locate miniature choke RFC3, 100 µH (brown-black-brown) and resistor R33, 1k, 1/4 watt (brown-black-red).
Bend the leads of RFC3 to fit the pads on the board, but do not install it yet.
Mount resistor R33 on top of choke RFC3 as shown in Figure 3. Wrap each resistor lead around the RFC lead next to its body once and solder. Keep the soldering time short to avoid damaging the choke.
RFC3
R33
Wrap and Solder at Both Ends
Figure 3
Install the R33/RFC3 pair in the location marked RFC3 with the choke against the board and the resistor above it. Solder and trim the leads.
16
Check the resistance across each RF choke using the lowest resistance scale of your DMM. This will ensure that the chokes were not damaged during soldering. All readings should be under 10 ohms.
Sort all of the diodes according to type. Use a magnifying glass if necessary to positively identify glass diodes (1N4148 and 1N5711).
Install diodes D1-D8 (1N4148) on the bottom side of the board, near the large cutout, but do not solder yet. Bend the leads very close to the body to fit the given pad spacing. The banded end of each diode (cathode) must be aligned with the band on its component outline.
Make sure D1-D8 are seated as far down on the PC board as possible. Solder and trim the leads.
i
When installing the diodes in the next step, save the trimmed 1N4007 leads in a small labeled bag for use as jumpers, etc., in later steps.
Install the remaining diodes on the top side of the board. Start with
D17, at the lower left-hand corner near the small notch.
__ D17, 1N5711 __ D16, 1N5711 __ D10, 1N5404 __ D13, 1N5404
Note: D14, 12, and 11 are not all oriented in the same direction
__ D14, 1N4007 __ D12, 1N4007 __ D11, 1N4007
__ D9, SB530
Using the diode check scale on your DMM, test all of the diodes on the board. (This will ensure that diodes have not been damaged during installation.) First, touch the red (+) lead of the DMM to the anode (non­banded end), and the black (-) lead to the cathode (banded end); the meter should indicate a forward voltage in the range of 0.1 to 0.7 volts, varying with diode type. Next, reverse the leads; the DMM should show an open­circuit indication (flashing "3.000" or "0.000," etc.).
Near the "ELECRAFT" label, you’ll find a short jumper location,
identified by a ground symbol ( ). Use a saved 1N4007 diode lead to make a 3/4" (19 mm) U-shaped wire for this jumper. Mount the jumper on the top side of the board, with the top of the U-shape approx. 1/4" (6 mm) above the board. Solder it from the bottom side.
Install the following capacitors on the bottom side of the PC board,
but do not solder yet. Capacitors must be seated as close to the board as possible. About 1/16" (3 mm) of lead length may remain exposed. Remove any U-shaped bends or folds using long-nose pliers.
Note: These capacitors are all .01 µF (103), with 0.1" lead spacing.
__ C99 __ C97 __ C98 __ C22 __ C74 __ C29 __ C13 __ C15 __ C17 __ C19 __ C21 __ C14 __ C16 __ C18 __ C20
Use a ruler to check the height of all capacitors just installed, as well as C65 (near the front edge) and C75 (near the back edge). If any capacitor body extends to 3/16" (4.5 mm) or more above the surface of the board, fold it down toward the board. The capacitors should not touch any adjacent pads.
Solder the capacitors from the top side. Use just enough solder to
fill the hole, since the leads will be flush-trimmed in the next step.
i
Important: Relays K1-K12 will be installed on the top side of
the board, opposite capacitors C13-C22 and C29. This requires that the capacitor leads and their surrounding solder filets be trimmed as close to the PC board as possible.
Flush-trim the leads of C13-C22 and C29 on the top side of the board. After trimming, the leads and surrounding solder filets should be no more than 1/32" (0.8 mm) high.
17
Install the 0.2" lead spacing capacitors listed below on the top side
of the board. Start with C11, which is along the front edge of the board near the "KPA100" label.
__ C11, 0.1 µF (104) __ C23, 0.1 µF (104) __ C25, .001 µF (102) __ C68, .01 µF (103) __ C89, .01 µF (103)
__ C26, 33 pF, 50V (Do not confuse with C5F, rated at 500 V or 1 KV) __ C41, 100 pF (101)
__ C38, .01 µF (103) __ C39, .01 µF (103) __ C37, .01 µF (103) __ C36, 0.015 µF (153, 15N) __ C35, 0.1 µF (104) __ C44, .01 µF (103) __ C42, 0.015 µF (153, 15N) __ C43, 0.015 µF (153, 15N) __ C46, .01 µF (103) __ C40, 0.1 µF (104)
Place relays at locations K1-K12, excluding K3. (K3 will be installed after the output transformer, T2.) Each relay can only be installed one way; the white mark on the relay must be oriented as indicated by the mark on the component outline. Do not solder the relays yet, and do not clip or bend the relay leads.
Inspect each relay to make sure that it is seated flat against the board. If not, remove it and flush-trim the leads which are preventing it from sitting flat against the board.
Make sure that you have not installed relay K3.
Using a hardcover book or other flat object to hold the relays in place on the top side of the board, flip the board over. Solder two diagonal corner pins on each relay.
Inspect the 11 relays closely to make sure that they’re seated flat against the PC board. If not, re-heat the corner pins one a time while pressing down on the relay. Once all relays are properly seated, solder the remaining pins. Do not trim relay leads, which can cause mechanical
stress, reducing the life of the relay.
Install resistor network RP1 near the "KPA100" label at the front edge of the board. The dotted (pin 1) end of RP1 should be oriented to the left. (RP1 is symmetrical and can be reversed, but this orientation will help visually identify the pin 1 end.)
Install trimmer potentiometers R26 and R27 (100 k, "104") near the speaker cutout. The trimmers will sit a small distance above the PC board on the pin shoulders. Set the trimmers to their midpoints.
Install trimmer potentiometer R6 (1 k, "102") at the right side of the board near T1. Set the trimmer fully counter-clockwise.
Install the ceramic trimmer capacitors, C1 and C27. C1 is supplied in a separate envelope and C27 is loose in the bag.. Orient the flat side of each trimmer as shown below:
__ Install C1 (white). The location for C1 is at the far left near the small notch.
__ Install C27 (yellow). The location for C27 is near the microcontroller, U1 (16F872).
Using a small flat-blade screwdriver, set both trimmers to their midpoints (screwdriver slot perpendicular to the flat side as shown above).
18
Install the small capacitors listed below. (The first capacitor in the
list, C50, is near trimmer C27). Lead spacing (LS) and voltage are shown where required to identify the capacitor type.
__ C50, .01 µF (103), 0.1" LS __ C30, 0.1 µF (104), 0.1" LS __ C33, 0.1 µF (104), 0.1" LS __ C34, 0.1 µF (104), 0.1" LS __ C61, .047 µF (473) __ C62, .047 µF (473) __ C63, .047 µF (473) __ C70, .001 µF (102), 0.2" LS __ C69, .001 µF (102), 0.2" LS __ C55, .047 µF (473) __ C56, .047 µF (473) __ C57, .047 µF (473)
__ C54, .047 µF (473) __ C53, .047 µF (473) __ C52, .047 µF (473) __ C49, .047 µF (473) __ C48, .047 µF (473) __ C31, .22 µF (µ22J63) __ C86, .0047 µF (472) 0.2”LS __ C76, .01 µF (103), 0.1" LS __ C67, .0047 µF (472) 0.2”LS __ C77, .015 µF (153, 15N)
__ C66, 180 pF (181)
__ C28 .01 µF (103), 0.1" LS (far left side of the board near K4) __ C12, .01 µF (103), 0.1" LS
__ C95, 100 pF (101) (near small notch and T4)
__ C88, .001 µF (102), 0.2" LS __ C87, .001 µF (102), 0.2" LS __ C24, .01 µF (103), 0.1" LS __ C85, .047 µF (473) __ C90, .01 µF (103), 0.2" LS __ C71, .0018 µF (182), 0.2" LS __ C72, .01 µF (103), 0.1" LS __ C73, .01 µF (103), 0.1" LS
__ C10, 0.1 µF (104), 0.2" LS __ C32, .01 µF (103), 0.1" LS __ C7, .01 µF (103), 0.1" LS __ C8, .01 µF (103), 0.1" LS __ C9, .01 µF (103), 0.1" LS __ C84, .001 µF (102), 0.1" LS
Install the low-pass filter capacitors listed below. All are 500 V or 1KV (1000 V) disc, with 0.2" lead spacing. These capacitors are located on the left side of the board between the two rows of relays (K3-K12).
Note: Some of these capacitors are arranged in close-spaced groups of three on the board. Look at all of the reference designators in a group to be sure you know which capacitors they refer to.
__ C5B, 18 pF (may have black band on top and no marked voltage) __ C3B, and __ C4B, 27 pF __ C5F, 33 pF (Do not confuse with C26, which is 33 pF, 50 volts) __ C3H, 39 pF __ C5D, 47 pF __ C4D, 56 pF (may have black band on top and no marked voltage) __ C5A, 68 pF __ C6C, 68 pF (Note: C6D pertains to the large cap to the left of C6C) __ C3E, and __ C5G, 82 pF __ C4E, 120 pF (121) __ C3G, __ C4A, __ C5C, __ C5E, and __ C6E, 150 pF (151) __ C2B, __ C3C, and __ C3J, 220 pF (221) __ C3A, __ C3D, __ C4C, and __ C6F, 270 pF (271) __ C3F, __ C6A, __ C6B, and __ C6G, 330 pF (331) __ C2D, 390 pF (391)
Install a .0047 µF capacitor, C79 (0.4" lead spacing, "4n7J250"). C79 is located near relay K2.
Install a .0047 µF ("4n7J250") capacitor with 0.4" lead spacing at C64. C64 is located near relay K2.
Install the electrolytic capacitors, C51 and C60. C51 (470 µF) is near the large transformer, T2. C60 (100 µF) is near T1. The (+) lead must be installed in the hole marked with a "+". The (+) lead is usually longer than the (–) lead, and the (–) lead is identified by a black or white stripe.
19
Install the low-profile 18.432 MHz crystal ("S184ECSL") at X1, near the speaker cutout. Make sure the crystal is seated flat against the board, then solder. Use a minimum amount of solder to avoid a short under the can. Note: Insulators are not needed for crystals. The solder mask on the top of the board provides adequate insulation.
Install the 4 MHz crystal (X2) near the microcontroller (U1). Use minimal solder. Excess solder may short the lead to the case under the crystal. X2 must be seated flat against the board, with no insulators
or other spacers under it, or the metal shield will not fit correctly.
Cut two 3/4" (19 mm) bare wires (use small component leads). Insert a bare wire into the grounding hole provided just to the left of
X2. Solder this wire to the side of the crystal can, not the top, or it will prevent installation of the shield in a later step. Keep soldering time below 5 seconds; if it takes longer, your iron may not be hot enough, or your iron tip may not be making good contact with the crystal can.
Turn the board over, then solder and trim X2's ground wire.
Ground crystal X1 using the second bare wire. X1 is low profile, so the wire can be soldered to the top of the can. Avoid overheating. It may help to pre-tin the crystal can before attaching the ground wire.
Install the 10-pin, dual-row (5x2) male connector at P1, but do not solder yet. Figure 4 shows P1 as viewed from right side of the board. The plastic part of the connector must be on the top side of the board, with the long end of the pins pointed up. The short ends are inserted into the board.
P1
Figure 4
Solder just one pin of P1, from the bottom side. Note: P1's plastic body can melt if too much heat is applied, causing the pins to be mis­positioned. Limit soldering time to 2 to 3 seconds.
Examine the placement of P1. If it is not flat against the board, re-
heat the soldered pin while pressing down on the connector.
Once P1 is in the right position, solder the remaining pins. Do not
trim the leads.
Install a 2N3904 transistor at Q8, near X1. (Use a magnifying glass
if necessary to identify TO-92 package transistors.) The flat side of the transistor must be oriented toward the flat side of its outline as shown in Figure 5a.
Figure 5
Install another 2N3904 at Q5, which is on the right side of the board
near potentiometer R6 (labeled "BIAS SET").
Install voltage regulator U3 (78L05), which has a 3-lead TO-92 package like the 2N3904 transistor. U3 is located in the right-front corner of the board near connector P1.
i
The MOSFET transistors to be installed in the following steps can be easily damaged by static discharge. Before and during installation of these devices, touch an unpainted, grounded metal surface.
Install MOSFET transistors Q10, Q11, Q12 (2N7000), which are located near the "KPA100" label. The flat side of each transistor must be aligned with the flat side of its outline as shown in Figure 5a.
20
MOSFET transistors Q6 and Q7 (ZVN4424) have a modified TO-92 package that must be oriented as shown in Figure 5b. Some ZVN4424's may be labeled on both sides, so you'll need to go by the shape of the part: orient the larger flat side toward the flat side of the outline. Install and solder Q6 and Q7, which are located between relays K1 and K2.
Q9 is a TO-220 package MOSFET (IRF830 or IRL620) with a metal tab. The tab may have been cut off already. If not, you'll need to trim it. Using heavy wire cutters or tin snips, cut off most of the tab (see Figure
6). This is necessary to prevent the tab from shorting to the shield in later steps. Do not use flush cutters or other small cutting tools to cut off
the tab; this may damage the tool.
Install Q9 vertically as shown below. The transistor will sit above the board due to the shoulders on the leads. The tab must be oriented toward J7 as indicated by the component outline. Trim the pins on the bottom after soldering.
Shortened Tab
Back edge of PCB
Figure 6
Transistor Q3 (MJE182) will be installed on the bottom side of the
board, near the board cutout for power transistor Q2. Place the transistor over its outline, with the metal side of the package facing away from the board. Bend the three leads at right angles to match the given pad locations, but do not solder yet. Note: the leads will break if bent too many times.
Insert Q3's leads into their holes. Center the transistor's plastic body
within its component outline. Re-form the leads if necessary.
Verify that Q3's metal side is facing away from the board, then
solder the leads from the top side, keeping the transistor pressed down against the board.
Install Q4 in the same manner. Locate R40, a 22K 1/4 W resistor (red-red-orange).
Make a 1/4” (6.3 mm) length of insulation by stripping a short segment from one end of the red or black #20 insulated wire. Don’t use the green #22. That insulation is too small.
Slide the insulation over one lead of R40 and position it against the body of the resistor.
21
Mount R40 on the bottom of the PCB as shown in Figure 7. There is no outline on the board for this resistor. Study the traces carefully to be sure you have it positioned correctly. Position the resistor against the board. The insulation is to ensure the bare lead cannot short to any of the traces. If necessary trim the insulation slightly if it is too long. Solder to the existing solder pads that are already occupied by leads. Trim the resistor leads short so no excess lead extends beyond the solder.
2
2
K
Insulate exposed
lead (see text)
Enlarged
area
Bottom
of board
Figure 7
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Before handling ICs, touch a metal surface. ICs damaged by electrostatic discharge can become intermittent, and the resulting problems may be difficult to troubleshoot.
Note: The pin 1 end of ICs can be identified by a notch or dimple as
shown in Figure 8. This end must be oriented toward the notched end of the component outline.
Pin 1
Notch
Pin 1
Dimple
Figure 8
Install U5 (LM358, 8 pins), which is located on the top side of the
board, left of the "KPA100" label. A portion of the part number is printed on the board under the IC ("358"). Do not solder yet.
Bend two opposite corner pins on the bottom side to hold the IC in
place. Solder all 8 pins (about 1 to 2 seconds per pin).
Install the ICs listed below. All are located to the right of U5. Compare the part number on the IC to the number printed on the board, and make sure that the pin 1 end is oriented correctly.
__ U2, TD62083 __ U6, EL5146 __ U4, MAX1406 __ U7, LMC6482
Install the 28-pin IC socket at U1. The notched end of the socket must be aligned with the notched end of its outline.
22
i
In the following steps you'll be installing several connectors at the back edge of the PC board (top side). These connectors must be installed correctly in order for the rear panel to fit onto the PC board. Figure 33 (page 42) shows how the rear-panel connectors will
appear once installed.
Install the external speaker jack, J6, at the back edge of the board.
Solder the center pin only. Make sure that the jack is pressed down flat against the board while soldering.
If J6 does not appear to be aligned with its PC board outline, or it is tilted, re-heat the center pin while adjusting the connector's position. Once it is positioned correctly, solder the other two pins.
Locate screw terminal E1. If it was supplied with a screw, remove it. The screw will not be used.
Place E1 in its indicated position, with the threaded hole facing the rear edge of the board. Solder just one pin. CAUTION: This part will get hot; don’t touch it with your finger while soldering.
If necessary, reheat the soldered pin of E1 and adjust it so that all four pins are pressed down on the board as far as they'll go. Then solder all pins.
Install the RCA jack, J7. The small plastic standoffs on the bottom of the connector should be inserted in the holes provided. While soldering, hold J7 flat against the board, and keep it centered within its component outline. Clip the leads on the bottom side.
Locate J8, the 9-pin "D" connector, and temporarily place it in its indicated location (far right side of the board). Note that the leads of capacitors C97-C99 on the bottom of the board interfere with the proper seating of J8. To avoid this, you will need to trim off the plastic extensions on both sides of the connector. First, bend upward and cut off the thin metal tabs above the plastic extensions (do not use flush cutters for this--you may damage them) . Then trim the plastic away so that it doesn't interfere with the leads of C97-C99.
Install J8 and solder just one of the 9 pins. Adjust the position of J8 as you did for the other connectors, making sure the connector is flat against the board. Then solder the remaining pins.
i
You may have received two 16F872 microcontrollers with your kit. The one marked "KPA100" or "PA" should be used here. Before handling U1 (16F872), touch a grounded surface.
Straighten the leads of U1 (PIC16F872) as shown below. The rows of pins must be straight and parallel to each other to establish the proper pin spacing. To straighten the pins, rest one row of pins against a hard, flat surface. Press down gently on the other row of pins and rock the IC forward to bend the pins into position as shown below.
Straight
Flared
Figure 9
Insert U1 into its socket, with the notched or dimpled end of the IC aligned with the notched end of its component outline.
Examine U1 closely. If any pins are bent, remove the IC and straighten them. (To remove U1 from its socket, pry it up gently on each end using a small flat-blade screwdriver.)
23
Visual Inspection
i
Nearly all problems with kits are caused by poorly-soldered
component leads or incorrectly-installed components. You can locate and correct most assembly errors ahead of time with a simple visual inspection. This is especially important at high power levels, where an unsoldered or reversed component could cause damage to the power transistors.
Verify that there are no parts installed at the following locations (In addition to the following, there are other open spaces where parts will be installed later as well) :
C82. C83 (capacitor is mounted on the top of transformer T2). L15. R12.
Using a magnifying glass, examine the bottom of the PC board closely for all of the following: cold solder joints (dull rather than shiny appearance), solder bridges, and leads that are not soldered. Re-heat any suspect joints.
Using the parts placement drawing at the end of the appendix, re-check the orientation of all:
Diodes Transistors ICs
Initial Tests
Make the resistance measurements listed below, touching the DMM's (+) and (-) leads to the indicated points. The (-) lead will go to ground in all cases except the first measurement (relay coils).
i
The symbol > means greater than. Your DMM may indicate
infinite resistance (all digits flashing) for readings that are listed as "> 10 k." (Do not use an analog VOM.) Other readings should be +/- 10 %. K4 reads higher resistance than the other relays because K3 is not yet installed (the two coils are in parallel).
KPA100 Test Points (+, -)
Resistance
(+) and (-) leads of relays K1,K2,K4-K12
(on bottom of board, marked)
650-800 (K4)
325-400 (others)
U1 pin 1, ground
> 1 k
U1 pin 2, ground
> 10 k
U1 pin 3, ground
> 10 k
U1 pin 4, ground
3.1 k
U1 pin 13, ground
> 10 k
U1 pin 14, ground
> 10 k
U1 pin 27, ground
> 10 k
U1 pin 28, ground
> 10 k
U4 pin 1, ground
> 10 k
U4 pin 8, ground
> 10 k
"AF" pad (measure from bottom), ground
> 10 k
D10 banded end, ground
> 10 k
Determine what revision of firmware your K2 has installed at present by turning the K2 on while holding any switch. Record the number shown at the left end of the LCD (e.g., 2.01H): _______.
Turn off the K2. Disconnect all external cables.
Remove the six K2 top cover screws shown in Figure 10.
Remove the top cover. Disconnect the speaker and all options.
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