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CAPI DB25 Flexible PCB Style 2
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LC25-T LC40-T Rev A Pictorial Build Guide HEADING_TITLE
MAKE SURE the build guide you follow matches the Revision of the PCB you are building!

Table of Contents
1. Information, Documents & Downloads
2. Parts Identification
    A. Main PCB
    B. LC25 "GC" Gyrator Capacitors
    C. LC40 "GC" Gyrator Capacitors
    D. Other Parts

3. Main PCB Build
4. Switch PCB Build
5. Final Assembly
6. Copyright Notice and Disclaimer
 
1. Information, Documents & Downloads Back to Top
Preface
    The LC25-T LC40-T Rev A Pictorial Build Guide is written with the experienced builder in mind. Basic soldering and assembly skills are not covered here. Neither are basic resistor or capacitor sorting and identifying. Those skills are required and expected before attempting this build. I do not recommend this as a first build project. One of the simpler single stage preamps is a better place to start.

BOMs (Bill Of Materials)
  LC25-T Rev A.1_LC40-T Rev A_Main PCB BOM  [Last upload 9/24/2016]
  LC25-T Gyrator Rev A.1 BOM  [Last upload 9/24/2016]
  LC40-T Gyrator Rev A BOM  [Last upload 9/24/2016]
  LC25-40 Switch PCB Rev A.1 BOM  [Last upload 9/24/2016]
  LC25-40 Hardware BOM  [Last upload 9/24/2016]

PCB Overlays
  Overlay_LC25-T Rev A.1  [Last upload 9/24/2016]
  Overlay_LC40-T Rev A  [Last upload 9/24/2016]
  Overlay_LC25-40-SW Rev A.1  [Last upload 9/24/2016]

Support Thread
  LC25-T LC40-T Rev A [Build] support thread at groupdiy.com
 
2.A Parts Identification - Main PCB Back to Top
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2.A.0 The follow parts can be found in the Main PCB bag.
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2.A.1 Fairchild 1N914 diode, label is "91 4B"
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2.A.2 Fairchild 1N4004 diode, label is "1N4004"
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2.A.3 Fairchild 13V zener diode, label is "24 3B"
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2.A.4 Fairchild 4V3 zener diode, label is "4V3"
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2.A.5 Fairchild 2N3904 transistor, label is "2N 3904"
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2.A.6 Murata or BC 27pF ceramic capacitor, label is "27J" or "BC 27J"
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2.A.7 BC 68pF ceramic capacitor, label is "BC 68J"
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2.A.8 Murata or BC 82pF ceramic capacitor, label is "82J" or "BC 82J"
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2.A.9 BC 220pF ceramic capacitor, label is "BC 221"
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2.A.10 BC 1000pF ceramic capacitor, label is "BC 102"
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2.A.11 BC .1μF ceramic capacitor, label is "BC 104"
 
2.B Parts Identification - LC25 "GC" Gyrator Capacitors Back to Top
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2.B.0 The follow capacitors can be found in the LC25 Gyrator R's and C's ~ Inserts bag.
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2.B.1 Cornell Dubilier 120pF mica capacitor, label is "CDM 120"
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2.B.2 Cornell Dubilier 270pF mica capacitor, label is "CDM 270"
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2.B.3 Nichicon .001μF film capacitor, label is "102J"
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2.B.4 Nichicon .0015μF film capacitor, label is "152J"
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2.B.5 Nichicon .0022μF film capacitor, label is "222J"
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2.B.6 Nichicon .0047μF film capacitor, label is "472J"
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2.B.7 Panasonic .01μF film capacitor, label is "103J"
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2.B.8 Panasonic .018μF film capacitor, label is "183J"
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2.B.9 Panasonic .027μF film capacitor, label is "273J"
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2.B.10 Panasonic .033μF film capacitor, label is "333J"
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2.B.11 Panasonic .068μF film capacitor, label is "683J"
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2.B.12 Panasonic .15μF film capacitor, label is "154J"
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2.B.13 Panasonic .27μF film capacitor, label is "274J"
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2.B.14 Panasonic .56μF film capacitor, label is "564J"
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2.B.15 Panasonic 1μF film capacitor, label is "105J"
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2.B.16 Panasonic 1.8μF film capacitor, label is "185J"
 
2.C Parts Identification - LC40 "GC" Gyrator Capacitors Back to Top
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2.C.0 The follow capacitors can be found in the LC40 Gyrator R's and C's ~ Inserts bag.
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2.C.1 Cornell Dubilier 120pF mica capacitor, label is "CDM 120"
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2.C.2 Cornell Dubilier 270pF mica capacitor, label is "CDM 270"
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2.C.3 Nichicon .001μF film capacitor, label is "102J"
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2.C.4 Nichicon .0015μF film capacitor, label is "152J"
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2.C.5 Nichicon .0022μF film capacitor, label is "222J"
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2.C.6 Nichicon .0027μF film capacitor, label is "272J"
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2.C.7 Nichicon .0047μF film capacitor, label is "472J"
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2.C.8 Nichicon .0056μF film capacitor, label is "562J"
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2.C.9 Panasonic .01μF film capacitor, label is "103J"
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2.C.10 Panasonic .018μF film capacitor, label is "183J"
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2.C.11 Panasonic .022μF film capacitor, label is "223J"
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2.C.12 Panasonic .047μF film capacitor, label is "473J"
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2.C.13 Panasonic .082μF film capacitor, label is "823J"
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2.C.14 Panasonic .15μF film capacitor, label is "154J"
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2.C.15 Panasonic .33μF film capacitor, label is "334J"
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2.C.16 Panasonic .56μF film capacitor, label is "564J"
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2.C.17 Panasonic 1.2μF film capacitor, label is "125J"
 
2.D Parts Identification - Other Parts Back to Top
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2.D.0 Contains all parts for the switch PCB excluding the Grayhill switches.
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2.D.1 Contains the hardware bag, all Grahill switches and CAPI® control knobs.
 
3. Main PCB Build Back to Top
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3.0 The first task is to build the DTO5 opamp. Please visit the DTO5 build page and then return here.
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3.0a And we begin with a blank canvas.
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3.1 Identify and install the small package diodes.
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3.2 Locate and install all of the 10Ω power damping R's designated with PR.
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3.3 Identify and install all 1% .25W R's for the Main and RR sections of the PCB.
**Please note: the value of RR8 was not determined at the early part of this build so it is not installed in the build pics.
**Also note: RR1 was 59k in all of the build pics but was later changed to 100k when I finetuned RR8.
The values shown in the BOM are correct for both RR1 and RR8.
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3.4 Identify and install all gyrator R's. These are designated GR on the PCB.
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3.5 Install the large package diodes and the .5W R's. Save a cutoff lead from a diode for the next step.
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3.6 Bend the saved lead from step 5 over a small screwdriver tip and solder into the GND position. This is the preferred probe hook location for testing.
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3.7 Identify and install the small package ceramic capacitors.
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3.8 Identify and install the LME and TL0 opamps.
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3.9 Identify and install the five 4558 gyrator opamps.
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3.10 Install the two relays and then the 2N3904 transistor.
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3.10a Be extra careful not to short the close via to the adjacent 2N3904 pad!
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3.11 Identify and install all remaining capacitors for the Main and RR sections of the PCB.

3.12 Identify and install all gyrator capacitors for your specific build. These are designated GC. I changed my normal stuffing order in the four below pics to provide a better photo op.
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3.12a LC25 with half of the gyrator C's installed.
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3.12b LC25 with all of the gyrator C's installed.
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3.12c LC40 with half of the gyrator C's installed.
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3.12d LC40 with all of the gyrator C's installed.
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3.13 Install the 3-pin DC-Link shunt jumper header as well as the 7 and 11-pin receptacles that mate to the switch PCB. The 3-pin header and shunt can be found in the small hardware bag, which is inside the bag with the knobs and Grayhills.
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3.14 Install the six opamp sockets for A9. These should be installed thru and only soldered at the bottom of the PCB. The solder seen at the top has leaked thru during the process.
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3.15 Install the DTO5 opamp making sure it sits perpendicular to the main PCB.
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3.16 Prep for install of the EA2622 transformer. This step can be improvised. I use a small piece of foam tape that is only stuck to the PCB not the transformer. The goal is to slightly elevate the bottom of the can so it does not short with any of the pads. Foam tape is not included with the kit.
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3.16a Install the EA2622.
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3.16b Try and maintain an approximate 0.03" space between the bottom of the can and the PCB.
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3.17 Install the 2503 style output transformer following the 2503 hardware guide. I used the Litz version for these builds so I had to alter the lead's color code placement. For the Litz version, you can use this pic as a reference or follow the chart on the bottom left of the datasheet. For a standard EA2503, just match the lead's colors to their respective holes.
 
4. Switch PCB Build Back to Top
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4.0 And we again begin with a blank canvas.
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4.1 a. Install the 1N914 diode. Remember the black band on the diode goes to the PCB hole that the silkscreen arrow is pointing to. Bending the lead over a small screwdriver or probe tip is recommended.

b. Install all resistors. The bend cannot be too high or the lead may interfere with the L-bracket once you get to final assembly.
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4.2 Locate the ten Grayhill 56 series switches. Remove the nuts and put them to the side. Discard the lockwashers as we do not use them. The stop-pin has been factory set between positions 1 and 12.
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4.3 Loose fit the following six switches with no solder. SW3, 5, 6, 7, 9 and 11. Make sure the pin numbers on the switch's label sticker properly correspond to the silkscreen labels on the PCB.
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4.4 Carefully slide the switch PCB into the L-bracket. Make sure each and every switch's small collar fits evenly inside the corresponding hole in the L-bracket. Begin to install the panel nuts while continually holding the PCB in place. Finger tight for the nuts is fine for now.
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4.5 Install the remaining five panel nuts while continuing to pinch the PCB in place.
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4.6 Double check to make sure all six switches are flat and fully seated against the L-bracket.
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4.7 Before soldering, make sure the PCB is sitting parallel to L-bracket. The margin should be 0.03". Adjust as needed.
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4.8 Stand assembly up on the switch shafts. Solder two pins on each switch making sure the PCB is fully seated.

4.9 a. Finish soldering the rest of the switch pins while the assembly is still standing upwards. Alternating between switches is recommended to not overheat any of their innards.

b. Continue to leave the switch PCB fastened to the L-bracket.
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4.10 Install the four standoffs to the L-bracket with 3/16" undercut flat head screws. I use a nut driver on the standoffs which typically works so well that a screwdriver is not needed.
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4.11 Carefully insert the 90° headers into their respective receptacles orientated as shown.
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4.12 Gently slide the main PCB assembly into position on the L-bracket guiding the 90° header pins into their holes of the switch PCB.
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4.13 Install the four 3/16" pan head screws into the standoffs. Lockwashers are not needed at this time since its only temporary. The PCB hole size for these screws is very small so there should be little to no play or movement.
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4.14 Push the 90° headers against the switch PCB to make sure they are aligned properly and tight to the board.
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4.15 Carefully reach inside and solder two pins of each header at the top side of the switch PCB. A long narrow tip is required for this. Other methods can be used to properly install these headers but I have found this to be the easiest.

4.16 Break down the entire assembly by removing the six Grayhill nuts and the four 3/16" mounting screws. Gently unplug the switch PCB from the main PCB.
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4.17 Solder the remaining header pins at the top of the switch PCB.
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4.18 Make sure not to bridge the via to the adjacent header pin near SW4!
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4.19 a. Insert the four remaining Grayhill switches into their locations with no solder.

b. Insert the C&K toggle switch into the PCB with no solder. It is imperative that the flat of the switch bushing be properly orientated to the flat markings shown in the silkscreen.

c. Insert the three LED's into their locations with no solder. The silkscreen arrow points to the shorter cathode lead.
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4.20 Cut off approximately 3/8" of an inch from the leads of the Red BYPass LED.

4.21 Carefully insert the switch PCB assembly into the L-Bracket. Make sure the Grayhill switches fully seat into their mounting holes.
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4.22 a. Slip the faceplate into position.

b. Finger snug panel nuts on the four unsoldered Grayhill switches as well as two or three on the other side of the faceplate.
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4.23 a. Turn the assembly over and stand on the switch shafts.

b. The toggle switch should remain tight to the PCB and NOT fall against the L-Bracket.

c. Make sure all three LED's fall down and sit tight to the L-Bracket.

4.24 Solder all remaining pins and leads for the switch PCB.
 
5. Final Assembly Back to Top

5.1 Remove the switch nuts and disassemble the faceplate, L-Bracket and switch PCB.

5.2 Carefully plug the switch PCB into the main PCB.

5.3 Slide the entire PCB assembly into position on the L-Bracket for (hopefully) the last time.
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5.4 Secure the main PCB to the L-Bracket with the four 3/16" pan head screws. This time utilize the lockwashers.
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5.5 Slip the faceplate into position and secure with the ten Grayhill panel nuts. Use a 10mm socket and don't forget about console tape on the socket to prevent scratching up the faceplate!

5.6 Install the colored inserts on the ten CAPI control knobs.
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5.7a Using a thin piece of cardboard or similar as a spacer, begin installing the control knobs from the lowest frequency to the highest. The spacer is required to keep the knobs from dragging and rubbing on the panel nuts. Something around .02" thick works perfectly.
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5.7b Since we have not turned the switch shafts (you didn't did you?!), they will all be factory set in the -15dB position. Align the knobs accordingly and tighten with a .05" hex key.
 
6. Copyright Notice and Disclaimer Back to Top
The contents of this assembly guide page, including but not limited to all text, photographs and diagrams, is the intellectual property of Classic Audio Products, Inc. Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro-mechanical, is strictly prohibited under International Copyright laws. The sole purpose for this document is to aid in the assembly of the LC25-T LC40-T Rev A kit offered by Classic Audio Products, Inc. Commercial use is prohibited.
Classic Audio Products, Inc. is a DIY parts / kit retailer and provides no direct support for any of the products available on this site. Support for the kits can be found at the respective [Build] thread at groupdiy.com. Any support Classic Audio Products, Inc. chooses to provide, is provided "as is" without warranty of any kind. We cannot offer any guarantee as to the consequences of the support provided. Should the support cause damage or loss of any kind, Classic Audio Products, Inc. shall not be held liable to you or any other person for indirect, special, punitive, incidental, or consequential damages or losses. While the successful build rate is extremely high, there is no guaranteed favorable outcome. Always research and plan any project you undertake thoroughly. Sometimes, a project is over your head, and it just makes more sense to hire a qualified professional.
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Classic Audio Products, Inc. is not affiliated with API. Customers and fans should not refer to Classic Audio Products, Inc. as "Classic API." API is a registered trademark of Automated Processes Incorporated. Classic Audio Products, Inc. has no affiliation with Automated Processes Incorporated.
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