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CA-0252-DIY Rev A ~ Discrete Opamp Pictorial Build Guide |
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MAKE SURE the build guide you follow matches the Revision of the PCB you are building!
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Preface
The CA-0252-DIY Rev A ~ Discrete Opamp Pictorial Build Guide is written with the intermediate builder in mind. If you have
successfully built another kit or two and have good soldering skills, you should be fine.
FYI, I do not suggest testing a freshly built opamp with a freshly built module. If things are not working right, you will
have no way of knowing if it is the opamp or the module.
BOM (Bill Of Materials)
CA-0252-DIY Rev A PCB BOM
[Last upload 4/4/2020]
PCB Overlay
CA-0252-DIY Rev A Overlay
[Last upload 4/5/2020]
Schematic
The schematic for the CA-0252 is not published.
Support Thread
CA-0252-DIY Rev A ~ Discrete Opamp [Build] support thread at groupdiy.com
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2.A.1 |
Use this Resistor Sorting Chart to help keep your parts straight.
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2.A.2 |
Properly identifying and sorting the resistors is very important. This task can be done many ways. If you wanna
roll old school, click the pic to the left to download my Resistor Color Code Chart. Pay special attention to distinguish
the difference between values like 390R and 3k9 as well as 470R and 47k! This is a common trap for the inexperienced. If
you are unsure about the color codes, PLEASE use a good DMM.
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2.A.3 |
The best way is to use a high quality DMM (digital multimeter) that has an Auto Range function.
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2.A.4 |
If your DMM has a Manual Range, make sure you have it set properly or you will get no reading or even a false reading.
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2.A.5 |
Note the different range settings used to identify the high value resistor.
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2.A.6 |
Once properly identified, all of the resisters can be bent over a small jeweler's screwdriver or similar. I like to
make sure the color codes ALL read from the top down. Keeping them consistent makes double checking your work later very
easy.
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2.A.7 |
Fairchild 1N914 diode, label is "91 4B"
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2.A.8 |
Bend all six 1N914 diodes over a small jeweler's screwdriver or similar, like we did with the resistors. I like to
keep ALL black bands indicating the cathode or negative end pointing upwards away from the PCB.
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2.C.1 |
A long conical tip for your soldering iron is invaluable for fine detailed work. We have a Hakko iron so we use the
T18-DL12
tip for it.
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2.C.2 |
Kester
24-6337-8807
small diameter no-clean solder is all we've been using for years. If you've never tried it, do so. It'll
change your life!
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2.C.3 |
We highly suggest
MicroCare VeriClean
No-Clean Flux Remover. Not only for this build but all of your PCB projects.
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3.0 |
And we begin with the customary blank canvas.
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3.1 |
I like to start with the components that are closest to the PCB. In this case its the ceramic capacitors. Using the BOM
for locations and values, install them now.
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3.2a |
If you haven't done so yet, bend all six 1N914 diodes over a small jeweler's screwdriver or similar. I like to
keep ALL black bands indicating the cathode or negative end pointing upwards away from the PCB.
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3.2b |
Install all of the diodes. Don't forget, the arrow in the silkscreen points to the end of the diode with the black
cathode band. Solder only from the bottom of the PCB.
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3.3a |
If you haven't done so yet, sort and identify all resistors. Bend resistors over a small jeweler's screwdriver or
similar. I like to make sure the color codes ALL read from the top down. Keeping them consistent makes double checking
your work later very easy.
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Click to enlarge
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3.3b |
I have grouped the resistors into 3 steps for maximum efficiency. Of course YMMV. Using the BOM for locations and values,
install R5, R13 and R15. Solder only from the bottom of the PCB.
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3.3c |
Using the BOM for locations and values, install R4, R6, R14, R16 and R17. Solder only from the bottom of the PCB.
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3.3d |
Using the BOM for locations and values, install all remains resistors. Solder only from the bottom of the PCB.
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3.3e |
Double check your work.
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3.3f |
And also double check from this angle.
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3.4a |
Slip the TO-39 spacers over the leads of each metal can output transistor. The little bumps in the spacers will be away
from the transistors so they will be resting on the PCB.
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3.4b |
Install the output transistors in their respective locations. Make absolute sure the label on the can matches the part
location on the BOM. For an extra precaution, the component values are also on the PCB silkscreen. THESE PARTS ARE NOT
INTERCHANGEABLE SO DO NOT SWAP THEM AROUND!! I like to alternate devices while soldering as to not heat up a part more
than necessary.
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3.4c |
Double check to make sure you have the output transistors in their proper places.
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3.5a |
Inspect the TO-92 transistors. If any of them have their middle lead kinked backwards, we will have to deal with that.
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3.5b |
You can easily straighten a kinked middle lead with the flat area of any pliers.
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3.5c |
If the outer leads are not kinked to .1" centers, slightly bend them outwards.
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3.5d |
Using the BOM for locations and values, install Q4, Q5 and Q9. If the leads are kinked to .1" centers they will drop
right in. If they are straight, slightly bend them outwards as mentioned in the last step. Insert them and gently wiggle
side to side while pressing downwards. Push in so they approximately match the height of all other components on the
board. Solder only from the bottom of the PCB, alternating between parts to not overheat anything.
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3.5e |
Using the BOM for locations and values, install Q6 and Q7. Solder only from the bottom of the PCB, alternating between
parts to not overheat anything.
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3.5f |
Using the BOM for locations and values, install Q1, Q2 and Q3. Solder only from the bottom of the PCB, alternating between
parts to not overheat anything.
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3.5g |
The heights of all TO-39 transistors should be very much similar to the other components already installed on the board.
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3.6a |
Affix the PCB assembly in a clamp or fixture so it sits bottom side up, flat and level.
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3.6b |
Insert a terminal pin while keeping it slightly elevated off of the PCB with your soldering iron tip between the PCB and
the terminal pin's collar.
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3.6c |
Apply solder but don't over do it and make a mess on the pin.
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3.6d |
Gently press down on the terminal pin's collar so it seats fully in the PCB. Double check from two directions that the
pin is fully perpendicular to the PCB.
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3.6e |
Rinse and repeat for the four remaining pins. There is no circuit connection to 0V Common so that pin is not on our build.
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3.6f |
If the proper soldering technique is used, there is absolutely no need to try and solder the terminal pins from the top.
The solder will flow thru to the top very nicely by following our tips. We've never had to solder one of these pins
from the top and we've built MANY!!
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3.7a |
Clean off any flux and solder residue as required. We use
MicroCare VeriClean
with a toothbrush and it is simply magical!
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3.7b |
Inspect the bottom of the PCB for solder bridges. There shalt be no solder bridges!!
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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 CA-0252-DIY Rev A ~ Discrete Opamp kit offered by Classic Audio Products, Inc.
Commercial use is prohibited.
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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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Curative Notice |
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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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