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-   -   Commercial Gainclone kit- building instructions (http://www.diyaudio.com/forums/audio-sector/123003-commercial-gainclone-kit-building-instructions.html)

Peter Daniel 13th May 2008 03:29 PM

Commercial Gainclone kit- building instructions
 
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This thread idea started here: http://www.diyaudio.com/forums/showt...69#post1500369 and is aimed to provide guidance in building a simple Gainclone amp.

While I'll be using as an example a commercial kit, there is nothing wrong with wiring the circuit point to point, without using printed board.

If commercial forum section is more appropriate for this subject, please move it there.

The basic kit contains printed board, 2 LM3875 chips, 8 resistors, 4 main filter capacitors and 16 diodes and is intended for dual mono application.

Peter Daniel 13th May 2008 03:44 PM

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The boards have scoring lines separating amp and power supply sections, for now break them in half only, as it will simplify assembly.

Peter Daniel 13th May 2008 03:48 PM

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The amp basic schematic shows only 4 resistors per channel.
R1 is optional and its value can be anything between 200R and 1k (or so). I usually don't install that resistor at all, placing piece of wire in its place. Alternatively, if you need coupling capacitor to protect the amp from DC that may be produced by a source component, a small electrolytic cap can be installed here: 4.7uF or bigger.

Peter Daniel 13th May 2008 03:58 PM

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Identifying resistor values should not be a problem, as there are 4pcs that are 22k, 2 resistors are always longer, those would be 680R and the other two are 220R. You can also use a meter to check them out: it's good idea to choose out of four 22k, two that are close in value and use them for feedback (in place of Rf)

A resistor color band conversion table is attached.

Peter Daniel 13th May 2008 04:09 PM

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The power supply section consists of 8 diodes per channel (we are discussing dual mono kit for now) and optional two small capacitors (10uF) which you may use, but they are not really required.

peranders 13th May 2008 04:21 PM

Quote:

Originally posted by Peter Daniel
Peranders, thanks for the input, but I prefer to do things my way.
I know that... :)

Peter Daniel 13th May 2008 04:23 PM

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Since we covered the content of the kit, we can start soldering.

I usually use Kester rosing core solder, 0.020 (SN63PB37). For bigger jobs 0.031 is preferrable. I also use Wonder Solder for some specific projects.

If I can recommend one tool that is really helpful, it would be solder dispenser available from percyaudio.com . It is especially useful when both hands are busy and you need to use mouth to feed the solder.

As to soldering gun, a 40W would be maximum for such project and 25W more suitable.

I have 3 Hakko stations that simplify task, but for a beginner this is not needed.

Peter Daniel 13th May 2008 04:46 PM

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I start with resistors, a set of tweezers is useful in forming leads and placing the parts, but not neccessary.

Peter Daniel 13th May 2008 04:50 PM

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A close up, so you can't go wrong ;)

Peter Daniel 13th May 2008 05:23 PM

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When soldering, place the tip of the iron on the pad and component pin and slowly feed the solder untill nice joint is formed.


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