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PostPosted: 15 Oct 2010, 18:42 
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cmetzner wrote:
So, I was looking for directions more geared to an 8 yr old - such as "connect the cap to the hole that you connected the green wire to...".

Check out the first image in this thread: I found some Layout Software! (DIY Layout Creator).

It is a point-to-point layout of the K-12G. That should make it easier to follow along on your PCB. The schematic supplied with your kit should indicate the wire color code for the transformer. Sorry I can't help with the wire colors or PCB locations as I don't have that version.
Cheers

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PostPosted: 16 Oct 2010, 09:57 
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Thanks Gio, that is just what I needed.

-- Chuck


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PostPosted: 16 Oct 2010, 17:07 
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Gio wrote:
Check out the first image in this thread: I found some Layout Software! (DIY Layout Creator).

Sorry, I meant the second image, which shows the power supply. This should make it pretty clear for you.

K-12G Tube Amp Kit Schematic (click to enlarge)
Image

Voltsecond's C-RC Snubber Modification
The mods are shown on the VoltSecond page under the heading "HV Snubber Version 2, C-RC, Last update 20-Feb-05"
Attachment:
SPLIT_BOBBIN_SNUBBER_gr.gif


P2P Drawing of K-12G Tube Amp Power Supply (drawing shows Voltsecond's C-RC Snubber and Rectifier Modifications)
Attachment:
K-12G-Tube-Amp-Kit-Power-Supply.png

From the above you should be able to locate this portion of the circuit on the PCB.


Note the the image below is from a K-12M version

Image

You can see the RC portion (620 ohm + 0.1uF) of the C-RC snubber in the photo.
The C portion (0.01uF) is through the same PCB holes but on the opposite side (not shown).

Cheers


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PostPosted: 16 Oct 2010, 17:17 
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I did a similar modification with mine. But the snubbers on the bottom. That works too.

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PostPosted: 16 Oct 2010, 19:13 
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One of my points of confusion is that it appears to me that Voltsecond and Bruce appear to mount the tandem of the 620 ohm resistor and capacitor is two different places on the board. Is it because of different versions of the PCB?

I hope Voltsecond doesn't mind that I use his pictures below.


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PostPosted: 17 Oct 2010, 11:31 
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The voltsecond photos you have posted above do not show the C-RC snubber. What you see in those photos are only the four filament snubber capacitors - 1 uF Z5U 50V axial caps. There are no photos of the C-RC snubber on the voltsecond pages.
Cheers

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PostPosted: 17 Oct 2010, 16:12 
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Seeing these photos again makes me realize why point-to-point was less painful for my brain...trying to incorporate the mods from Bruce and VoltSecond while repeatedly flipping the PCB over...it just got too confusing!

In practice, I started by creating turret boards from schematics, but then realized these are useful only for the power supply section. The rest can be P2P.

Chuck-I found the layout software helpful in separating the various elements of the whole...namely, the power supply section from the amp section. PCB's make building quick but they don't provide much of an education about circuits. Plus, as we've seen, they definitely don't encourage modifications. For me, the real benefit comes from laying out circuits using either the actual components or with the layout software. And, as Bruce suggested in his article on circuit building, buying extra components makes a big difference when you realize there may be a more elegant way of attaching things when building commences.

Even using the layout software, I still find that my best results come during the actual building. The reason, I believe, is the actual building happens in three dimensions while the layout only offers two.

Keep on keeping on!
Lofton


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PostPosted: 17 Oct 2010, 22:52 
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Gio -

thank you for clarifying that.

Lofton - I have been reading circuits and looking at photos posted of point to point builds. I agree, with ptp you can get a better idea of what component is doing what.

-- Chuck


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PostPosted: 27 Oct 2010, 20:34 
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Another newbie starting to build this kit. I've built a few headphone amps in the past and decided to make the transition to a stereo amp. I've done extensive reading and have pretty well figured out what mods I wanted to do to this kit, one of which is adding the snubber caps to the tubes.

Being in Canada it can be hard to source quality parts inexpensively... is it worth spending the money on high grade caps here, or is what I can find at the local radio shack etc good enough? Also is there a consensus on what uf value caps to use... I've seen everything from 0.47uf to 1.0uf... what's best here? If people could list the part numbers of ones they've used successfully that would be a huge help, most of the mod pages I've seen list this mod, but not the part number.


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PostPosted: 30 Oct 2010, 13:08 
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Hi DisasterArea, welcome to the forum.

What part of Canada are you in? The Source (formerly Radio Shack) does not really have any suitable film capacitors. If you are using the DC blocking input caps, you may want to use a better brand here. Orange drops or solen are an inexpensive upgrade ($1-$2) inline with the low cost of the kit and an improvement over the stock capacitors.
Cheers

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