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KGSSHV Carbon Build Thread


mwl168

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Would you not mount the amplifier PCB with the transistors at the bottom of the heatsink? In that case, the balance pot is at the top and the standard straight pot should be OK to adjust even after the board is mounted?

 

//UFN

That's a good idea, I actually have not thought of. I think that is possible and is probably the best solution to prevent everything from getting too cramped. 

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On the BOM Edit 9/18 on line 19, the cap 80-C320C104J5R is shown as 0.1uF 50V

On the PCB it is 1Uf 50V

Out of town at the moment so cannot check the board. But I believe these caps  (80-C320C104J5R) are for the servo. There is another 1uf cap (ECQ-E2105KF) listed in the BOM for the 1uF position. Will double check when I return home.

Edited by mwl168
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Noticed the LED in Carbon v5 BOM is 1.7V. Not sure but I think the designer has 2.1V in mind.

https://docs.google.com/spreadsheets/d/1tQvwqsARXGge6Tw6edqicCDti6Mite2F24T5YddyEEc/edit#gid=0

Lil Knight's BOM(KGSSHV) were already 1.7V LEDs.

Should we use 1.7V or 2.1V for Carbon will be correct?

Edited by palchiu
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I purposely picked the 1.7V LED because that's what I built the KGSSHV with.

If you read the original KGSS article Kevin published in HeadWize, the first and second stage LEDs will even each out regardless of 1.7V or 2.1V LED used. However, higher voltage LED on the output stage will bias the amp to run at higher current I believe.

Hope Kevin, Burger or others can chime in. 

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On the BOM Edit 9/18 on line 19, the cap 80-C320C104J5R is shown as 0.1uF 50V

On the PCB it is 1Uf 50V

Checked the board today. 80-C320C104J5R (two needed) is for the servo position. 667-ECQ-E2105FK (one needed) on the BOM is for the 1uF/50V position on the board. It's 1.5mm lead spacing and rated 250V. 

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Yeah, sorry for that,

 

That's what I get for doing things like this at 3AM in the morning.

 

I completely missed those 2 caps in the servo.

I should have twigged to the fact that the lead spacing was all wrong.   My bad.

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No worries. 

Please do continue to report errors in the BOM and suggest more appropriate or better parts to use. Especially those capacitors, the size and lead spacing can be tricky and I am never quite sure what material of capacitor to use for some of the positions.

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Please check the 5pf cap, the one I received was way too large.  I am not sure if this has already been corrected?  This P/N works: 75-561R10TCCV50

Thanks

 

If you are talking about the GR HV Dual BOM, the P/N you listed is what's currently in the BOM. I do remember I first started the BOM using mica caps and later changed it.  Sorry about that.

The mica caps are larger in size and more expensive and I don't know if it offers meaningful advantage in this particular application. 

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We ordered from the BOMs that were first posted. Everything was good except the 4700uf caps for the 15v PS need to be 16mm dia with 7.5mm lead spacing.

Also as mentioned above, to get to 20ma (1v across the testpoints) you will need to lower the 182 ohm resistor by the offset pot to 120 ohm. 

Amp been running for 3 hours without any issues. Initial impressions? Reminds me of the T2!

Many thanks to Kevin, Brigir, Michael and others for an outstanding design and for putting this group buy together.

Photo is from yesterday before installing the transformer and the wiring.

Carbon Left Side.jpg

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Amp been running for 3 hours without any issues. Initial impressions? Reminds me of the T2!

There is a reason KG and I are selling off our T2 parts...  :)

Is a change to 100ohms also acceptable since I didn't order 120ohm resistors? Has this change anything to do with variance in parts of the ccs?

You could even go lower than 100R so no problem there. 

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