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KGSSHV Carbon Build Thread


mwl168

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Chassis are semi-customized and buttons are also from the manufacturer. Separated PSU theoretically would prevent 60HZ AC noise. The reason I use separated box was much simpler.... Because it's hard to fit GG in one box or it would be HUGE. Since customized chassis has MOQ, I want carbon, GG, BH to share a same design to lower the cost of customized chassis.  I had to order a batch of those. So yeah, more amps coming.

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DSC_6703.jpg

Edited by joehpj
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18 hours ago, Whitigir said:

Awesome build! What chassis, and where do u get the power button from :D ? Is there any real advantage to go with Separated PSU box ? I am planing to build with Dissipante, but mini-dissipante may works better ?

It looks like a Bulgin Vandal resistant switch, something like this http://www.bulgin.com/products/switches/push-button/stainless-steel-push-button-mp0045-1d0-mp0045-3d0-mp0045-1e0-mp0045-3e0-series-18mm-diameter-group.html (possibly the illuminated version).  Mouser has a bunch of different versions..

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On 04/03/2017 at 2:28 AM, Whitigir said:

My GRHV has 

 
511-STN9360
 
On the back
so it will need 2x.  While the BOM list doesn't have it yet.  The whole things need 6x as 2x are on each channel board
 

The opening post lists it in the BOM. It also lists it in the Mouser project cart. :rolleyes:

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2 hours ago, Whitigir said:

Hm, low voltage is working.  However the amp board has very weak LED and test point doesn't measure to anything.  Anyone has any idea ?

You need all the voltages to work before doing any further trouble shooting

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12 hours ago, Whitigir said:

I thought I only need Low voltage to be able to adjust the current, offset, and balances trims ?

You can trim the CSS's using only LV and a DMM in mA mode (assuming AMP board is not connected to anything):

Connect LV+ -> AMP HV+
Connect LV- -> DMM (Common)
Connect DMM.(+) -> the probe
put the probe to the tail of the CSS (the Drain of the Sics (middle leg))
Now you'll have the CSS current reading directly on the meter, and the CSS can be trimmed to what ever current < 27mA you have sinks for
(one might shoot a mA lower as the current grows a bit at higher voltage and heat).

Trimming the output stage tail resistor to get the amp in balance and DC balance requires all voltages

 

 

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The cascode current source can be set with an LV source.

Connect positive voltage to B+ terminal of the amp board. Connect negative voltage to the end of the 100ohm resistor adjacent to the DN2540 away from the heatsink. Measure voltage between the testpoints. Adjust until measurement is 1V for 20mA. (Calculation is 50ohms / 0.02A = 1V).

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Thank you so much to 

4 hours ago, insanity said:

The cascode current source can be set with an LV source.

Connect positive voltage to B+ terminal of the amp board. Connect negative voltage to the end of the 100ohm resistor adjacent to the DN2540 away from the heatsink. Measure voltage between the testpoints. Adjust until measurement is 1V for 20mA. (Calculation is 50ohms / 0.02A = 1V).

I have successfully adjusted the current using your method.

I have made out a picture here for future people needs

 

https://imageshack.com/i/plNJXzaHj

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