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

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.

Edited May 2, 20179 yr by joehpj

Love the modular concept that leverages the PS across several amplification platforms.  Smart and efficient IMO.

HS

18 hours ago, Whitigir said:

Awesome build! What chassis, and where do u get the power button from  ? 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..

Hello, 

i have a noob question and I need some helps please.  I am seeing 1M resistor on the Boards, and there is no resistor of this value on the BOM in the first post ?  Also, can someone please confirm to me that the middle resistor of 1.5k here is to be 750 ohm instead ? Thanks

the pair of 1.5k resistors and the 10 volt reference make a 20V output voltage

the pair of 1M resistors and the 100k pot are for trimming the output voltage and are optional

not sure where the 750 ohm came from

 

 

2 minutes ago, kevin gilmore said:

not sure where the 750 ohm came from

15V

That is awesome, so I can directly connecting the Pot without the miniboard ! Thanks for confirming

Just now, Whitigir said:

That is awesome, so I can directly connecting the Pot without the miniboard ! Thanks for confirming

might be stretching it a bit  ... the two 1Meg + trim is really only needed if you care about mV accuracy ...you can omit those

for 15V, have to recalculate the values of the 1M resistors. So one of them would need to be 473k

 

 

Edited February 28, 20179 yr by kevin gilmore

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

 

 

 

 

I have another noob question .... how do we de-energize the bias properly ? Do we drain it at the "bias TP" similar to draining a capacitor ?

I usually do it before the 10m90s current source.

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. 

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 ?

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

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

No.  You'll need all as Soren said.

Great! Thank you for the confirmations ! It is horrible to be lacking only 1 thermal alloy and it washer to complete the HV lol!

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

 

 

13 hours ago, Whitigir said:

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

umm, you might want to rethink doing this...

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).

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

So I fired it up, everything works, but one of my amp board is not working as only 1 led is on, the second led on the HV is not on :(.  Anyone has any clues ? I think I smell something and...50k resistor is burned out

Both PZTA 56 is also not working >_<