Buffalo GS20xx - Bypass 12V stage via 3 external PSs

[RickyV]

This is the BS-gs2016.

 

 

with temporary smps input.

[RickyV]

8 minutes ago, tgb said:

Cool !

Does it sound better with the LDOVR ?

Yes, this config already removed some harshness but you have to know that my audio switch is the ER and that I go via planettech, fiber, planettech to buffalo to modem router. Now I have a lps that powers the router and the buffalo with 13V and the 3A ldovr goes to 12V. 
Experimentation is still ongoing but at the moment I am rebuilding my NUC server power supply.

In the novel thread I already posted some of what I did to my buffalo 🐃.
 

No animals where hurt during this modd. 😀

[RickyV]

So I Frankensteined this today and it works,😀.
 

 

So I had to fall back to a smps to deliver the power, lower right corner.

From 7.5V I dropped it to 3.6V, that heatsink gets 60 degrees C. From this 3.6V I fed a 1A 3.3V module and a 2A 1.5V module. I used 2A module because dissipated heat/ power. 
The 1V, 5A was still a problem I started out with 4V on the input but that the regulators got about 80 degrees C, too hot. Than I tried it one diode, dropping 0.8V that dropped the temperature to 60 degrees C, still to hot. Than two diodes dropping 1.6V so now the 1V/5A regulator has 2V on its input and is about 50 degrees C now.

The heatsink’s from the first regulator and the diodes get about 60 degrees C. Even the smps get 43 degrees C.

So now that everything is working I will put it, temporary, in my system upstream of my Etherregen, connected by fiber.

So now I have to figure out what I need for a power supply. 
7.5Vx 5A= 37.5W    37.5W/3.6V= 10.4A at 3.6V ???

 

 

[RickyV]

15 minutes ago, tgb said:

Well done Ricky !

 

Regarding the amps, do you have a wattmeter or something to know how much the power SMPS deliver ?

the best is to use an amperemeter to check the amps at each voltage. It is on my todo list, this week.

7.5V/5A it is its max output ? not what it really deliver ?

Then, as your way to deliver the power is a chain 3.3 > 1.5 > 1, we can't guess the amps at each voltage this way (I think).

 

When I power it, I'll use a 4ports USB charger, 1 port per voltage, and will use a amperemeter to check the amps at each voltage. I'll do it quickly because last time the buck converter on the 1V got hot quickly (like you).

Apparently we face high currents (not too high anyway), thus, the final setup I see is : custom transformer (MPaudio can do that ; 4-6weeks delay ; around 70eur).

A "custom" transfo to get a tight dV at the regs (1V should be efficient vs regulation & not too big to keep the heat at minimum).

For instance / the 1VDC : I'll need 1+1=2VDC upstream the regs => with 2*0.4V=0.8V voltage drop in the diode bridge & the ratio 1.41 => (2VDC + 0.8) / 1.41 = 1.985VAC. So a rough 2VAC transfo output would be ok to get the 1VDC with a tight dV=1V at regs.

Hope this rough calculation is ok.

I think using a custom transfo is the only way to manage thoses V & A, and avoid at max the issues regarding the heat transfer at regs due to too high voltage drop.

 

You plugs the GRD of each voltage to the caps next to screws ? Interesting. Equipolarity by doing so ? I'll use your method, thanks.

Rgds

I have a multi meter but I haven’t measured the current. 
All the voltages have there one regulator and the 3 regulators get power from the regulator, top left corner, and that regulator gets power from the smps.

 

I am not sure if you can get a 2Vac transformer.

[RickyV]

21 minutes ago, Soul Analogue said:

Ok guys

 

today i found out why i could not power the gs2016a with my variable lab psu.... i tried to load test it.. and it could only supply stable volt at 1.6a at 1v.... 

so i have built my own 1v discrete regulator (i dont like monolitic regulators🙄sorry) and now successfully power it 

and i managed to measure the currents levels of these rails. Power up with two copper ethernet connections, max current Results as follows:

1v 2.5a

1.5v 0.2a

3.3. 0.7a

6 hours of work, problem solving and measurements....hope these figures help

Thanks that helps a lot. 
I think for the 1V we need a regulator that can dissipate a lot of heat so my 5A ldovr stack my not be the best solution in this spot. I also Have a couple of 5A newclassd regulators on hand that need a 5v voltage drop so then I can supply all regulators with 6v. The only problem with the newclassd regulator is that it’s minimal voltage is 1.8V so I still need a diode after it dropping 0.8 v.

 

oh and btw I had a listen last night with the buffalo in place and sounds really good.

[RickyV]

6 minutes ago, Soul Analogue said:

Oops.. tested again with power cycle:

the 1v max out at 3.1a ... not able to add sfp+ connections yet... the current drawn maybe higher...

And I think when it’s boots up there are much higher current peaks.

[RickyV]

17 hours ago, tims said:

Hi Ricky

Could you please give more details about the stacked modules you are using to get the 1.5v and 1v supplies?

Are they 1 amp LDOVR modules? I don't get how you actually stacked them like that.

Here is how to do that. You have to connect all the inputs and all the outputs of all the modules. Plus the set points of all the modules, last picture red arrow. 

 

You also have to put a drop of tin on the ENable pads where it says on off.

 

 

[RickyV]

11 minutes ago, Soul Analogue said:

using diode in series at the output of regulation should not be an ideal method... the diode can have different forward voltages at different current levels... making the voltage at the load not stable.... 

 

Thanks that is bad news that 1V is a real pain in the butt.

[RickyV]

On 8/1/2020 at 11:08 AM, tgb said:

Hi,

sorry i'm lazy to translate rigth now, please use Google Translate, please find there the last mod => http://forum-hifi.fr/thread-16891-post-382981.html#pid382981 (this post and the next ones).

Just ask if you need more info, right here.

 

To make it short :

I'm not expert, thus impossible for me to feed 1VDC at 4A minimum. So, the 1VDC is fed thru the input connector with 5VDC. As the 2 selfs on 3.3 & 1.5VDC are out => all the current goes to the 1VDC circuit.

As I wrote 1hours ago or so on the forum-hifi :

current on 3.3VDC is quite high : moving from 0.7 to 1.5A. I even lost the Buff htis night so I thnik it needed a pick above the 2A that the PS can deliver. Thus a 2.5A PS for the 3.3V seems to be a mnimum.

All tests are done with only 2 ports in use : 1 SFP (to other switch) & 1 RJ45 (to the streamer).

 

Interesting stuff. Final setup is not the one I expected but the high current at 1VDC is not for nood in electronics like me 🙂

 

@Tims :

powering the Buff with 5VDC instead of 12VDC should work, no problem. The issue is simply the amps : let's say thatyou need a PS able to deliver 3A minimum at 5VDC ; at 2A the PS will be close to its maximum output at steady state, so not secure.

Exact, as you say & as I learn yeateday on the forum-hifi from patatras : powering with 5VDC instead of 12VDC leads to better SQ.

Rgds

I have the 3.3v  running from a 1A lt3045 without it getting hot.

[RickyV]

On 9/1/2020 at 6:05 AM, tgb said:

Thus, as current is limited to 2.3-2.5A, I will upgrade the 1VDC with another MPAudio PS (ALS-HPULN), combined with a custom transfo 2.1VAC.

 

Not a big deal to fullfil the job on the 1VDC & pay more than expected, cause the mod on the 3.3 & 1.5 changes completely the Buff... very surprising...

 

Hi @tgb how is your 1V MP-audio and transformer comming along?

[RickyV]

1 hour ago, Soul Analogue said:

Finally I have tamed this freaking tricky bastard with full linear psu and regulators to a smooth power on and working state

pictures worth more than a thousand words

wow Soul it has become an elaborate switch.

[RickyV]

On 11/28/2020 at 11:16 AM, Soul Analogue said:

Finally I have tamed this freaking tricky bastard with full linear psu and regulators to a smooth power on and working state

pictures worth more than a thousand words

Hi soul, what clock are you using and on what voltage is it? Is it possible to use a crystek cchd-575?

[RickyV]

This is my Buffalo build. The challenge was to have one input voltage, keep the heat away from the LT 3045’s and to spread the heat between the power supply and the extra heat sinks in the buffalo. LT3045’s doesn’t do heat very well, with the 1V regulator being leading. Anything other then 1.8V leads too much heat in 5A regulator stack, it’s now approx 40 degrees. So I put a 5A regulator in front of each lt3045 to take the voltage drop/ heat.

 

 

[RickyV]

The power supply consists of a 10V, 80VA transformer, a 10000uF/40v Mundorf ag and a newclassd 5A regulator. 
At first I had the transformer on one secondary winding so 4A but the transformer got too hot for my liking/ continues use. With the full 80VA it is 37 degrees C with one sec it was more like 50 degrees C.