Computer psu and usb 5v rail issues

[russells55]

Hi hi.

I have a little project on the go. I took an old PC tower. Gutted pretty much everything but the PSU out (no mother board . Dvdrom etc)

I have a put in 2 grid blades for mining.
And so a pair of 2pac geeko science usb miners

The grid blades need 12 volt power. So i just cut into one of the many 12v supply lines one is off a molex other from a feed to the old Motherboard.
Im told they use about 75watts each
Then a raspberry pi3 controls it.  They work like a charm!

As for the usb miners. I have a pi 1 control them in the case too. They are both plugged into a usb powered hub.  At 175mhz there pulling 6-8watts (i have a meter to track it)   

However the voltage is terrible.

With NO load its 4.99v right at the usb miner stick , on but idle.

If i check other 5v feeds off the psu closer and before my grade 8 soildering skills i get 5.06v to 4.99v

That would all be ok but with one usb miner running. The voltage drops too 4.71v. With both 4.22v 
Then the sticks sooner or later crash (or atleast 1 will)

I have tried 2 usb other hubs.
Other 5volt feeds off the PSU
Still the huge voltage drop.

I also found a random power plug i think for a very old portable house phone rated 5volt 3A.  It test 5.08volt
I plugged that in the hub as the power And with both sticks running it drops to 4.89v at the stick.

This is a 480watt computer psu. Any idea why it cant handle powering a usb hub?


Russ

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[VasilyS]

You need to use a USB hub with external, separate mains power. This will remove the load from the computer's power supply.

[philipma1957]

Hi hi.

I have a little project on the go. I took an old PC tower. Gutted pretty much everything but the PSU out (no mother board . Dvdrom etc)

I have a put in 2 grid blades for mining.
And so a pair of 2pac geeko science usb miners

The grid blades need 12 volt power. So i just cut into one of the many 12v supply lines one is off a molex other from a feed to the old Motherboard.
Im told they use about 75watts each
Then a raspberry pi3 controls it.  They work like a charm!

As for the usb miners. I have a pi 1 control them in the case too. They are both plugged into a usb powered hub.  At 175mhz there pulling 6-8watts (i have a meter to track it)  

However the voltage is terrible.

With NO load its 4.99v right at the usb miner stick , on but idle.

If i check other 5v feeds off the psu closer and before my grade 8 soildering skills i get 5.06v to 4.99v

That would all be ok but with one usb miner running. The voltage drops too 4.71v. With both 4.22v  
Then the sticks sooner or later crash (or atleast 1 will)

I have tried 2 usb other hubs.
Other 5volt feeds off the PSU
Still the huge voltage drop.

I also found a random power plug i think for a very old portable house phone rated 5volt 3A.  It test 5.08volt
I plugged that in the hub as the power And with both sticks running it drops to 4.89v at the stick.

This is a 480watt computer psu. Any idea why it cant handle powering a usb hub?


Russ

most likely a garbage generic psu

here is a link to a quality 5 volt psu that has voltage control

https://www.trcelectronics.com/ecomm/pdf/lrs75.pdf

it will do 3 sticks and give 15 watts a stick

you could set to 5.5 volts which will sag to 5.1 or 5.2 as they all sag

sidehack has built a good  usb hub can do six sticks at 10-15 watts

I personally use this one

https://bitcointalk.org/index.php?topic=5053711.msg48725753#msg48725753

https://www.eyeboot.com/sipolar-10-port-usb-hub.html

[russells55]

The is Psu is a Actec neo480

https://www.newegg.com/Product/Product.aspx?Item=N82E16817103924

The 5v rail is rated for 38A  i and using what 5A. 

Could a dc to dc buck converter help here.

If i Bring the voltage to 5.2 or something.
I noticed on my good usb power adapters like the one that i have for the raspberry pi the voltage output is 5.19v
Or 5.16 on a phone charger i have.

Do you think supplying say 5.25volts to the hub is a good idea?

Cheers

[philipma1957]

The is Psu is a Actec neo480

https://www.newegg.com/Product/Product.aspx?Item=N82E16817103924

The 5v rail is rated for 38A  i and using what 5A. 

Could a dc to dc buck converter help here.

If i Bring the voltage to 5.2 or something.
I noticed on my good usb power adapters like the one that i have for the raspberry pi the voltage output is 5.19v
Or 5.16 on a phone charger i have.

Do you think supplying say 5.25volts to the hub is a good idea?

Cheers

if you add this it is 12 dollars

https://www.amazon.com/Converter-DROK-Regulator-Adjustable-Transformer/dp/B06XG2KPTS/ref=sr_1_3?

set to 5.3 or 5.35


or buy this

https://www.trcelectronics.com/mean-well-power-supply-lrs-75

https://www.trcelectronics.com/View/Mean-Well/LRS-75-5.shtml

it is 15 dollars 86% efficient

or buy the hub I used.

[DocDrydenn]

I'm glad to hear that I'm not the only one still running these USB ASICs.

I've currently got the following running on one of my rigs:

4x GekkoScience 2PAC
2x Gridseed Orb
1x Blizzard Zeus
1x Futurebit Moonlander 2
1x Nanofury NF1

1x GTX 1070
1x GTX 1060
1x RX 570
(Hell, I even mine cryptonight_heavy on the two Xeon X5670 CPU's in this rig.)

For the ASIC's, I went with two Plugable USB 2.0 7-Port Hub with 60W Power Adapter's I got on sale from Amazon. https://www.amazon.com/Plugable-7-Port-Speed-Charging-Adapter/dp/B00L2LK164/ref=sr_1_1?ie=UTF8&qid=1547123579&sr=8-1&keywords=B00L2LK164

I'm running all this (9 different hardware devices across 9 different software miners) on PiMP OS (a Linux-based mining OS).

[russells55]

What is your voltage on say the 2pac sticks when running.

Does the hub stay at say 5.1v always or anything like that?