Power Supply Conversion – Converting a DPS800 Server PSU into a Standalone 12V PSU

conversionpower supply

I recently got my hands on 2 server PSUs from a HP Proliant DL380-G5.
HP model DPS-800GB A REV 06M Series HSTNS-PD05
Partno: 379123-001
(They appear to be made by Delta, going from the logo on the internal PCB.)

These can output a whopping 82A max at 12V (with 240V input), which would be very nice to power some LIPO battery chargers.

I know it is possible with the closely related DPS-700 and DPS-750 PSUs that use a very similar internal PCB.

Does anyone know how to convert/modify these DPS-800 units to function as standalone 12V power-supplies ?

Best Answer

Your PSU seems to be a common one and the necessary pins were determined by members of an external forum devoted to radio control enthusiasts found here. The solution seems to have been discovered by trial and error, and the poster claims that shorting pins 31 and 34 (which should be labelled) allows 12V to flow to the rail.

Server power supplies don't tend to have typical connectors like PC power supplies do, but instead have some sort of interconnect system consisting of pins or exposed pads like those seen below (with the resistor and solder omitted, naturally.

Most of the interconnect is taken up by those two large pads on the right which can generally assumed to be 12V and Ground given that the job of PSUs is generally to deliver 12V to the server rack at high current. That doesn't leave many pins left to test and process of elimination can narrow the choice of which pins you should test.

One member of an RC forum compiled a short guide on determining which pins to short if you're going in blind given some assumptions about how the supply works and what it expects. Since these PSUs usually short the DC ground to the chassis ground, all of the ground pins can be determined using a DMM and eliminated. From there, the voltage on the rest of the pins can be referenced to ground and the number of pins to test is decreased substantially. Shorting one or more of those pins to ground through a resistor should likely result in the PSU turning on.

Note that this assumes that the power supply in question requires a simple active-low/high logic voltage to turn on. More complicated supplies or supplies requiring some other control signal will likely not work in this fashion.

Related Solutions

Type bit does not match with the integer literal while converting integer into bit_vector

To answer your specific question: the to_bitvector() function from std_logic_1164 only takes one input, a signal of type std_ulogic_vector or std_logic_vector. If you search for the function name you find documentation like this which gives the interface

function to_bitvector ( s : std_ulogic_vector ) return bit_vector;

So change your code to this and it should work (though I haven't tested):

for i in 0 to 5 loop
    x_std(i) <= conv_std_logic_vector(x_int(i),14);
    x_bit(i) <= to_bitvector(x_std(i));  --should compile
end loop;

As to why the functions take different inputs, the conv_std_logic_vector function requires a length parameter as the integer type has no specific length. The length parameter tells the synthesiser how wide a std_logic_vector is created by the function. VHDL is strongly typed and the length of the signal returned from the function is then checked against the left hand sign on the assignment (x_std(i)) to ensure they match.

Conversely, the to_bitvector function simply goes through each element of the array in turn performing a mapping from std_logic to bit and the returned array width is therefore defined by the width of the input array.

It's also worth looking into using VHDL attributes as the length input to conversion functions. This code won't break if you decide to change the width of x_std() and x_bit() later:

x_std(i) <= conv_std_logic_vector(x_int(i),x_std(i)'LENGTH);

PC psu 12v and 5v connection in parallel

Current will flow from the 12v to the 5v volt rail, causing a short and the PSU to shut down.

You know that if you short out i.e. 5v and ground then high current will flow and the power supply turns off to a) don't overheat and b) don't burn you wires (or something along those lines). Voltage is relative, so 5v - 0v = 5v difference; 12v - 5v = 7v, that's the same as shorting 7v and ground.

Best Answer

Related Solutions

Type bit does not match with the integer literal while converting integer into bit_vector

PC psu 12v and 5v connection in parallel

Related Topic