Internal components
Starting with the fan, Ultra has chosen to cool the unit with a 135mm Young Lin fan that spins at 1700RPM for a total airflow 91.16CFM. Because of the geometry of the fan’s mount, however, the CFM won’t be quite as high as its rating. Nevertheless, Ultra’s chosen fan is more than sufficient to cool a power supply of this output.
Primary side
In power supply parlance, the “primary side” of a PSU refers to all the electronics in the chain prior to the transformer. You can identify the primary side as the one with one or more large capacitors. As you can see in the image below, the ULT-HA750X uses a single 470µF/450V Nichicon LN-series capacitor, which is of good quality, but not the best. The presence of a single capacitor also indicates that this unit features PFC.
The first stage of the PSU’s primary side is designed to filter incoming AC power from the wall of its transients (spikes in current) and of any noise (erratic/random current). This is called transient filtering. Doing this ensures that power heading into the unit for transformation into DC is clean, and that the electronics of the PSU don’t send noise back into the mains to cause interference with other electronic devices.
A “standard” breakdown of the parts included in the transient filtering stage of a PSU is a metal oxide varistor (MOV), two ferrite coils, two Y capacitors and one X capacitor. These can be placed in a “row” so to speak, or broken into two parts, with one section of the transient filter near the plug, and the remainder connected directly to the unit’s PCB. In this case, the ULT-HA750X follows the latter model.
Starting at the plug, we see an X capacitor in yellow, and a parallel pair of Y capacitors soldered directly to the line in. This is not a bad design, per se, but it would be better if these components were attached to a small PCB. Moving over to the second stage, we find an MOV, two coils, two Y capacitors and two more X capacitors. In all, the ULT-HA750X offers more than the standard set of components, meaning everything is excellent on this front.
Filtering, first stage: (1) X capacitor, (2) Y capacitor, (3) Y capacitor.
Filtering, second stage: (1) MOV, (2) coil, (3) Y capacitor, (4) Y capacitor, (5) X capacitor, (6) coil, (7) X capacitor.
The second stage of the primary side is designed to convert the ~120V/60Hz AC current from the wall to a DC current, where it will be ready for manipulation by a later stage of the power supply’s primary.
Moving to look at the rectification bridge on the primary side, the ULT-HA750X comes equipped with a GBJ1506 (PDF) bridge rectifier. The bridge rectifier is responsible for creating a DC current out of what has just been taken from the wall and filtered.
The spec sheet tells us that this unit can handle 15A at 100C with a heatsink, which this bridge rectifier has. With a minimum efficiency rating of 82%, this stage of the supply can handle a delightfully overspec’d 1476W. The real capacity of the PSU is, of course, the product of other components along the line, but it’s good to see a manufacturer picking parts that do not cut a close margin.
Rectification stage: (1) GBJ1506 bridge rectifier.
The third stage of a power supply primary equipped with PFC is the PFC circuit. Power factor correction is designed to reduce reactive power, a sort of “dissonance” on the mains that creates heat, which utility companies must address with more expensive power lines and equipment.
One way to think of reactive power is a “push wave” that moves a “flow wave” of electrons from point A to point B, where the electrons go on to power your device. Usually the push wave and the flow wave work in harmony, making the entire power grid happy and efficient.
Some devices, however, like power supplies, muck everything up by throwing the push and the flow out of sync. This makes usable energy, which we have called the flow wave, harder for a device to use. When the flow wave weakens, reactive power steps up with a stronger push to keep those electrons flowing to your device at a nominal level. If the power grid cannot push the flow at a sufficient level for the grid’s thousands of connected devices, then the grid “sheds load” by cutting power, which may have been responsible for more than one blackout in your neighborhood. If the grid didn’t shed load, however, every device in your home or neighborhood could have easily browned out and died.
More catastrophically, a high degree of reactive power heats up the transmission lines you see on utility poles. We know this because more electricity plainly equals more heat. Heated wires get very malleable and begin to sag, at which point they can touch trees and the like, which forces the power grid to shut those wires down. The remaining active wires in a grid must now bear this load, and if there is insufficient capacity to do so, a cascading blackout can begin. If you remember the great northeastern blackout of 2003, an excess of reactive power was a leading catalyst.
When we speak of “power factor,” then, we refer to a number which describes the amount of power available on the flow wave as a percentage of the total effort expended by the grid to power a device. Power supplies without active PFC have an abysmal power factor of about .6, which means only 60% of the total power consumed is usable energy. Power supplies with active power factor correction, such as this 750W Ultra model, kick that power factor up to .9 or higher. Imagine how much more efficient our energy grid could be if every PC had a great power supply with PFC? Alas, the world is filled with cheap OEM power supplies that forgo the circuitry to cut costs.
Power factor correction for the ULT-HA750X is performed by a pair of Infineon SPW21N50C3 (PDF) power MOSFET transistors. As an interesting note, these same components are used on the X4 850W model, meaning that Ultra has overspec’d for the PFC as well. Note also that the large coil and the capacitor are used at this stage to complete the PFC circuit.
PFC stage: (1) Capacitor, (2) SPW21N50C3 MOSFETs, (3) Coil.
The final stage of a typical power supply’s primary is designed to convert the DC power sent by the rectification stage into a very high frequency alternating current.
While it seems absurd to convert DC power back into AC, there is a reason: the size of the transformers in a PSU is inversely proportional to the frequency of the current, meaning that a very high frequency alternating current allows for transformers that actually fit in a power supply. The transformer is essential to a PSU, as they feed the secondary side of the power supply with a current it can use for output to your PC’s components.
Ultra has used a pair of SPW21N50C3 switching regulators arranged in the very common double forward configuration to perform this DC-to-AC conversion; these can found on the primary’s main heatsink. The function of these regulators, to conclude the primary, is controlled by the famous Champion Micro CM6800 PWM/PFC controller, which also manages the Ultra’s PFC circuitry.
(1) Main heatsink, (2) SPW21N50C3 switching regulators, (3) CM6800 PWM/PFC controller.
Now that the primary side of our power supply is done filtering and converting the power, it passes through the transformers and heads off to the secondary.
Done in yellow, the main (left) and secondary (right) transformers.
Secondary side
The role of the secondary side of the power supply is to convert the high-frequency alternating current coming out of the power supply’s primary side into a smooth, even DC that can be used by your system’s many parts. The Ultra 750W unit depends on several components to regulate this stage, and all of them can be found on the heatsink.
Starting first with the system’s +12V output, Ultra has chosen four ESAD83-004 Schottky barrier diodes (PDF) to do the job. Assuming a duty cycle of around 30%, the +12V has capacity for up to 85A/1020W, which is more than sufficient for this power supply. Keep in mind, however, that this sort of capacity is theoretical–actual PSU performance ultimately depends on other components, particularly the coils on the PSU’s secondary.
Moving on to the +5V and the +3.3V, each are overseen by a pair of SPR30L30CT Schottky (PDF), offering up 43A/215W and 42A/141W of capacity, respectively.
Finally, the +5VSB is handled with a simple 20A STPS20L60CT Schottky, which is more than sufficient to keep your motherboard’s little standby LED and power switches working.
(1) Secondary heatsink, (2) ESAD83-004 Schottky, (3) SPR30L30CT Schottky, (4) STPS20L60CT Schottky. Unseen: Additional Schottky diodes on obverse.
Rounding out the Ultra’s secondary, we can see a trio of coils (one for each rail) and Teapo capacitors (acceptable quality) to perform final filtering, as well as a PS232 controller circuit, which provides this unit’s over current protection (OCP), under voltage protection (UVP) and over voltage protection (OVP).
(1) PS232 controller, (2) Teapo capacitor.
Though we have to ding the ULT-HA750X for some kludgy hand-soldered elements, the unit otherwise offers well-appointed circuitry. Both the primary and secondary sides have ample capacity to spare, which help to combat ripple (fluctuating current) and transients (current spikes) as the critical filtering and rectification stages are not already working close to their limits.
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