Young Year YP-AB Transparent Power Supply
By Gabriel Torres on January 15, 2007


Young Year YP-AB, which is also sold under several other brands (Aspire/Apevia, Levicom and Leadership), is an aluminum power supply with a big transparent acrylic cover, so you can see inside the power supply, being a very interesting choice for users that like transparent cases or cases with a transparent side window. Available in models ranging from 350 W to 520 W, in this article we fully disassembled this unit and discovered that internally it is a trashy “generic” power supply. Read on.

This power supply is actually manufactured by a Chinese company called Sun Pro.

The external looks of this power supply really caught our attention (see Figures 2, 3 and 4) and that is why we decided to buy in order to take a better look. After removing it from its box, you need to peel off the transparent film that protects the unit, like shown in Figure 1.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 1: Removing the transparent protective film that comes with this unit.

This power supply uses two 80 mm fans, one at its rear and the other on its front, as you can see on the pictures below.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 2: Young Year YP-AB Power Supply.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 3: Young Year YP-AB Power Supply.

Introduction (Cont’d)

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 4: Young Year YP-AB Power Supply.

It is impossible to not have an opinion about the aesthetics of this power supply: you will either love it or hate it. In our case, we liked its transparent cover, however we found the color choice for the plastic parts too cheesy – we think this power supply would be more beautiful if all its plastic parts were also transparent. Of course this is a matter of personal taste. All plastic parts were made lime yellow in order to glow under UV light. The power supply heatsinks and the main electrolytic capacitors (from the voltage doubler) also glow under UV light.

This power supply has only three peripheral power cables: one Serial ATA power cable containing only one SATA power connector and two peripheral power cables containing three standard peripheral power connectors and one floppy disk drive power connector each. The main motherboard cable has a 20-pin connector, with a 4-pin extension in order to transform it into a 24-pin connector. No auxiliary PCI Express connector is provided.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 5: Power supply cables. The plastic parts are UV-sensitive.

All wires are 20 AWG, which are too thin for today’s requirements.

This power supply has a potentiometer to manually control the speed of its fans, as you can see in Figure 6.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 6: Fan speed control.

As you can also see in Figure 6, this power supply has a 110/220 V switch, meaning that it doesn’t feature active PFC.

As already mentioned, this power supply housing is made of aluminum (blue on the model we bought).

We decided to fully disassemble this power supply to take a look inside.

A Look Inside The Young Year YP-AB

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works inside and to compare this power supply to others.

In this page, we will have an overall look, while in the next page we will discuss in details the quality and rating of the components used.

On Figures 7 and 8 you can have an overall look from inside this power supply.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 7: Inside Young Year YP-AB.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 8: Inside Young Year YP-AB.

What immediately caught our eye was the marking “Model ATX-66B.” We found out after a quick search on the net that this is the exact same PCB used by other power supplies manufactured by Sun Pro, including some models they OEM to Young Year, Ultra (X-Connect 500 W) and Aspire/Apevia.

Transient Filtering Stage

As we mentioned on other articles, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components than that, usually removing the MOV, which is essential for cutting spikes coming from the power grid, and the first coil.

This power supply filtering stage isn’t good at all. It features only one ferrite coil (instead of two) and two Y capacitors. There is a ceramic disc capacitor labeled as “J101” but this capacitor is connected in series with the main AC power line instead of in parallel. So this power supply missed one MOV, one ferrite coil and one X capacitor just to have the basic recommended components for this stage. It is interesting to notice, though, that there is empty space for installing the X capacitor (labeled “CX102”) and the second ferrite coil (labeled “LF103”). So, some models using this same PCB may have a more complete filtering stage (which is the case of Ultra X-Connect 500 W and the model sold in Europe by Levicom) – but still missing the MOV. The European version also features passive PFC.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 9: Transient filtering stage.

We found something really bad on the model we disassembled: it hadn’t a NTC thermistor. As you can see in Figure 10, it had, instead, a wire jumper on its place (labeled “TH101”).

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 10: The thermistor is missing on this power supply!

In the next page we will have a more detailed discussion about the components used in the Young Year YP-AB.

Primary Analysis

This power supply uses one KBL406 rectifying bridge in its primary, which can deliver up to 4 A (rated at 50° C). No heatsink was used to cool down this component. This is the most low-end rectifier we’ve seen on a power supply to date. With this 4 A limit the power supply would only be able to pull up to 460 W from the power grid at 115 V. Assuming a typical efficiency of 80%, this means that this unit would be able to deliver only up to 368 W on its outputs without burning this component. And this unit was labeled as a "550 W" model! Of couse to truly test this power supply we would need a load tester, equipment that we still don't have.

On the switching section two 2SC2625 NPN power transistors are used using the half-bridge configuration, which is the most common configuration for power supplies without active PFC. Each transistor has a maximum rated current of 10 A @ 25° C (or 20 A peak current). Of course maximum current at real-world temperatures will be lower.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 11: Two power NPN transistors are used on the switching section.

Secondary Analysis

This power supply uses three power Schottky rectifiers on its secondary section, one for each positive output: +3.3 V, +5 V and +12 V. The only advantage of this power supply compared to 100% “generic” units is that on this unit the +3.3 V output has a separated rectifier – sharing, however, the same transformer output as the +5 V output. In old ATX power supplies, a voltage regulator connected to the +5 V output provided the +3.3 V output.

Since this power supply is based on the half-bridge configuration, to calculate the maximum theoretical current is easy: all we need to do is add the maximum currents from the diodes.

The +12 V output uses one STPR1020CT Schottky rectifier, which supports up to 10 A (at 110° C, 5 A per internal diode). So the +12 V output has a maximum theoretical power of 120 W, an outrageous discrepancy from what is printed on the power supply label (we will talk more about this in the next page). The maximum current this line can really deliver will depend on other components, especially the transformer, the coil, the wire gauge and even the width of the printed circuit board traces used.

The +5 V output uses one SBL3040PT Schottky rectifier, which supports up to 30 A (at 95° C, 15 A per internal diode). So the +5 V output has a maximum theoretical power of 150 W, another discrepancy from what is written on the power supply label that we will talk about in the next page.

The +3.3 V output also uses one SBL3040PT Schottky rectifier (30 A at 95° C, 15 A per internal diode), so the +3.3 V output has a maximum theoretical power of 99 W, another discrepancy we will talk about in the next page.

Even though the +5 V line and the +3.3 V line have separated rectifiers, they share the same transformer output. So the maximum current both lines can deliver will depend a lot on the transformer.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 12: Power rectifiers used on the secondary.

In Figure 13, you can see a thermal sensor touching the secondary heatsink, which controls the fan speed.

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 13: Secondary thermal sensor.

Power Distribution

The joke about this power supply starts on the website from the original manufacturer. As you can see there, all their models are deliberately overspec’ed. For example, the “KY-550ATX” model is a “450 W” model, believe it or not. The problem, however, is that on the website from the original manufacturer there isn't any power supply with the exact current specs as present on the label from this unit.

If you take the 500 W model sold by Apevia (ATX-AS500W-BL), you will see that it has the same label as the Young Year YP-600-AB model, which is labeled by Young Year as a 500 W unit. But on Apevia’s website there is one interesting thing. Two, as a matter of fact. The first one is that contrary to Young Year’s website all the currents are labeled as “maximum,” with lower specs labeled as “normal.” These “normal” currents would be 20 A for the +3.3 V output (instead of 28 A), 24 A for the +5 V output (instead of 30 A) and 25 A for the +12 V output (instead of 34 A). Even then we think these numbers aren’t real, as we shall discuss in more details in a moment. The second thing we notice was this funny typo, where “tolerance” was written “torrance.”

The model we bought was labeled by Brazilian distributor Leadership as a 550 W model, and the crazy thing about it is that is impossible to find any model at both the original manufacturer's (Sun Pro) and Young Year’s websites that has the same label as this unit. Even worse, as you can see in Figure 14, the label also lists the specs for two other models, 600 W and 700 W, that we also can’t find at any website (original manufacturer and "clone" manufacturers). So we think Sun Pro will simply print whatever you pay them to print. Do you want a 900 W power supply? No problem, we will make the sticker for you!

Young Year YP-AB Transparent Power Supply
click to enlarge
Figure 14: Power supply label.

As we saw in the previous page, the +3.3 V, +5 V and +12 V rectifiers used by this power supply can only deliver up to 30 A (99 W), 30 A (150 W) and 10 A (120 W), respectively. Keep in mind that these are the maximum currents and power specs for the rectifiers only, the maximum current/power the power supply is able to deliver will depend on the other components used, especially on the transformer, on the coils and even on the width of the printed circuit board traces.

The point is. NO YP-AB model can deliver what the manufacturer says. If you take the smallest model, YP-450-AB, which is officially a 350 W unit, its +12 V line is labeled as 15 A while the +12 V rectifier can only deliver 10 A!

The difference between the components used and the Leadership model we bought is outrageous, they labeled the +3.3 V, +5 V and +12 V outputs as capable of delivering 32 A, 34 A and 36 A, respectively, which is impossible using the components we found inside this unit. The most absurd difference is on the +12 V output (10 A/120 W vs. 36 A/432 W).

Some reader could point out that we are wrong as the maximum current of each rectifier is labeled under temperatures above 100° C and thus they could deliver a higher current when running at a lower temperature. This could make a little sense, however we’ve never seen a power supply where the rectifier maximum current is lower than the current printed on the label. Actually it is the contrary that normally happens: the rectifier maximum current is higher than the power supply labeled current – the double, in some cases.

The information that this is a 550 W (or any other power spec above 350 W) is a complete lie. Unfortunately we don’t have the required equipment to see the maximum power we could pull from this unit.

Just as an exercise, if we added up the maximum theoretical power for the three main positive voltages, we would have 369 W. Since +5 V and +3.3 V outputs are connected to the same transformer output, we cannot simply add these two powers, as one output limits the other. If we considered a combined power of 150 W (the maximum theoretical power for the +5 V output), we would have a maximum power of 270 W for the main positive voltages. Keep in mind that this is a theoretical value and the real value is usually lower.

Another detail is that this unit has a -5 V output, which is present only on very old power supplies, as this output was removed from power supplies years ago.

Main Specifications

Young Year YP-AB power supply specs include:


This power supply is a bad Chinese joke. Outside it is beautiful, but inside it is nothing but a very low-end generic unit.

Its main problem is that it cannot deliver its labeled 550 W – in fact, not even the 350 W model can deliver its labeled power. We don’t have the proper equipment to find out how much power this unit can deliver, but based on its internal architecture, on the components used and on our experience, we speculate that this is really a 150 W power supply.

It is a pity, because the idea of a transparent power supply is really interesting. But if you are a serious case modder, how about buying a decent power supply and creating a transparent acrylic cover for it by yourself? After all, isn’t the whole idea of case modding doing things by ourselves to impress our friends?

Originally at

© 2004-15 Clube do Hardware, all Rights Reserved.

Total or partial reproduction of the contents of this site, as well as that of the texts available for downloading, be this in the electronic media, in print, or any other form of distribution, is expressly forbidden. Those who do not comply with these copyright laws will be indicted and punished according to the International Copyrights Law.

We do not take responsibility for material damage of any kind caused by the use of information contained in Hardware Secrets.