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Old 07-01-2017, 05:48 PM   #2727
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Post Jeantech JNP-500AP (PCB No:380 REV:B5 2005-07-12)

It’s been a while since I posted anything in this thread.

Here is a Jeantech JNP-500AP power supply (PCB No:380 REV:B5 2005-07-12) that member Pentium 4 gave me a while back (thanks man!!)

As usual, we start with the outside shots:
It’s nothing special on the outside, though the case is made of decent sturdy metal. Output wires are all 18 AWG. And as you can see, this PSU has a cubic butt-ton of Molex connectors for whatever reason (at least they are good quality Molex, and not the cheap PSU kind). For connectors, this is what we get:
20+4 pin main connector, 4-pin 12V CPU connector, 9 Molex, 2 floppy, 2 SATA, and a fan monitor. NO PCI-E 16x, unfortunately! :\

Moving on to the label:
That label looks familiar. I cannot remember on which PSUs I’ve seen it exactly, but it looks like Sirtec. Indeed if you search for the UL number online, E144195, you will find that it is a Sirtech power supply. And from what I gather, this is one of their “High Power” series. Funny, though – the label says “PEAK 500W”. So what is the continuous rating? No one knows, I suppose. But at least we get Active PFC and a ball bearing fan. Also the promise of two 12V rails. But let’s remove the cover and find out what this PSU really hides inside.
Initial impressions: not bad at all. Lots of components and well-packed in there. However, you can tell this is an old design from 2005 – not just because the PCB says so, but also because of that add-on APFC board mounted on the primary heatsink. Clearly, this is from a time before APFC was standard in PSUs.

So let’s have a look at that APFC board too:
Yup, this is definitely an old design “retrofitted” with an APFC board, as one can tell by the input capacitors, which are two 250V, 680 uF Teapo LXK caps (i.e. equivalent to a single 500V, 340 uF primary cap). I didn’t measure how high the APFC boosts the voltage, but obviously it has quite a bit of headroom on the voltage. (If the APFC is tweaked to boost to 450V, those caps will hold approximately the same energy as a single 470 uF cap charged to 380V.)

Also, I forgot to mention – the APFC controller is a UCC3818N, and the 7812 linear regulator is most likely for its supply voltage.

Next, a picture of the secondary side:
Ugh, that tan crap glue is everywhere. At least it’s mostly on the secondary side, though, and not much on the primary. When I see it on the primary side, that’s when I get worried about it causing blow-outs. Other than the glue, it doesn’t look bad. Lots of components and the output toroids are quite big with thick wire. Output caps are mostly Teapo SC, but they are big too, so hopefully won’t be under too much stress. PWM controller is a SG6105d and that daughterboard contains a LM339 quad-comparator. Not sure what the LM339 does – protections, perhaps? It may also have one of its comparators used for fan control, so who knows. Speaking of fans they are two 80 mm Superreds: CHA8012CBS-A(E) (12 V, 0.17 A) and CHA8012BS-M(E) (12 V, 0.12 A):

And finally, the solder side:
Looks alright. Separation between traces on primary is okay too.

So here is the detailed break-down of the PSU…

APFC controller: UCC3818N
APFC Vcc regulator: L7812C
PWM controller: SG6105d
Additional Protections (not sure which exactly): LM393
-5V rail regulator: L7905

Primary Side
*Receptacle with built-in filtering
* five 3.3 nF safety approved Y2 caps (including 2x in receptacle filter)
* four X2-class safety approved caps (0.1 uF in IEC receptacle and 0.22 uF on board + 2 others I couldn’t read their value.
* three CM chokes (one in IEC receptacle is 0.3 mH)
* 6 or 8 Amp –rated bridge rectifier (can’t read part info)
* one MOV between L&N, and one NTC thermistor (can’t read info)
* input wiring rated for 600 V, 18 AWG
* APFC transistors: two 11N60
* APFC diode: BYC10600 diode
* primary input filter caps: 2x Teapo LXK, 250 V, 680 uF, 25 x 40 mm (dia. x h.)
* H-bridge transistors: two 2SC332_ NPN BJTs
* 2N60B MOSFET for 5VSB circuit (2-transistor design)
* size “39” or “40” main transformer, and size “19” for 5VSB and BJT drive transformers

Secondary Side

3.3V rail:
* mag-amp regulated
* rectifier: SBL4045PT
* filter caps: 2x Teapo SC, 6.3 V, 3300 uF, 10 x 25 mm
* PI coil: 5-turn, 6 mm core, between the two caps
* Min. Load Resistor: 7.5 Ohm, 3-Watt

5V rail:
* rectifier: two D____ in parallel (can’t read their numbers, but they are in TO-3P cases)
* filter caps: 2x Teapo SC, 10 V, 3300 uF, 10 x 30 mm
* PI coil: 5-turn, 6 mm core, between the two caps
* Min. Load Resistor: 100 Ohm 1-Watt and two diodes + 1 Ohm resistor all in series to 3.3V rail

12V rail:
* rectifier: MBR30150P
* filter caps:
- 1x Teapo SEK, 16 V (?), 100 uF (?) , 5 x 11 mm
- 1x Teapo SC, 16 V, 2200 uF, 10 x 30 mm
* PI coil: 20-turn, 6 mm core, between the two caps
* Min. Load Resistor: 600 Ohm (?) 1 or 2-Watt

-12V rail:
* rectifier: two PR3002 diodes
* filter caps: Teapo SEK, 16 V, 470 uF, 8 x 13 mm
* PI coil: none
* Min. Load Resistor: none (output to -5V rail 7905 regulator)

-5V rail:
* rectifier: none – derived from a L7905 linear regulator from -12V rail
* filter caps: Teapo SEK, 50 V, 10 uF, 5 x 11 mm on L7905 output
* PI coil: none
* Min. Load Resistor: 910 Ohms

5VSB rail:
* rectifier: SB340 (?) Schottky diode
* filter caps:
- 1x Teapo SC, 16 V, 1000 uF, 10 x 20 mm
- 1x Teapo SC, 16 V, 470 uF, 8 x 15 mm
* PI coil: 5-10-turn, 5 mm core, between the two caps
* Min. Load Resistor: 47 Ohm, 2-Watt

Lastly, I want to mention that this PSU draws A LOT of power when OFF but plugged in – somewhere around 8-10 Watts, as measured by a P3 Kill-A-Watt meter. I thought the APFC might be fooling my meter. But alas, the PSU gets very warm when sitting OFF, so I would not be surprised if it actually is drawing that much power. Most of it seems to originate from the APFC section, as that side of the PSU is the hottest. I imagine the 2-transistor 5VSB is most likely responsible for drawing 3-4 Watts, and the rest is the APFC circuit. Worst part is, this PSU has Teapo caps everywhere, and Teapo does not like heat at all. So I have no clue how long it will last like that.

I have the PSU running in a PC that I use maybe for a few weeks or so every year when visiting some relatives. When not there, I keep the PC unplugged and stashed away, so perhaps that might help it live longer.

The other thing I have noticed is that Sirtech PSUs have somewhat poor voltage regulation, especially on boot-up. When powering on the PC, I hear an awful lot of squealing for 1-2 seconds before the PSU settles. The output voltages seem to wobble a bit during that time as well. And worst part is, I know it’s not the caps, as I have another PSU built by Sirtech that I recapped, and it acts in a similar way (and even worse, when I filled in an “empty” cap spot).

So what are your thoughts on this Sirtec High Power PSU?
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