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Old 03-09-2015, 09:58 PM   #2230
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Default Page 112: Inno Power (Macron) MPT-301 (MPT-9912p REV-A2)

And here is the smaller brother of that Macron I posted earlier:
Inno Power (Macron) MPT-301 (MPT-9912p REV:A2)

Manufactured August of 2002 according to warranty label.

I picked this up from Craigslist many, many years ago (looking at picture info: 2009 or possibly earlier). As soon as I opened it, I thought, this is a PSU I am going to recap and keep, even though its heatsinks looked quite a bit on the thin side. It sat in my closet for another few years before I finally recapped it, though. But when I did, it was totally worth it – the voltages are stable as a rock, regardless if I use this PSU on a 5V-based or 12V-based PC. Thus I ended up using it both as a main PSU in one computer and a test PSU for many others.

So, here is a picture of the case below (click link for new tab). Note the “FAN DOES NOT RUN POWER OUT ‘OK’ 11/05” writing – this is how I found the PSU. And indeed the fan was stuck. However, I am guessing someone continued to use this PSU even with the stuck fan for a little bit, judging by the “POWER OUT ‘OK’” .

Moving onto the label:
Again we see a “NO FAN” user note, besides the typical Macron font. Ratings are rather fair (as you will read in a bit about the rectifiers used). Also, I can’t help but notice the goofy-looking UL logo – why is that? I know these Macron PSUs are legit when it comes to safety. Yet, the logo looks quite botched. Oh well… we care more about the “guts” than the label anyways, right?

And that’s where we are going… some internal pictures – firstly, from the top.

Again, we have a familiar 3-transformer, half-bridge sight we just saw in the other Macron PSU. Ah, but aren’t those bulged Fuhjyyus an eye sore? Keen eyes may have also noticed a slight darkening around the far side of the secondary heatsink – I wonder why?

Primary Side / Input
Actually, I will tell you what is not visible in this picture: a daughterboard soldered to the AC receptacle. With that said, this is what is on the primary:
* 2x LGU GS-L safety X caps across the AC (0.47 uF and 0.22 uF) – one on AC daughterboard
* 4x safety Y caps (with proper agency stamps and approvals!) – two on AC daughterboard
* Two input EMI/RFI chokes; 20 AWG, 600V wiring (nice thick wires, again)
* RS606 bridge rectifier (rated for 6A @ 75C case T. and 800V reverse DC voltage).
* Two Fuhjyyu LP 200 V, 470 uF caps. Forgot to measure those back when I borrowed a ESR Micro meter, so I can’t tell if their capacity is legit. But they appear big enough for their capacity, unlike the Fuhjyyu primaries in the MPT-401.
* Two 2SC2625 NPN BJTs capable of 10A continuous current (for the main PS)
SC5027 NPN BJT for the 5VSB supply
* 5VSB is a 2-transistor design without a critical cap
* "35" -size transformer for the main PS and standard "16"/"19" -size transformers for the 5VSB and feedback sections
* 50V, 10 uF caps for the BJT drive circuit on the main PS

Secondary Side / Output
*All 18 AWG, 300 V -rated wires on the output, except the 4-pin CPU connector – it has 20 AWG.

Output rectifiers;
3.3V rail: single SBL3040pt schottky rectifier; regulation is done by a mag-amp circuit
5V rail: single SBL3040pt schottky rectifier
12V rail: single MOSPEC F16C20C ultra-fast rectifier (but I later replaced it with a 20A 100V schottky rectifier)

Output caps:
3.3V rail: two 10V, 2200 uF, 10 mm dia. with PI coil between them
5V rail: same as 3.3V rail, but no PI coil
12V rail: a single 16V, 3300 uF, 12.5 mm dia. cap, no PI coil before it.
-12 rail: single 16V, 220 uF cap with PI coil before it
-5V rail: single 16V, 220 uF cap with PI coil before it
5VSB rail: two 10V, 2200 uF, 10 mm dia. caps with PI coil between them
Sec. Side Aux. Rail: 25V, 470 uF, 8mm cap

Originally, all output caps were Fuhjyyu TNR. I replaced with same capacity on the major rails. 3.3V rail got Panasonic FM, 5V rail UCC KY, 12V rail UCC KZE, and 5VSB rail only a single UCC KY (I kept one of the Fuhjyyus as it was located a bit further from the secondary heatsink and didn’t seem like it got overheated). The -5V rail received a 10mm dia 10V 1000 uF CapXon KM (I know, what a terrible choice!), since I didn’t have enough caps back when I did this PSU. It still seems to be doing “fine” in there, though. And being that the -5V rail is not heavily loaded, I think it should be okay. As for the -12V rail, I again didn’t have any suitable caps at the time, so I just left the lone 220 uF Fuhjyyu cap in there. The Sec. Side Aux. rail did get a new UCC KZE 470 uF cap, mainly because it is used for driving the main PS, so I found it important.

Minimum load resistors for 3.3V, 5V, 12V, -12V, and -5V rails:
10 Ohm, 2W; 25 Ohm, 2W, none, 620 Ohm, 1W, 270 Ohm, 1W
For the -12V and -5V rails, the minimum load resistors are connected between those rails and 5V rather than ground (not sure why , but that's how it's designed).
On this PSU, I actually did swap around some of the loading resistors. 3.3V rail now has what was originally on the 5V rail: i.e. 25 Ohm 2W resistor. 5V rail received a big 100 Ohm 3W resistor (overkill, I know). 12V rail doesn’t have a spot for anything so I left it as is. The -5V and -12V both got 1000 Ohm W resistors IIRC.

Finally, some underside shots:
Just like the MPT-401, the soldering is quite okay and same good primary-secondary side separation.

Fan is a Superred CHA8012BS rated for 0.12A @ 12V. It was completely stuck and extremely hard to turn even by hand. What’s worse, there was no hole and rubber plug under the label on its back like most fan. Instead, there was a plastic plug that was heat-pressed onto the case plastic – no way to open it really… or so you might think .
But I did actually open it. Just drilled the crap off of that plastic . Once the shaft was exposed, I hammered the top (rotor) part of the fan out and cleaned everything. After doing a proper clean on the sleeve bearing, then some parallel groove scratching, then another clean and putting oil, the fan ran like a champ again – and still does to this day ever since I fixed it. No grinding, no whining, no weird noises. It just needed good cleaning and oil. So all in all, I think Superred fans are okay.

And finally, here are a few pictures after all of the work was done:
Nice good Japanese caps almost everywhere (including some small ones). I didn’t replace single every cap, but I did replace the important ones – namely the two 10 uF 50V for the BJT drive, and the one that filters Vcc for the TL494.

And finally, the back of the case with a few mods:
I basically added some holes to allow more air to go underneath the PCB. Hopefully, this should better cool off some of the smaller components that are soldered close to the PCB.

And that’s about everything to know about this PSU . *Whew*, another big post again. I hope you didn’t find it boring .

Last edited by momaka; 03-09-2015 at 10:13 PM..
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