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Old 06-02-2021, 10:05 PM   #1
momaka
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Post Casing Power MPT-301 [PCB ATX9806b-p REV: A3]

This one should make @Pentium4 smile (if he is still reading BCN forums) – I got a new old stock / open box Casing Power MPT-301 PSU on eBay for $4 total.
Casing Power MPT-301 [PCB ATX9806b-p] - box (1).jpg

Yes, it’s a very generic-looking box, but the manufacturer isn’t (at least not back in the days), which is…
Casing Power MPT-301 [PCB ATX9806b-p] - box (2).jpg
Macron Power Technology Co. LTD.

Let’s look at the PSU itself.
Casing Power MPT-301 [PCB ATX9806b-p] - case (1).jpg
Casing Power MPT-301 [PCB ATX9806b-p] - case (2).jpg

The shell/case also appears quite generic, like many “sold-with-the-PC-case” units. However, the shell is well-formed and has decent steel thickness. In terms of output wires, it’s pretty standard for the era: 1x 20-pin ATX main connector, 1x 4-pin 12V CPU, 4x Molex drive, 2x floppy, and 1x AUX 3.3V power connector. Most of these are 18 AWG size, but the 4-pin 12V CPU and AUX connector use 20 AWG wire (and of course, the floppy is 22 AWG.)

Next, the label:
Casing Power MPT-301 [PCB ATX9806b-p] - label.jpg
Does this look familiar now? It should. No, it’s not the same PSU as the ADP MPT-301 that I recently recapped. It’s more like this Inno Power PSU I posted a while back.

Part of the reason why I got the MPT-301 here so cheap was this:
Casing Power MPT-301 [PCB ATX9806b-p] - case (3).jpg
Not sure if this was caused by a drop or something else, but the grille on the rear fan is pretty mangled… though the PSU can still be mounted in a case and there is no other damage anywhere else.

The other reason the PSU was so cheap was… well, it’s a bit of a long story, as usual. But in fewer words, the eBay seller I bought it from messaged me to say they couldn’t ship the PSU the same day (which I never really asked for, so no problems ) and instead would likely be shipped either the next day or the day after that. I replied, saying that’s not an issue at all, since the PSU was intended for a retro PC / hobby project and thus wasn’t needed in a hurry. Then the seller messaged me back and curiously asked about my retro PC build. So we exchanged a few messages back and forth about old PC hardware. Turns out the seller also had intended this PSU for a retro PC build. But the motherboard he had seems to have burned out from the previous PSU (and likely from bad caps. ) There’s probably more to follow on this story, but I’ll leave that for another thread/post, as it pertains more to motherboards.

Anyways, now let’s look inside this particular MPT-301 unit.
Casing Power MPT-301 [PCB ATX9806b-p] (1).jpg
Casing Power MPT-301 [PCB ATX9806b-p] (2).jpg
Casing Power MPT-301 [PCB ATX9806b-p] (3).jpg

EMI/RFI board:
Casing Power MPT-301 [PCB ATX9806b-p] - EMI-RFI board.jpg

Primary Side:
Casing Power MPT-301 [PCB ATX9806b-p] (4).jpg
Casing Power MPT-301 [PCB ATX9806b-p] (5).jpg

Secondary Side:
Casing Power MPT-301 [PCB ATX9806b-p] (6).jpg
Casing Power MPT-301 [PCB ATX9806b-p] (7).jpg

As you can see, it DOES look very much identical to the Inno Power I linked to above. However, it actually isn’t the same. The PCB on this one says ATX9806b-p whereas the Inno Power (and a Macron Power MPT-401 I also posted) has a PCB marked with ATX9912p. There are minor differences between the two, though the design and layout is nearly the same.

Some of you may (again) still question this PSU based on the generic looks. But let’s not forget it’s from 2003. Back then, this kind of build quality was actually considered on the decent side. Sure it’s not built like the older Delta and HiPro units with oversized heatsinks and big rectifiers. But it’s also quite far from being a gutless PSU.

So let’s talk about the good things here:
- PSU has a complete EMI/RFI input filter
- connector on the PCB for the AC input wires
- overall good-sized heatsinks and output toroid inductors
- space for a few 12.5 mm diameter caps on the output
- 3-Amp rated 5VSB with its own TO-220 rectifier bolted to the secondary HS.

Next, the mediocre stuff:
- half-bridge design with NPN BJTs and secondary-side PWM (reliable but outdated)
- main transformer uses EI-33 core (instead of the larger EI/ERL-35)
- protection fuse is a glass one (so it needs to be either heatshrink wrapped or better yet, be a ceramic one)
- bridge rectifier consists of individual 1n5406 diodes (though they should be adequate for the job with active cooling from the fan)
- the heatsinks could have been bigger, as there is a lot of empty space left inside the case
- TO-220 BJTs on the primary (2SC5679 – please anyone tell me if you can find a datasheet for them), which might be cutting it a bit too close for 300 Watts continuous (maybe 300 Watts peak for a short period… though I still wouldn’t feel too comfortable with that, given the heatsinks.)
- 20 AWG wire on the AC input side
- 2-transistor 5VSB with feedback - kind of “meh” today, though considered OK back then. At least this one doesn’t have a “critical” cap.

And for the not-so-good:
- Three of the five Y2-class caps for the EMI/RFI filter are just regular 1kV ceramic caps (so UL hi-pot testing likely won’t do well here)
- the capacity of the output caps is a bit on the low side (only 2200 uF for the 3.3V rail)
- there are no PI inductor coils between caps on the output… though I don’t know if that counts as “not good” here, since the PSU could have been designed without them. The Inno Power also doesn’t have them on the 12V and 5V rails by design, IIRC
- 12V rectifier is only a F12c20c part – therefore, that “15 Amp” rating for the 12V rail on the label is probably a “peak” value and not continuous (which surprises me, as Macron doesn’t usually over-rate their PSUs.)
- BAD CAPS! Perhaps hard to see, but take a look again at that picture of the secondary side – one of the 10 mm caps on the lower-left side of the picture is bulging ever so slightly. To be honest, though, I was expecting much worse from this PSU, as Macron Power often used some of the worst garbage cap brands in their PSUs. In this one, it’s mostly CS-logo caps, which IMO are “medium-bad” for these PSUs (with the worst being GL –branded caps, and the “best” being Fuhjyyu and CapXon ) In fact, one of the reasons I bought this PSU was because I was curious how bad the caps inside it must be and just felt like saving another older PSU.

So my overall thoughts: it’s still a pretty decent PSU for its time, though perhaps a slightly more “cost-oriented” version of the Inno Power I have, given some of the items outlined above. What really bothers me the most are the 1kV ceramic caps in the Y2 filter spots, as I think this may not pass UL tests. Then again, looking at the label, the UL logo looks very “botched” (to say the least) along with many of the other safety marks. Besides the ceramic “Y2” caps, everything else looks like it should pass UL tests easily. The strange part is that the Inno Power PSU also has the same dodgy safety marks, but that one does actually use proper Y2 and X2 caps throughout. I think Macron just didn’t do their label right, because IIRC, back when the UL site still had searchable listings, I do recall seeing the MPT model of PSUs there. Also, the background picture on the green box of the PSU above does show the Y2 caps as being ceramic ones (there’s the same picture on the back of the box, but more clear.) So it’s not like Macron was trying to hide anything – that background picture does appear to be of an actual Macron PSU. On that note, they do show a PSU on there with slightly better heatsinks (and a cut-out on the primary for a PPFC, I think.) But all in all, what’s shown and what’s inside isn’t too far apart. I just don’t understand the part with the ceramic Y2 caps. Definitely a goof up there!

Components aside, here is a fan shot:
Casing Power MPT-301 [PCB ATX9806b-p] - fan.jpg
Unfortunately, the promise on the box of a ball bearing fan was a false claim. This is a classic non-sealed Power Logic *sleeve bearing* fan. At least these are actually very reliable fans, especially with a fan speed control (which this PSU does have.) So I can’t say I’m that disappointed. The fan actually feels very solid.

And to finish on a positive note, let’s see the solder-side:
Casing Power MPT-301 [PCB ATX9806b-p] - PCB.jpg
If there is one thing Macron got right, it’s their soldering, IMO. No complaints here whatsoever.

Needless to say, this PSU will be recapped. I pulled most of the output caps out and checked them on the GM328 tester.
Casing Power MPT-301 [PCB ATX9806b-p] - original caps.jpg

Basically, only the CS-logo 10V, 2200 uF caps in 10 mm diameter turned out to be bad, as they all showed above-normal (40%+) capacitance, suggesting their electrolyte is starting to break down (and indeed that must be so, judging from the bulged one.) I expected to see the same with all of the other CS-logo caps, but surprisingly they still showed good capacitance and ESR. Time will tell how long those will last, though.

The primary G-Luxon 470 uF caps are also still good (or at least the one I tested) - but that I expected. And they are not lying about their capacitance either.
Casing Power MPT-301 [PCB ATX9806b-p] - primary cap.jpg

Now for the parts list…

ICs:
TL494 (PWM controller), LM339 (quad comparator used as output supervisor)

Wiring:
* 600V, 20 AWG input wiring
* 300V, 18 AWG output wiring (except 4-pin CPU and AUX, which are 20 AWG)
* Output connectors: 20-pin ATX, 4-pin 12V CPU, 4x Molex drive, 2x floppy, 1x AUX

Primary Side:
* Input Filtering: two X2-class caps (1x 0.47 uF, 1x 0.22 uF), two Y2-class caps (2.2 nF) and three 2.2 nF 1kV ceramic caps in Y2 spots, two CM chokes
* Input protection: 6.3A 250V glass fuse (F-type), SCK 053 NTC inrush current limiter
* 4x 1N5406 diodes for a bridge rectifier
* 2x G-Luxon SM, 200V, 470, 22x40 mm, 105°C caps
* 2SC5027F-R NPN BJT (TO-220) + 2sc945 BJT (TO-92) for 2-transistor 5VSB circuit
* 2x 2SC5679 NPN BJTs (TO-220) in half-bridge configuration for main PS
* 2x PCE-TUR, 50V, 10 uF, 5x11 mm caps for BJT drive coupling
* 1 uF 250V PP metal film cap for H-bridge
* main PS snubber network: 47-Ohm 3 Watt resistor + 4.7 nF 1kV ceramic cap
* EI-33 main PS transformer, EE16 BJT driver transformer, EE16 5VSB transformer

Secondary Side:
* 5VSB
*** 2x CS logo, 10V, 2200 uF, 10x20 mm with PI coil (5 mm core, 6 turns, 20 AWG)
*** F06c20c (TO-220) fast-recovery rectifier

* 3.3V Rail
*** 1x CS logo, 16V, 2200 uF, 12.5x20 mm cap without PI coil
*** 1x SBL1640CT (TO-220) Schottky rectifier
*** dual mag-amp saturation toroids and no load resistor

* 5V Rail
*** 2x CS logo, 10V, 1000 uF, 10x18 mm caps without PI coil
*** 1x CS logo, 10V, 2200 uF, 10x20 mm cap without PI coil
*** 1x SBL3040pt (TO-247) Schottky rectifier
*** 22-Ohm 2 Watt load resistor

* 12V Rail
*** 1x CS logo, 16V, 2200 uF, 12.5x20 mm cap without PI coil
*** 1x F12c20c (TO-220) fast-recovery rectifier

* -12V Rail
*** 1x CS logo, 16V, 220 uF, 6.3x11 mm with PI coil before it
*** 3x FR104 diodes (2x for rectification, 1x as a series voltage dropper)
*** 620-Ohm 1 Watt load resistor connected to 5V rail (instead of ground)

* -5V Rail
*** 1x CS logo, 16V, 220 uF, 6.3x11 mm with PI coil before it
*** 2x FR104 diodes for rectification
*** 240-Ohm 1 Watt load resistor connected to 5V rail (instead of ground)

Last edited by momaka; 06-02-2021 at 10:11 PM..
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Old 06-02-2021, 10:17 PM   #2
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Post Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - 5VSB circuit

And here is the schematic for the 2-transistor self-oscillating 5VSB circuit of the Casing Power MPT-301 PSU:


Unlike 2-transistor 5VSB circuits in other PSUs, this one doesn’t bias the main switch device, QA2, (an 2SC5027 NPN BJT) from the rectified +320V DC bus, but rather from the Live line through a resistor-cap series network (which I’ve never seen done before.) Thus, at first power-up, it looks like the main switch is pulsed ON and OFF a few times with whatever the line frequency is (50 or 60 Hz) until the primary-side auxiliary winding takes over. My guess for why this is so, is perhaps because there is also no negative feedback taken from the main switch’s Emitter resistor, R00. In other 5VSB circuits I’ve seen, there is usually a small resistor that gives negative feedback from that Emitter resistor to the Base of the driver switch device (in this case, QA1 – a 2SC945 NPN BJT) so that the main switch device can turn OFF and self-limit its switching until the primary-side aux. winding runs at normal steady-state. I think the implementation of the Casing Power 5VSB circuit might be more clever, though, because even in the event of an open primary aux. winding, the main switch device may self-limit in a more controlled manner than a constant DC-bias of a resistor, as done in other 5VSB implementations. Or maybe not?

Also note the 2-transistor circuit of the Casing Power PSU doesn’t have a “critical” / startup electrolytic cap filtering the primary-side auxiliary winding. Therefore, this PSU may be less prone to over-voltage failure over time… or at least not from that component failing. However, I honestly don’t think anymore that any 2-transistor self-oscillating circuit is 100% safe, because as I’ve seen recently in another PSU, bad electrolytic filter caps on the 5VSB output side can still cause the 5VSB to go crazy and nuke itself. So as always, consider these 2-transistor 5VSB circuits somewhat more risky and less likely to go down nicely.

In terms of load-testing the 5VSB, I didn’t go too much in-depth. With no-load, the 5VSB sits at 4.99-5.00V exactly, and the PSU draws about 1.8 Watts from the wall according to my Kill-A-Watt. That’s not bad for a 2-transistor self-oscillating design. In contrast, the Channel Well –built ADT MPT-301 (note it’s *not* a Macron-made PSU, despite what its label suggests) from this thread pulled 3.3 Watts from the wall with no-load attached – and that’s after the recap and removal of the 10-Ohm load resistor (which was replaced with 2x 100 Ohms in parallel.) Of course, the Casing Power 5VSB circuit does not have any load resistors on its output, so that probably contributed a fair deal as to why it pulled less power.

With a 0.35 Amp load on the 5VSB, the Casing Power PSU drawing 5.3 Watts / 10.3 VA from the wall. Efficiency-wise, that comes out to a measly 33%... which, again, actually isn’t too terrible for a 2T-circuit. In fact, as a comparison, the recapped and modded CWT ADT PSU drew 5.8 Watts from the wall with the same load… or only 0.5 Watts more than the Macron. Not coincidentally, that extra 0.5 Watts is exactly how much the two parallel 100-Ohm load resistors draw @ 5V. So if we account for that, the 5VSB circuit in the Macron performs identical under load to that of the CWT.

Next, I tried a 2.2 Amp load on the 5VSB of the Casing Power PSU. With that, the output voltage dropped down a bit to 4.91V, which is well within spec. Nothing inside the PSU got too hot after 5 minutes, except of course, the primary heatsink on which the 5VSB main switch is mounted to. That heatsink always gets quite warm, though (when the PSU is in soft-off mode), regardless if the 5VSB was loaded or not. I forgot to record how much power the PSU drew from the wall with the 2.2A load. But if I remember correctly, the efficiency increased somewhere to around 45-50%. Those are still pretty poor power conversion efficiency numbers, but normal for 2-transistor flyback designs. In contrast, modern PSUs (at least known good brands with 5VSB controller chips) will typically draw less than 1 Watt (even less than 0.3 Watts nowadays) from the wall with no load on the 5VSB and usually achieve no less than 50-70% efficiency at other loads.

Lastly, it’s worth noting that the above tests were done after recapping the 5VSB circuit. That is, I put one new Rubycon YXJ, 10V, 2200 uF cap in place of the 1st filter cap on the 5VSB output filter and replaced the 2nd filter cap (originally a CS logo 10V, 2200 uF) with the 16V, 2200 uF cap from the 12V rail. This change was needed, because all of the CS 10V, 2200 uF, 10 mm caps were starting to fail, as mentioned above.
Attached Images
File Type: jpg Macron Power ATX9806b-p REV-A3 5VSB circuit.jpg (152.2 KB, 81 views)

Last edited by momaka; 06-02-2021 at 10:25 PM..
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Old 06-02-2021, 10:23 PM   #3
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Post Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

Next up: a few load tests…
Test #1: ~6 Amps on 12V, 2.5 Amps on 5V, 1.6 Amps on 3.3V
Test #2: ~12 Amps on 12V, 5 Amps on 5V, 1.6 Amps on 3.3V
Test #3: ~1.7 Amps on 12V, 10 Amps on 5V, ~2.9 Amps on 3.3V
Test #4: ~1.7 Amps on 12V, 20 Amps on 5V, ~2.9 Amps on 3.3V

But before that, I had to do a quick recap as it just didn’t seem like a good idea to load the PSU when there are bad caps in there. To keep the PSU as original as possible for the load tests, I swapped only a few caps in key spots.

The recap consisted of the following:
12V rail: CS-logo 16V, 2200 uF, 12.5x20 mm ---> (used) Nichicon PW with same V and uF.
5V rail: 1x bulged CS-logo 10V, 2200 uF, 10x20 mm ---> Rubycon YXJ with same V and uF.
-12V rail: CS-logo 16V, 220 uF, 6.3 mm dia.---> Nichicon PM 16V, 220 uF, 8 mm dia.
5VSB rail: 2x failed (but not bulging) CS-logo 10V, 2200 uF, 10x20 mm ---> 1x Rubycon YXJ with same V and uF (for 1st filter spot) and 1x CS-logo 16V, 2200 uF cap from the 12V rail (for 2nd filter spot - I just barely managed to squeeze it in there.)
Casing Power MPT-301 [PCB ATX9806b-p] - temp recap v1.jpg

Only after this I ran my load tests, while also abusing the PSU with a low AC input voltage (through a series heating element) to simulate worst-case AC line input scenario. These were the voltage output results:

12V-heavy load (test #1)
Casing Power MPT-301 [PCB ATX9806b-p] - load testing (2).jpg

12V-heavy load (test #2)
Casing Power MPT-301 [PCB ATX9806b-p] - load testing (3).jpg

5V-heavy load (test #4)
Casing Power MPT-301 [PCB ATX9806b-p] - load testing (4).jpg

As you can see, the PSU did OK with the 12V-“heavy” load tests, but went out-of-spec on the 2nd 5V-heavy test (20 Amps on the 5V rail), where the 12V rail went up to 12.7V. So despite being an older PSU, it didn’t do particularly well with a heavier load (100 Watts) on the 5V rail. However, with a 50 Watt load (10 Amps on the 5V rail), it was fine. Thus, it may be able to handle most retro 5V-heavy systems OK, so long as they don’t load the 5V rail too much (or perhaps at least load the 12V rail a little more with several HDDs.)

Efficiency-wise… this PSU seems to be pretty standard from what one could get with a half-bridge consumer design from the early 2000’s – i.e. ranging between low and mid-70’s % for most tests. AC input varied between 90-100V AC, depending on the series heating element used (700W or 1400W), but the AC from the wall was a steady 120V.
Test #1 (with 700W series element on AC input): 91V AC to PSU and ~92.93 Watts on DC side… efficiency: roughly 75-80% efficiency
Test #2 (with 1400W series element on AC input): 90V AC to PSU and ~177.43 Watts on DC side… efficiency: roughly 68.5-73% efficiency
Test #3 (with 700W series element on AC input):… didn’t record data
Test #4 (with 1400W series element on AC input): 101V AC to PSU and ~133.05 Watts on DC side… efficiency: roughly 71-75.6% efficiency

While doing these load and efficiency tests, on #2 and #4 I briefly switched the series heating element from 1400W to 700W, further dropping the AC input to see how the PSU would react. As previously found with my KDM PSU, it seems that these half-bridge PSUs don’t actually shut down with a low line AC input, but instead continue to try working. This is obviously not desirable as it probably causes a lot of stress on the primary side (and hence why I run this test only briefly, as I haven’t tried to see what would happen if I ran it for an extended period of time… but I will on a junker PSU some day. ) In the case of the Casing Power PSU here, on test #2, the 12V rail dropped to about 10.3 Volts. And dropping the AC input the same way for test #4, the 12V rail dropped from 12.7V to 12.02V – nicely in spec… until one looks at the 5V rail (where the load was), which dropped out of spec from 4.96V to 4.66V. In both of these cases, however, at least the PSU’s Power Good logic operated correctly and went low to signal that it wasn’t outputting correct voltages. It would be better, of course, if the PSU did that and then shut down. So I guess that’s not just a quirk with the KDM PSU, but with all half-bridge PSUs, as I tested a few others, and they all acted exactly like this.

On a different note, I also decided to pull out my type-K temperature meter and see how hot things got inside this MPT-301. Basically, I had the top cover of the PSU properly installed, but just without the screws. Then, after running each test for ~10-15 minutes, I shut off AC power, pulled the top cover off, and took measurements of various components of interest – namely the primary and secondary heatsinks, 3.3V and 5V/12V output toroids, 3.3V mag-amp saturation coils, and the output caps.

What I concluded from that is the secondary heatsink was usually the hottest-running part (actually, the NTC thermistor on the AC input got much hotter than anything, but that’s normal for these.) Of course, how hot it got depended on the load. For example, in 12V-heavy test #1, it only got up to 50°C. Meanwhile, the primary heatsink barely touched 40°C. And from the output inductors, really only the mag-amp saturation coils for the 3.3V rail got somewhat warmer than the other components, reaching around 45-50°C. As for the 5V/12V main toroid, 3.3V filter toroid, and output caps – nothing really got over 40-45°C (most caps remained cool at around 30-35°C.) For 12V-heavy test #2, the temperatures didn’t really change much compared to test #1, except the secondary heatsink – it got considerably hotter (about 60°C) due to pushing the F12C20 rectifier for the 12V rail right down to its maximum rating at 12 Amps. 5V-heavy test #2 produced similar temperatures and the secondary heatsink again hovered in the low 60’s °C due to the high current through the 5V rail rectifier. However, by far the worst was a modified version of 12V-heavy test #2, where I rewired my load tester and reduced the current on the 5V rail from 5 Amps to about only 2.5 Amps. Intuition might suggest that things should have ran cooler… but that’ wasn’t the case for the output toroid, which got mighty-hot due to the difference in cross-load currents and attempting to equalize the output voltages. It easily hit 65°C after only a few minutes of operation. So it’s quite possible it could reach 70-75°C in a not-so-well ventilated case and after running for a good few hours. Goes to show what harsh cross-loading can do!

Although my PSU “load tester” is still not finished (actually, not even past the beginning stage of construction ) and thus not able to load my PSUs more… I have to say I’m overall satisfied with how this PSU performed. All I need now is an oscilloscope to check ripple and noise output… but I don’t know if I will ever do that. :\
… and kind of sad to write all these walls of text and not even have a single scope shot, isn’t it? On that note, I hope this isn’t considered a complete waste of time and e-space. Recapping info/diagram coming next, so perhaps that may redeem things a bit.
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Old 06-02-2021, 10:40 PM   #4
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Cool Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - recap & mods

When it comes to recapping of this PSU, I’ll jump straight to the diagram here:

It’s a very straight-forward PSU to recap and super-easy to work on, thanks to Macron putting connectors for the fan and AC input on the PSU board, making it easy to take apart.

After doing the load tests above, I did a slightly more complete recap. Namely I replaced the single 3.3V rail CS-logo 16V, 2200 uF cap with a United Chemicon LXV, rated for 6.3V and 3900 uF. I figured the boost in capacitance could benefit the 3.3V rail. On the 5V rail, there are 3 caps originally: 2x 1000 uF and 1x 2200 uF. I had already replaced the 2200 uF CS-logo cap with a Rubycon YXJ. But then I decided to also replace one of the 1000 uF caps with another 2200 uF Ruby YXJ. So the total capacitance now on the 5V rail is 5400 uF (compared to 4200 uF before.) And finally, I also changed the CS-logo 25V, 470 uF cap on the secondary side auxiliary rail with a United Chemicon KZE of same voltage and capacitance ratings. All other caps are still the original ones, as I am currently out of stock for the small caps. On that note, in addition to the electrolytic caps listed in the 1st post, there are 3 more small caps on the secondary side for the logic circuits. These are, I think, 1x 10 uF cap, 1x 4.7 uF cap, and 1x either 1 uF, 2.2 uF, or 4.7 uF cap – all rated for 50V. Of course, 25V or 35V ratings should work too. So here’s a look at how my recap came out:
Casing Power MPT-301 [PCB ATX9806b-p] - recapped and modded v2 (1).jpg

Casing Power MPT-301 [PCB ATX9806b-p] - recapped and modded v2 (2).jpg

As for modding, there are several things I did to this PSU. Starting with the 2nd picture above, I changed the no-load output resistors on the 3.3V and 5V rails. In particular, the 3.3V rail had none and the 5V rail had a 22-Ohm, 2W resistor. I added a 100-Ohm ½ W resistor on the 3.3V rail (since there is a spot for a resistor on the PCB.) Meanwhile for the 5V rail, I removed the 22-Ohm resistor and replaced it with another 100-Ohm ½ W part. So far, the PSU seems to be OK with this change – at least when running it with a load. Perhaps with nothing attached on the PSU outputs, the rails might go a bit “wonky”… but I am intending to use this PSU in a PC, so that shouldn’t be the case here.

Also notice in the 2nd picture that one of the rectifiers now has a pink thermal pad behind it. No, I didn’t just do a thermal pad “upgrade”. Rather, I swapped the 12V rail’s rectifier (previously an F12C20C) with an STTH1602ct that came from this Delta DPS-300ab-15b PSU (along with the pink thermal pad.) So now this PSU could technically meet its current rating specs on the label for the 12V rail.

Next on the list was that bent part on the back of the case shell near the fan.
As posted above, the -before-:
https://www.badcaps.net/forum/attach...9&d=1622692889

And the -after-:
Casing Power MPT-301 [PCB ATX9806b-p] - fixed case.jpg
It’s not perfect, but not bad either for the ~10-15 minutes of work I put in it (this was done back in March when it was still cold in the garage, so couldn’t spend too much time there without my hands freezing.)

Then eventually I also added more ventilation holes to the case shell.
Casing Power MPT-301 [PCB ATX9806b-p] - recapped and modded v2 (5).jpg

Last but not least, I’ve always thought about doing this to my Inno Power MPT-301, but never really committed to it:
Casing Power MPT-301 [PCB ATX9806b-p] - recapped and modded v2 (3).jpg

Casing Power MPT-301 [PCB ATX9806b-p] - recapped and modded v2 (4).jpg

It might not seem significant, but it does actually add quite a bit of surface area to the secondary heatsink (almost doubles it.) For good heat transfer, I did couple the two aluminum surfaces with white ceramic thermal compound. The screw on one end ensures that the two surfaces are tightly against one another. But for redundancy, that steel wire piece also adds pressure on the two heatsinks. I then did a 2nd quick re-iteration of the load tests, and the secondary heatsink ran about 3-5C cooler on average. Both the top and bottom part were at the same temperature, so the thermal transfer between the two is working well.

And that’s all I did to this PSU… so far. It is boxed back up and ready for use. I have several systems in mind that this might go in.
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Old 06-03-2021, 11:11 AM   #5
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3]

I'd guess the realistic do-it-all-day output power for that at around 200W. Unless the fan is providing a hurricane of cooling air, those heatsinks really are too insubstantial for 300W. The cheap fake Y-caps are glaringly obvious. The 470uF input lytics probably are about right for 250W, but heatsinks and the smallish main transformer core aren't.

I didn't find a datasheet for the 2SC5679 switch transistors, but did learn that Fuji Electric discontinued them in 2013. Interestingly, the PCB is laid out to accommodate larger TO-3P or TO-247 transistors.

I noticed that the box advertised that it had a ball bearing fan, but the fan is labelled "Sleeve Bearing".

With your partial re-cap and some real Y-caps you might have a very decent 200W P/S capable of handling occasional surges to 250W. If its 5VSB really is capable of 3A, that was top end for when it was built and probably is still pretty typical.
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Old 06-03-2021, 12:50 PM   #6
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

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Originally Posted by momaka View Post
All I need now is an oscilloscope to check ripple and noise output… but I don’t know if I will ever do that. :\
… and kind of sad to write all these walls of text and not even have a single scope shot, isn’t it?
Thread fixed
This is with a 10Ω load on 5VSB, so only 0.5A but still excellent results.
Oh, never mind the PSU on the right, that is just acting the load as it was the first decent resistor I came across
And momaka: great writeup, I did read it all because I noticed it is the same PSU that I posted about here, so that is what this scope shot shows
P.S: Mine has legitimate Y caps and what looks like much larger transformers.

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Old 06-10-2021, 10:23 PM   #7
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

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Originally Posted by Per Hansson View Post
Thread fixed
This is with a 10Ω load on 5VSB, so only 0.5A but still excellent results.
Thank you for posting this!
Yeah, your 2x 3300 uF Rubycon MBZ caps will certainly keep the 5VSB circuit nice and quiet on ripple... though even the stock 2x 2200 uF are probably already doing a really good job. Most 5VSB circuits I've seen from Delta, HiPro, and LiteOn that are rated for 2-2.5 Amps typically have 1x 2200 uF and 1x 470-1000 uF. So 2x 2200 uF for 3 Amps on a flyback design seems quite appropriate, if not a bit on the generous side. Of course, the original CS-logo caps (or other crap stock brands that come with this PSU) don't have very good low ESR spec, so that's probably another reason for the higher capacity / bigger can.

Quote:
Originally Posted by Per Hansson View Post
Oh, never mind the PSU on the right, that is just acting the load as it was the first decent resistor I came across
That looks like a BTX -model Deer/L&C... and probably one of their "better" builds, given that it has EMI/RFI input filtering.

Quote:
Originally Posted by Per Hansson View Post
And momaka: great writeup, I did read it all because I noticed it is the same PSU that I posted about here, so that is what this scope shot shows
P.S: Mine has legitimate Y caps and what looks like much larger transformers.
Nice!
Going through that thread and the links in there, it seems a lot of other people had this unit or it's slightly updated brother based on the ATX9912p PCB. I guess it was fairly popular PSU back in the day... and not a bad one, save for the crappy cap choices, of course.

Quote:
Originally Posted by PeteS in CA View Post
I'd guess the realistic do-it-all-day output power for that at around 200W. Unless the fan is providing a hurricane of cooling air, those heatsinks really are too insubstantial for 300W.
Agreed!
I think Macron pretty much printed the same label for all of the MPT-301 units and called it a day, when in reality, some of the MPT-301's built with "lesser" parts like this one really should have been downgraded to 200W continuous / 250W max. I suspect this PSU might provide 300W peak for a few very short moments... but overall consider it risky. At low line voltage (and thus higher transformer currents), I suspect the main transformer may saturate and take out the primary or the primary may just go out by itself even before then.

As for the fan - it does actually push quite a bit of air. I think it's running around 6-7V in idle and increases slightly when the PSU gets hotter (though I didn't measure how the fan voltage is impacted - perhaps a curious test for another day. )

Quote:
Originally Posted by PeteS in CA View Post
I didn't find a datasheet for the 2SC5679 switch transistors, but did learn that Fuji Electric discontinued them in 2013. Interestingly, the PCB is laid out to accommodate larger TO-3P or TO-247 transistors.
Hmmm... perhaps a datasheet was never released on the internet? That means, if I had to guess, these are somewhat similar in specs to 13007's or a tier lower.

As for the PCB layout... my other MPT-301 (the Inno Power) and the MPT-401 (400W Macron) both have TO-3P main BJTs. So this Casing Power is definitely a cheaper / lower-end version.

Quote:
Originally Posted by PeteS in CA View Post
I noticed that the box advertised that it had a ball bearing fan, but the fan is labelled "Sleeve Bearing".
Yup.
That's why I showed the box and the fan.
At least the PSU wasn't terribly grossly over-rated, like some of the really nasty 100-200W -capable gutless wonders still sold today with the promise of being 600+ Watts. Ugh

Also, that PowerLogic fan is actually a really decent fan - very quiet for the amount of air it pushes.

Quote:
Originally Posted by PeteS in CA View Post
With your partial re-cap and some real Y-caps you might have a very decent 200W P/S capable of handling occasional surges to 250W.
Oh, I forgot to mention in the above walls of text on the recap - I did actually replace the non-approved ceramic "Y"-caps with real ones... or 2 out of 3, anyways. Basically, I replaced the one between Live and Ground and the one between rectified negative primary bus and Ground, as these are the ones that can present danger to the user in the case of a failed Ground and one of these caps being bad. The only original "Y" cap I didn't replace is the one between Neutral and Ground, since it won't present a safety issue - not unless Live and Neutral are switched... which won't be the case, as we have polarized plugs in the US. In Europe, though, with countries that use the Schuko plug - definitely all non-approved Y-caps need to be swapped. Interestingly enough, the EMI/RFI PCB soldered to the input power connector does contain 2x real approved Y2 caps.

Quote:
Originally Posted by PeteS in CA View Post
If its 5VSB really is capable of 3A, that was top end for when it was built and probably is still pretty typical.
I think I did a quick and "unofficial" test on the 5VSB on my Inno Power PSU long time ago, and indeed it could provide 3 Amps.
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Old 06-12-2021, 02:31 AM   #8
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

Quote:
Originally Posted by momaka View Post
That looks like a BTX -model Deer/L&C... and probably one of their "better" builds, given that it has EMI/RFI input filtering.
It's actually the PSU from this old thread that I fixed last weekend and posted about here just now

Quote:
Originally Posted by momaka View Post
Agreed!
I think Macron pretty much printed the same label for all of the MPT-301 units and called it a day
Oh for sure, go back to that thread where I post this:
"Also if you want to see something EXTREMELY funny look at this old post by me, of a PSU with an identical model number, but higher ratings on all the outputs..."
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Old 06-19-2021, 01:11 AM   #9
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

Quote:
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This is obviously not desirable as it probably causes a lot of stress on the primary side (and hence why I run this test only briefly, as
I hope that when you this type of testing that you do a complete write up about how you did it

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I haven’t tried to see what would happen if I ran it for an extended period of time… but I will on a junker PSU some day.
I would be very interested in the results of this type of testing
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Old 09-15-2021, 07:21 AM   #10
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

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Originally Posted by Per Hansson View Post
Oh for sure, go back to that thread where I post this:
"Also if you want to see something EXTREMELY funny look at this old post by me, of a PSU with an identical model number, but higher ratings on all the outputs..."
Hmmm, just stumbled upon this after trying to catch a few details of my recap...

So, the Q-TEK ADT-350 in the last link above - that's not actually a PSU made by Macron. It's a CWT ISO series, and probably one of their most gutless ones. See this thread on the CyberLink CWT-320ATX:
https://www.badcaps.net/forum/showthread.php?t=39222

Quote:
Originally Posted by sam_sam_sam View Post
I hope that when you this type of testing that you do a complete write up about how you did it
Will do for sure.
There's still a lot of things about it that I'm experimenting with, though. So perhaps when I get a solid method (and setup) of doing everything the same way every time, that's when I will post it. Right now, I'm still doing everything with a ton of jumper wires/clips and it just looks like a bird's nest, lol.
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Old 09-16-2021, 12:25 PM   #11
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

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higher ratings on all the outputs..."[/I]
35a on the 5v rail... Deer/L&C anyone?
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Old 09-17-2021, 01:07 PM   #12
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Default Re: Casing Power MPT-301 [PCB ATX9806b-p REV: A3] - load testing

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Originally Posted by momaka View Post
Hmmm, just stumbled upon this after trying to catch a few details of my recap...

So, the Q-TEK ADT-350 in the last link above - that's not actually a PSU made by Macron. It's a CWT ISO series, and probably one of their most gutless ones. See this thread on the CyberLink CWT-320ATX:
https://www.badcaps.net/forum/showthread.php?t=39222
The fun part if it was not obvious was that these two PSU's had the same manufacturer on the type rating plate, and the worse one was rated higher!
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