Troubleshooting Old Chiefmax 650Watt ATX Switching Power Supply

[Zippie]

I’m looking for some advice troubleshooting an old Chiefmax 650w power supply in a PC, if it’s advisable to dig into it.

Worst case I can replace the PSU, I’m just interested in learning the troubleshooting process. However, it’s out of my area of expertise and I could use some direction.

During PC operation I heard a loud pop noise, like a cap gun and the tower lost power.

Initially there is no power output 3.3v, 5v, or 12v when jumping the power on pin to ground. Also, no fan power.

Opening the PSU the only things visible initially are what appears to be solder blown off the center pin of 2 transistors KS13009 on the back of the board, and some brown discoloration as evidence of excessive heat on a rectifier MOSFET U20C20C on the other heat sink. See pics.

My plan is to remove the heat sinks to check them off the board. I wanted to check and see if there is any other diagnostics I can do as far as tracing power through the board before I do that. Is this typically the problem or just a symptom of another issue?

Thanks.

System:
First Generation HP Envy Motherboard ANGELICA 1.2
FX8350 Processor with DeepCool cooler
16Gb Nemix RAM DDR3 12800 UDIMM
MSI 1060 GPU
High airflow case
Chiefmax 650w PSU

[stj]

300-350w generic psu,
check the fuse and black thermister in front of it - it looks split.

nice setup btw - AMD JackHammer - same as one of mine

[Zippie]

Thinking it over, I’m pretty sure it over heated from lack of airflow, a heavy pile of dust under case at intake fan.

Fuse was fine until I shorted the pcb to the case…😕 Will have to get that sorted out before I can do anything else.
Thermister had some dust on it that wiped off. Seems intact visually.
I think I may get a fuse holder and add to the board.
Honestly if you think it’s only good for 300-350w realistically I may be better replacing it.
I know it’s cheap for a 650w claim, but I’d rather be closer to 450w min for peace of mind with the FX8350 and 1060.
I may consider 1 more small GPU upgrade, but I’m about at max with what I think this rig will do. It’s been through a lot in 14 yrs.
Just wanna keep it going for sentimental reasons.
Thinking of retiring it to a retro pi arcade emulator and making a stand up cabinet to toss it in. That would be an easy breathing end of life for it.
Thanks for the advice. I’ll get back when I find out more.

[stj]

the cpu is about 120w
i dont know what the gpu needs.

it's 100% an old 350w psu,
infact it has hardly any output caps and no input filters!

if your shopping for a new psu - dont buy any with a 110/20 input switch, it's a sign of an ancient design
get one with a universal 100-250v input

[Zippie]

Ok. I’ll look into that. More than likely buying a new one. Found an old one I replaced that was still working to test it.

VENUS ATX-450W

I replaced it for powering off randomly. Later discovered it was the cpu over heating which lead to the deep cool cooler, and the high air flow case. After those upgrades it hasn’t shutdown unexpectedly. I reasoned the VENUS PSU was not the problem.

That being said the VENUS lasted about 3 min and I got a fireworks show. Now I have 2 toasted power supplies and some diagnosis to do.

I’ll post the results of the second 4th of July experience when I get back into it.

Thanks for all the help.

[Zippie]

I’m starting to wonder if the PSU overheated and shorted something in the board or the other way around.

The second power supply did fine before with no problem. I did upgrade GPU in the mean time. As well as a bigger CPU and much bigger CPU fans and 4 additional case fans in the new setup. I guess there is quite a bit more draw that I haven’t calculated. However I did think 450w was sufficient when I did the math when the GPU was upgraded.

2 things I guess I need to decide moving forward.

1) Is it reasonable or worth it to try a rebuild/beef up of one of the power supplies?
(Just learning experience at this point)

2) What's the best way to go about troubleshooting the possibility of something wrong with the motherboard?

Im obviously in over my head, but I’ve got nothing to lose if it doesn’t get real expensive.

I do have access to a handful of electrical components given to me that were purchased at auction from a local tech school that closed down. May post about that in another thread.
Mostly caps, diodes, and resistors. Some trim pots and various random things.

If it’d be better advised to get a better PSU and motherboard I do have that option. Just about to start getting into more money than it would cost to build a much superior later era system.

I’ve attached pics of the following:

The original 650 chiefmax

The 450 replacement Venus

The factory original 300w HP PSU
(obviously too small and not compatible as far as output connections at this point. It does seem to have much more input and output components on the pcb.)

Thanks again.

[stj]

lets see inside the Venus.

[dmill89]

lets see inside the Venus.

^This, I built a similar system years ago (and FX8320 and GTX1060) and it ran just fine with a 400W PC Power & Cooling Silencer MKIII (re-branded Seasonic S12II), so a "real" 450W unit would be fine, but many "no name" units (and some "major brands" as well) don't come anywhere near their rated capacity.

I.E. This "500W" SolidGear unit I looked at a few years ago that could barely handle 300W before dying (and being way out of spec on ripple well before that):https://www.badcaps.net/forum/troubl...e2#post1440496

[Zippie]

My apologies. I meant to post the pics of the 3 I described.
1-chiefmax
2-venus
3-HP

[dmill89]

My apologies. I meant to post the pics of the 3 I described.
1-chiefmax
2-venus
3-HP

Both the Chiefmax and Venus look like 300-350W units at best in reality (based primarily on the size of the transformer and primary caps hard to say 100% without knowing the specific components i.e. switching transistors/mosfets, bridge rectifiers, secondary rectifiers, etc.), and not much if any improvement over the original HP unit (and probably less efficient).

If you're in the US as you profile shows, if you're looking for a budget unit, you may want to look at something like this: https://www.amazon.com/Thermaltake-C...d=1161760&th=1
It certainly isn't the best quality PSU in the world (and has second-tier caps like most "budget" units) but can actually deliver its rated power and is a much better built unit with a much more modern design than those "no name" units.

If cost is less of an object Seasonic, and the higher-end (80+ gold and above) EVGA and Corsair would generally be my recommendations (there are of course other good options as well).

[Zippie]

Thanks. After talking with some PC builders at work I’m pretty sure I’ll get a gold or better rated unit.

Is there any checks I can do to the motherboard before I put it back together to verify if it’s sound or in danger of taking out the next PSU?

Or do I just cross my fingers and hope for
the best.

The chiefmax ran this rig for over 6
mos. without any trouble. I do believe cooling was compromised in the way of air restriction more than likely, but I’m concerned something on the board may be damaged at this point.

[dmill89]

Thanks. After talking with some PC builders at work I’m pretty sure I’ll get a gold or better rated unit.

Is there any checks I can do to the motherboard before I put it back together to verify if it’s sound or in danger of taking out the next PSU?

Or do I just cross my fingers and hope for
the best.

The chiefmax ran this rig for over 6
mos. without any trouble. I do believe cooling was compromised in the way of air restriction more than likely, but I’m concerned something on the board may be damaged at this point.

On any decent PSU any short/fault should trip the protection circuitry and cause it to power off immediately. If you just want something to test the board with, as long as it still works the original HP unit should be enough to at least power it up and see if it will boot, just POSTing and booting to the desktop won't generally put the components under much of a load (major OEM units also generally have at least somewhat decent protection circuitry as well).

[Zippie]

Ok. Thanks. I appreciate the help. I have enough basic knowledge to get myself in trouble sometimes. Most of the lingo on this forum is Greek to me. I’ll get a decent PSU and see how it goes.

[momaka]

I'm looking for some advice troubleshooting an old Chiefmax 650w power supply in a PC, if it's advisable to dig into it.

Worst case I can replace the PSU, I'm just interested in learning the troubleshooting process.

If it's just for learning purposes, then go ahead and dig in. Otherwise, it's not that great of a PSU and hence why it blew up, but I'll cover that in more detail below.

During PC operation I heard a loud pop noise, like a cap gun and the tower lost power.

Initially there is no power output 3.3v, 5v, or 12v when jumping the power on pin to ground. Also, no fan power.

Opening the PSU the only things visible initially are what appears to be solder blown off the center pin of 2 transistors KS13009 on the back of the board, and some brown discoloration as evidence of excessive heat on a rectifier MOSFET U20C20C on the other heat sink. See pics.

KS13009 are you main switching transistors (NPN type BJT's) - i.e. what makes power come to the 3.3V, 5V, 12V, and -12V rails. It's typical for these transistors to blow up in cheap power supplies either because the transistors are of questionable quality, an output rectifier shorted (it seems that some shoddy half-bridge topology PSUs cannot deal well with shorted output rectifiers), or MOST OFTEN the PSU was waaaaay too overrated and in reality could never do the Watts promised on the label.

As for the 5VSB, that should be on its own separate circuit and should still be functional if the main fuse and NTC thermistor are not blown open-circuit yet.

To troubleshoot the PSU, start by removing the two KS13009 BJTs and all small parts that are connected to their pins. Very likely you will find a pair of blown (open) low-resistance resistors, shorted diodes, and possibly more. See how I went about it in this thread here:
https://www.badcaps.net/forum/troubl...pcb-wf-c-rev-e
(Note: it's a bit lengthy in discussion, but should also hopefully familiarize you a bit more with PSUs and their components.)

You will also want to remove and check the U20c20c rectifier. I suspect this is the 12V rectifier of your PSU... which means the PSU was never really capable of more than 20 Amps on the 12V rail - i.e. 240 Watts. So the numbers on the label claiming the 12V rail can do 34 Amps is a complete lie.

Your FX8350 CPU and GTX 1060 GPU very likely regularly pushed the power consumption on the 12V rail past 240 Watts at full tilt/load. Now, most rectifiers can take quite the abuse... but they can also only do it for so long and so much. I suspect you will find your U20c20c rectifier also shorted. Of course, remove it from the PSU to confirm. If one or both outer pins read short-circuit or very low resistance (below 100 Ohms) on your multimeter, then it's bad.

VENUS...

The moment I saw that name, I cringed and knew what I was about to read.
No surprise that one blew too. Venus PSUs, from what I remember people posting pictures here, were pretty garbage too. Yours doesn't actually appear to be *that* bad... but it's still a 200-250W *real power* generic POS PSU.

I'm starting to wonder if the PSU overheated and shorted something in the board or the other way around.

Most certainly the issue is with these cheap power supplies and not the motherboard / CPU / GPU. If the CPU or GPU were bad, a good quality PSU would shut down and not go bad when it detects a problem. With cheap PSUs, it's a bit of a coin toss as to whether or not they shut down properly... but usually, they do shut down. Drawing more power from these cheap PSU than what they can handle is what almost always gets them to blow up, mostly because they don't have over-current protection and their over-power protection is set either too high or not working properly.

The second power supply did fine before with no problem. I did upgrade GPU in the mean time. As well as a bigger CPU and much bigger CPU fans and 4 additional case fans in the new setup. I guess there is quite a bit more draw that I haven't calculated. However I did think 450w was sufficient when I did the math when the GPU was upgraded.

A good quality 450W PSU should indeed be fine for that system. In fact, even a 300 Watt PSU can do the job, again provided it's a high-quality unit that can do its full 300 Watts on the 12V rail (what modern systems need.)

1) Is it reasonable or worth it to try a rebuild/beef up of one of the power supplies?
(Just learning experience at this point)

If you enjoy soldering and want to get learning experience in electronics repair, then it is worth to do.
However, even if you do fix any or both of these PSUs, I wouldn't suggest to use them on such a system with such high power draw. You can try to "beef them up", but IME you can never get too far on these cheap PSUs. They cut costs in every corner (or is it, they cut corners at any cost? ) So upgrading them to become a high-power unit is not possible. They are and always will remain 200-300 Watt PSUs. However, at least when you replace/upgrade the output caps and other parts, they can become a little more dependable (maybe even relatively respectable) 200-300 Watt PSUs. I do run a few PSUs like that in low-power PCs (CPU + onboard graphics or very low-power GPU), and they do fine there.

My apologies. I meant to post the pics of the 3 I described.
1-chiefmax
2-venus
3-HP

Between these three, I have to say the 300W HP / Bestec is clearly the winner here. It has all input filter parts installed and CAN actually do the rated output on its label - something that neither the Venus nor the Chieftec can ever do. Looks like it needs just new caps on the output and the 3.3V rail toroid replaced (something that can be "borrowed" from either the Venus or the Chiefmax PSU ). Maybe the 3.3V rail mag-amp transistor checked too. But all in all, looks like a salvageable unit. And it has good & functional protections, unlike the Venus and Chiefmax.

That being said, I don't know which one to put at 2nd place. Both the Venus and the Chiefmax are about on par. The Venus PCB looks a little more promising, since it has space for two output caps on each major rail, which will greatly help with lowering output ripple and noise (especially at higher loads.) It also has a complete input EMI/RFI filter. But it has a smaller transformer (with a fake "35" size label), so it's really a 200-250W max PSU (probably closer to 200W to be on the safe side.) With bigger and better caps on the output though (after it's fixed), it should be an -OK- 200 Watt PSU.
Meanwhile, the Chiefmax appears to have better/bigger heatsinks and bigger main transformer, so it may be able to handle slightly more power. However, the fact that there is only ONE cap on each output rail is very concerning. Very likely, it won't be able to keep the ripple & noise in spec above 150-200 Watts load, if even that much. Perhaps if you really over-size the output caps (i.e. install 3300/3900/4700 uF or higher capacitance parts) then it might have a better chance of providing cleaner power. It's also missing the input EMI/RFI filter components, so you would have to add those too. On that note, the little blue "safety" caps in the lower-left corner are regular 1 or 2 kV ceramics and not proper safety Y2-class caps. This is a no-pass for safety regulators. They need to be removed and replaced with proper Y2-safety caps.

Or do I just cross my fingers and hope for
the best.

That's really the only option here, unfortunately.
The cheapo Venus and Chiefmax PSUs could have damaged something in the system at this point. But if you get a good quality name-brand PSU, it won't get damaged and will gracefully shut down if it discovers a fault.
I suspect you will find the PC is still OK, though. Despite the fireworks show these cheap PSUs put on, they don't damage the hardware all that often.

[stj]

any pc psu is worth fixing - you dont have to use them for pc's
i use old 200-300w psu's for everything from running a 12v tyre compressor in the house to just testing stuff that wants 5v or 12v

[momaka]

I'm with you on that one, stj, I also use a lot of crappy/gutless/old PSUs for various kinds of tasks.
When it comes to the truly gutless PSUs, let's put it this way: brushed DC motors don't care about noise, EMI, or ripple current.

[Zippie]

Thanks Momaka!
Very helpful.
I’ll check the link when I have some time.
Really appreciate the feedback here.