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Old 03-27-2021, 12:46 PM   #41
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Default Re: 1300W PSU - Help with replacement mosfet

72w sounds like a halogen capsule hybrid.
it probably cant pass enough current for the pfc circuit to start - do you have anything big - like 150w?
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Old 03-27-2021, 02:21 PM   #42
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Default Re: 1300W PSU - Help with replacement mosfet

Verified i have 3V on ps_on pin
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Old 03-27-2021, 02:23 PM   #43
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Default Re: 1300W PSU - Help with replacement mosfet

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72w sounds like a halogen capsule hybrid.
it probably cant pass enough current for the pfc circuit to start - do you have anything big - like 150w?
Unfortunately that the only bulb i have in the house. its a new house to everything is LED.
I guess ill go out to lowes and pick up some high watt bulbs
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Old 03-27-2021, 03:15 PM   #44
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Default Re: 1300W PSU - Help with replacement mosfet

tried a 150W bulb.
same result.
Bulb didnt even light up though.
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Old 03-27-2021, 08:11 PM   #45
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Default Re: 1300W PSU - Help with replacement mosfet

Got a sandwich press or toaster oven with mechanical switches? A toaster would do as well, if you can figure a way to hold down its slider so that it's turned On all the time. Basically, look for an appliance with a heating element in the range of 500-800 Watts, more or less. With that wired in place of the incandescent bulb, the PSU APFC circuit shouldn't have any problems turning On. However, I do advise that you also keep the light bulb wired in parallel to whatever appliance you end up using, so that you would still have a visual indicator if something in the PSU shorts.

You may also need to put some kind of a load on the PSU output as well, since this is a high-power PSU. Perhaps a system that draws less than 60 Watts (like a low-end i3, or a Pentium III or early Duron board.) Or, you could also use several incandescent car headlight/tailight bulbs (12V) if you have any, connected to the 12V rail.

If the PSU still refuses to turn on, check if the PWM/APFC chip on the primary side is getting power on its VCC pin when you short PS_ON to ground. If not, start tracing back and find the transistor and optocoupler connected to the VCC pin of the PWM/APFC controller. You should also check that the primary-side auxiliary supply (generated from the 5VSB circuit, but on the primary side) is up to proper voltage. For these voltage checks, make sure you use the negative lead of the big cap on the primary side as your ground (and be careful, since this is the HOT side - i.e. not isolated from mains, thus potentially dangerous if you touch something with your hands.)

And we really need more pictures of the PSU. I know the thing is packed and hard to see anything in it, but I'm really troubleshooting in the dark here.

Last edited by momaka; 03-27-2021 at 08:16 PM..
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Old 03-28-2021, 05:34 PM   #46
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Default Re: 1300W PSU - Help with replacement mosfet

meh so after swapping to the 150W something weird happen. im certain i didnt short anything by accident but now im only getting .4V on my mains.
at the point of when i noticed i was probing and around the ps-on chip there. labeled GR8313 8pin dip in the corner there.
no shorts found yet

heres some pics.
Attached Images
File Type: jpg image0.jpg (316.8 KB, 25 views)
File Type: jpg image1.jpg (333.5 KB, 22 views)
File Type: jpg image2.jpg (337.3 KB, 21 views)
File Type: jpg image3.jpg (295.5 KB, 20 views)
File Type: jpg image4.jpg (473.3 KB, 22 views)
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Old 03-28-2021, 07:48 PM   #47
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Default Re: 1300W PSU - Help with replacement mosfet


well you need some new opto-isolators!!
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Old 04-01-2021, 11:28 AM   #48
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Default Re: 1300W PSU - Help with replacement mosfet

stj, that could be just a picture artifact or conformal coating.
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Old 04-06-2021, 12:13 AM   #49
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Default Re: 1300W PSU - Help with replacement mosfet

Quote:
Originally Posted by sdinelli View Post
meh so after swapping to the 150W something weird happen. im certain i didnt short anything by accident but now im only getting .4V on my mains.
Mains?
As in, AC-side on the primary before bridge rectifier or DC-side on the primary after the bridge rectifier... and by that, check the voltage both right at the bridge rectifier and across the main caps. You should have about 160V DC on either (for 120V mains.) If not, check fuse again, as well as NTC thermistor (located between APFC coil and the 1st primary-side 400V cap.)

Once you have confirmed you have about 160V DC on these parts, check 5VSB again. Better yet, my suggestion is to plug in a small 12V light bulb on the 5VSB output, so that way you can get a visual that the 5VSB is working. This will come handy when testing the PSU - particularly when you short PS-ON to ground. When you do that, and regardless of whether the PSU turns ON or not, is the bulb hooked to the 5VSB output continuing to glow? The idea is to be able to verify that the 5VSB is running at all times as long as the PSU is plugged in. Then we can go troubleshooting further. Please report back what happens with the following tests/suggestion I made above.

Quote:
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stj, that could be just a picture artifact or conformal coating.
Maybe artifact / reflection from flash/light, but I don't think this PSU has conformal coating. So O/P should indeed check what's the deal with those optocouplers - any sign of bubbling, bulging, or discoloration on them should get them removed from the board and checked.
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Old 04-06-2021, 07:27 PM   #50
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Default Re: 1300W PSU - Help with replacement mosfet

Alright, good news!!! I'm a dumb ass lol i must have somehow flipped the main switch last time i took measurements and i guess that .4V was just residual and the psu was just off.

OK recap
Just to note, im only getting 113VAC out of my plug after the bulb.
I am getting 150V across the main caps.
I am getting 5VSB with ps-on open and shorted.
I am getting 3V on my ps-on which shorts to 0.

I have a psu tester that shows LEDs of the voltages if theyre present.

I have no idea what an octocoupler is! i thought he was making a joke when he said that

Please advise next step of troubleshooting.
I'm ready to tear into her again.


Quote:
Originally Posted by momaka View Post
Mains?
As in, AC-side on the primary before bridge rectifier or DC-side on the primary after the bridge rectifier... and by that, check the voltage both right at the bridge rectifier and across the main caps. You should have about 160V DC on either (for 120V mains.) If not, check fuse again, as well as NTC thermistor (located between APFC coil and the 1st primary-side 400V cap.)

Once you have confirmed you have about 160V DC on these parts, check 5VSB again. Better yet, my suggestion is to plug in a small 12V light bulb on the 5VSB output, so that way you can get a visual that the 5VSB is working. This will come handy when testing the PSU - particularly when you short PS-ON to ground. When you do that, and regardless of whether the PSU turns ON or not, is the bulb hooked to the 5VSB output continuing to glow? The idea is to be able to verify that the 5VSB is running at all times as long as the PSU is plugged in. Then we can go troubleshooting further. Please report back what happens with the following tests/suggestion I made above.


Maybe artifact / reflection from flash/light, but I don't think this PSU has conformal coating. So O/P should indeed check what's the deal with those optocouplers - any sign of bubbling, bulging, or discoloration on them should get them removed from the board and checked.
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Old 04-07-2021, 10:57 AM   #51
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Default Re: 1300W PSU - Help with replacement mosfet

Look at IC102 and IC506 about in the middle of this picture here:
https://www.badcaps.net/forum/attach...3&d=1616974045
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Old 04-08-2021, 07:36 PM   #52
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Default Re: 1300W PSU - Help with replacement mosfet

not sure how to measure them but the measure open from one side to the other

Quote:
Originally Posted by Per Hansson View Post
Look at IC102 and IC506 about in the middle of this picture here:
https://www.badcaps.net/forum/attach...3&d=1616974045
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Old 04-08-2021, 09:02 PM   #53
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Default Re: 1300W PSU - Help with replacement mosfet

The optocouplers have numbers on them, get the datasheet and you will see how they work and how to check them. They are basically a led on one side and a photo transistor on the other, when the led lights, the photo transistor conducts.

Last edited by R_J; 04-08-2021 at 09:06 PM..
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Old 04-08-2021, 10:34 PM   #54
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Default Re: 1300W PSU - Help with replacement mosfet

Quote:
Originally Posted by sdinelli View Post
not sure how to measure them but the measure open from one side to the other
Like R_J noted above, they should appear like a diode on one side (the side that is connected to the secondary of the PSU) and open on the other (unless current is flowing through the diode side, which will make the photo-transistor side begin to conduct.)

PC817 tends to be a very common part used for optocouplers in PSUs, though you may have something else, so check what you have.

Best way to test is out of circuit and with power applied. Something like a 5V power adapter and 470-1000 Ohm resistor in series with the diode/LED diode side should be enough to "turn ON" the photo-transistor side. Thus, measure resistance (or voltage drop / continuity) on the photo-transistor side when the diode/LED side has power going to it and when it doesn't. You should see that resistance / voltage drop change (become lower) when power is applied.

Last edited by momaka; 04-08-2021 at 10:36 PM..
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Old 04-09-2021, 04:08 PM   #55
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Default Re: 1300W PSU - Help with replacement mosfet

OK thanks, ill play around.
What purpose in the circuit do these have?


Quote:
Originally Posted by momaka View Post
Like R_J noted above, they should appear like a diode on one side (the side that is connected to the secondary of the PSU) and open on the other (unless current is flowing through the diode side, which will make the photo-transistor side begin to conduct.)

PC817 tends to be a very common part used for optocouplers in PSUs, though you may have something else, so check what you have.

Best way to test is out of circuit and with power applied. Something like a 5V power adapter and 470-1000 Ohm resistor in series with the diode/LED diode side should be enough to "turn ON" the photo-transistor side. Thus, measure resistance (or voltage drop / continuity) on the photo-transistor side when the diode/LED side has power going to it and when it doesn't. You should see that resistance / voltage drop change (become lower) when power is applied.
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Old 04-09-2021, 08:49 PM   #56
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Default Re: 1300W PSU - Help with replacement mosfet

Quote:
Originally Posted by sdinelli View Post
What purpose in the circuit do these have?
One is for enabling power to the PWM chip on the primary side when you short the PS-ON signal to ground (so the main PS can start.) The other is for sending feedback from the secondary side (from the supervisor chip) to the primary side (PWM IC) to tell it if it needs to "work harder" or "work less", depending on the load and output voltages on the secondary side.

So the typical operation is as follows:

0) Before PS-ON is shorted to ground, the 5VSB circuit is working and providing both standby (5V) to the supervisor chip on the secondary side and also generating an auxiliary power rail on the primary side (both for itself and the PWM IC, when needed.)

1) When PS-On is shorted to ground, the supervisor chip (secondary side) sends a signal through the power-enabling optocoupler and turns On a small transistor that lets power flow from the auxiliary power rail (generated by the 5VSB circuit on the primary side) to the PWM IC on the primary side.

2) PWM IC(s) (there may be one or two, depending if there is an APFC circuit - which your PSU has - and depending if the APFC circuit is controlled from the same PWM IC as the main PS or from a separate chip... hence possibility of two chips) starts working and first brings up the APFC voltage up to normal operating levels (typically 375-395V). Then... or if no APFC circuit present, the PWM IC will start switching the transistor(s) for the main PS.

3) As transistor(s) on the primary are switched On-Off, this produces pulses through the transformer and voltages come up on the secondary side. The supervisor IC on the secondary monitors the voltages and sends a signal through the feedback optocoupler to limit the switching pulses once the voltage are up to normal operating values... and continues to do so constantly, or until PS-ON signal is de-asserted/removed.

4) When PS-ON signal is de-asserted (turning the PC off or putting it on Standby/Suspend/Sleep), supervisor IC turns off the signal going to the power-enabling optocoupler, and this stops the PWM IC operation, which brings the main PS to the Off state.

Last edited by momaka; 04-09-2021 at 08:53 PM..
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Old 04-09-2021, 09:18 PM   #57
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Default Re: 1300W PSU - Help with replacement mosfet

Quote:
Originally Posted by momaka View Post
One is for enabling power to the PWM chip on the primary side when you short the PS-ON signal to ground (so the main PS can start.) The other is for sending feedback from the secondary side (from the supervisor chip) to the primary side (PWM IC) to tell it if it needs to "work harder" or "work less", depending on the load and output voltages on the secondary side.

So the typical operation is as follows:

0) Before PS-ON is shorted to ground, the 5VSB circuit is working and providing both standby (5V) to the supervisor chip on the secondary side and also generating an auxiliary power rail on the primary side (both for itself and the PWM IC, when needed.)

1) When PS-On is shorted to ground, the supervisor chip (secondary side) sends a signal through the power-enabling optocoupler and turns On a small transistor that lets power flow from the auxiliary power rail (generated by the 5VSB circuit on the primary side) to the PWM IC on the primary side.

2) PWM IC(s) (there may be one or two, depending if there is an APFC circuit - which your PSU has - and depending if the APFC circuit is controlled from the same PWM IC as the main PS or from a separate chip... hence possibility of two chips) starts working and first brings up the APFC voltage up to normal operating levels (typically 375-395V). Then... or if no APFC circuit present, the PWM IC will start switching the transistor(s) for the main PS.

3) As transistor(s) on the primary are switched On-Off, this produces pulses through the transformer and voltages come up on the secondary side. The supervisor IC on the secondary monitors the voltages and sends a signal through the feedback optocoupler to limit the switching pulses once the voltage are up to normal operating values... and continues to do so constantly, or until PS-ON signal is de-asserted/removed.

4) When PS-ON signal is de-asserted (turning the PC off or putting it on Standby/Suspend/Sleep), supervisor IC turns off the signal going to the power-enabling optocoupler, and this stops the PWM IC operation, which brings the main PS to the Off state.
Very nicely explained, thank you.
Im learning a lot and i hope i can get this working. I appreciate everyone's help
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Old 04-20-2021, 07:32 PM   #58
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Default Re: 1300W PSU - Help with replacement mosfet

alright so update:

since i have two of the same PSU with the same problem, i decided to install the new parts in the second one just to make sure i didnt F anything up on the first one with my initial troubleshooting.
the Second one has the same results as the first.
So i guess i have to do more testing...

on the other hand i ALSO had an 1800W psu which had a single mosfet config and i found it shorted with nothing else wrong.
i used one of the good mosfets from the other bad PSU's and put a new fuse in and it works!
when i tested initially, i used one 150W bulb and it started flashing, then ran the 150 in parallel with the 72W and it still flashed but it was almost enough juice that my tester actually showed all the voltages so i tested it with out the current limiter and it works however i havnt put much load on it just a 12V fan
my first successful PSU repair. Sorry, no pictures
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Old 04-24-2021, 10:11 PM   #59
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Default Re: 1300W PSU - Help with replacement mosfet

Quote:
Originally Posted by sdinelli View Post
alright so update:

since i have two of the same PSU with the same problem, i decided to install the new parts in the second one just to make sure i didnt F anything up on the first one with my initial troubleshooting.
the Second one has the same results as the first.
So i guess i have to do more testing...
If the PSUs have both the same symptoms, then they both must have the same exact issue / component(s) bad.

Quote:
Originally Posted by sdinelli View Post
on the other hand i ALSO had an 1800W psu which had a single mosfet config and i found it shorted with nothing else wrong.
i used one of the good mosfets from the other bad PSU's and put a new fuse in and it works!
when i tested initially, i used one 150W bulb and it started flashing, then ran the 150 in parallel with the 72W and it still flashed but it was almost enough juice that my tester actually showed all the voltages so i tested it with out the current limiter and it works however i havnt put much load on it just a 12V fan
my first successful PSU repair. Sorry, no pictures
Nice Congrats!
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