Hi i was given a PC which supposedly had bad mobo but turned out its the PSU. its HP-D3057F3H PSU and it wont turn on when connected to mobo but turns on when i short the green and black wire. then i saw the 5vsb is only 2v when connected to mobo and 5v when not connected. could this just be a bad cap in PSU? when i opened it up there was swollen cap its a 10v 2200uf Ltec but i dont know if that for the 5vsb
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Last edited by nubinator; 01-15-2012, 10:22 PM. -
Re: HP-D3057F3H low 5vsb
I wouldn't usually expect a cap that big on the 5VSB but I suppose it is possible. A bad cap could definitely cause the rail to go low like that, I've seen it multiple times. There is the possibility that other caps are bad besides the one that is swollen, caps don't always show visible signs of failure. If you do repair it I would recommend replacing all the caps from questionable brands (in that PSU probably every cap or almost every cap, since HiPro tends to use lower end caps). That being said since it is a 300w HiPro and is standard ATX you may just want to replace the PSU unless you want a hobby project since it is only a mediocre brand and a suitable replacement can be had for less than $35.Last edited by dmill89; 01-15-2012, 10:54 PM. -
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Re: HP-D3057F3H low 5vsb
well got out esr meter i never use and it picked a couple of teapo caps 1000uf 6.3v and 1000uf 10v as bad also so will replace them see how it goes.Comment
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Re: HP-D3057F3H low 5vsb
1000uf caps are extremely common on the 5vsb rail so it is likely one of those is the culprit. As retiredcaps stated a 2200uf is used on the 5vsb in some designs, however such a large cap on a 2-3 amp rail is not very common. Although if the cap is visibly failed it still needs replaced regardless of what rail it is on since it will only lead to problems later.Comment
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Re: HP-D3057F3H low 5vsb
It could still be something wrong with the motherboard, loading down the 5vSB so much that it ends up at 2v, unless you already tried a new PSU and found the board to work."Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHornComment
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My Hipro HP-D3057F3H only had 2.6V on the 5VSB
The fault was due to 5ohm ESR on one of the non-bulged Teapo SC 1000uf output caps; so i guess that the Viper22A detects overcurrent, and goes into a low power mode
BTW, this PSU has a tricky (for me), unusual, feedback circuitry on the 5VSB: The Viper22A is connected to the first optocoupler, of which the secondary side is earthed, and which is turned off or on by one of the TL431 shunt regulators (there's three on the secondary side of this PCB), which is connected to the adjacent optocoupler.
Also, in terms of being able to remove the board from the case, this is a technician-friendly PSULast edited by socketa; 07-30-2024, 04:48 PM.Comment
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So I have a cheap non working ATX PSU that I was learning to repair a decade ago. At the time, it blew the main fuse, bridger rectifier, NTC, and primary 9A 900V MOSFET. Replaced all except the MOSFET. 5VSB came back online. Then I poked around in it so much, measuring components one by one to a point I accidentally made the 5VSB circuit primary side went bang. Blown the AP8022 (Viper22A) PWM chip, along with a low resistance resistor and the PC817 opto isolator. I replaced them all.
In the process of poking around, I also lost a zener diode that stabilize the voltage coming from... -
Hi,
Finally replaced all of the shorted 4148's and resistors and an blown tl431 on my FSP300-60GTF after 5VSB going crazy and destroying it self. Those components also made the secondary transistors appear shorted (while in reality they weren't).
Powered it on through my dim bulb tester and they (bulbs) only flash once meaning primary caps are getting charged, but that's it. No 5VSB, PS_ON voltages.
I am sure I have replaced the components correctly and that there weren't any shorted/blown traces left.
Any ideas where to go next? -
so i took out one of my spare gigabyte ep35-ds3r mobos from storage for use to do some cpu, ram and video card testing of stuff i bought from ebay and got for free from momaka. he bought 50 e8400 cpus for cheap from ebay some years ago and i decided to help him relieve him of some of his supply since he had waaaay too many!!
what did we say about hoarding too much stuff and depriving others of them?! *cough* socialism *cough* lol! 
i had to blow some dust off the board and heatsinks with the datavac as i didnt clean it up before putting it in storage. after finishing... -
Ok so this doing my head in and hopefully someone more knowledgeable will be able to assist.
I've got a MacBook Pro 820-2915-A it will power on without the battery connected, but when the battery is connected it will do a 2,3-second fan spin when pressing the power button and then nothing.
After measuring and probing around I found that R7051 was bad, reading high instead of 2.2Ω so I replaced it. Still the same issue, I have the green light on the charger but it won't power on or charge the battery.
So to cut the long story short I've replaced U7000,... -
This was a no power initially. Thanks to your help, I discovered it was the first mosfet, so I replaced. Now, the device will power up only if the battery is NOT connected. As soon as I connect the battery, it shuts off. If I connected the battery while the device is off, it simply will not respond to the power button. I replaced the battery, and while I suppose the new battery could be faulty, I'm assuming it is not. I'm having the same behavior with the new battery. I measure .2v at the charging coil. Manually applying power to the + and - at the battery header, there is no charging happening....
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