Question about Intel (ATX350P4) 350-Watt Power Supply

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Leaking of transistors

When i turned on the computer i was shocked because of the spark from my 350watts power supply then i did'nt hesitate to open it to see what kind of ic is been damage and i found 2 ic's that are leaking... what will i do?? buy new 1 or try to repair? if i repair can u give me an ic. for replacement?

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Re: leaking of transistors

No. not only is it cheaper in the end to buy a new supply, but there are most likely more parts (which may be hard to locate without special equipment) nuked than only the transistors. so buy a new one.

Posted on Nov 15, 2007

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My enermax power pack sparked out of the fan in the back and now my computer wont turn on. Not sure if it's the power pack or the board is fried... Any help would be appreciated thanks =)

if it sparked then something inside the power supply malfunctioned and that is the reason it wont work. You will need to replace it. Unlikely that it fried your board in the process. You can test this by swapping the power supply with one that you know works.

May 20, 2010 | Enermax EG301P-VB (eg301vb) Power Supply

2 Answers

Blown fuse everytime it powers on

yes right there is a short circuit in power supply if you are non technical then replace the power supply if you are technical then open the power supply and check the 4diodes of bridge if faulty replace it again check transistor attatched to heat sink if faulty repalce it

Feb 28, 2010 | Pyramid (PS36KX) 600-Watt Power Supply

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I would also have liked to have had a schematic diagram for my ECHOSTAR 450w ATX power supply.

Not having one though, I have replaced two capacitors (one with a bulging top) and another with a leaking top, three rectifiers (two shorted and the third had a cracked case), and have ordered transistor Q1 (also shorted). Will also need to repair trace damage on the bottom of the circuit board. Other components check out OK so I hope it will be working again after the transistor arrives Monday. I need the -5v this one supplies to get my old computer running so I can retrieve last year's tax info.

Jan 17, 2010 | Echo Star 450W 450 Watts ATX Power Supply,...

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PC turns on...but no display. Monitor and cable

I fully agree with you.

Capacitors have gone bad in the power supply. This causes a weak power rail.

Enough power to spin fans, and light- lights, but not enough power to turn on the Processor. (Harddrive is inactive because there is no processor running)

Power supply's are rated in Watts. (Volts x Amperes = Watts)

1.ALL the lights use less than 1 Watt.
2.EACH fan uses 2 to 3 Watts.

A typical Processor uses 55 to 125 Watts!
Depends on the processor.

BIOS won't turn the processor on, and hand the computer over to the Operating System, (Example: Windows XP), because there isn't enough power.


I DO NOT advise opening a personal computer power supply!
Those Electrolytic Capacitors I have referred to, hold a charge for WEEKS, sometimes MONTHS, after the power is disconnected to the power supply.

Capacitors are made to slowly build up a charge, then release it all at once!

If someone touches across the terminals of a capacitor, and it's still good, it can release it's charge to them!
If someone touches a circuit that capacitor/s are in, the charge can be released to them!

Shock can range from BAD to FATAL!

It is for this reason that the best, and most effective method, is to replace the power supply with a known, good one for a test.

I realize power supply's do not grow on trees, and not everyone is a computer geek like me, and has several laying around, (I mean Tech, lol!)

IF you are stating this question referring to an eMachines that uses a Bestec ATX style, 300 Watt power supply, the cost is very inexpensive for a new one.

Not to slam a company, but Bestec PSU's are cheaply built, and this is the reason it failed. (IF yours is a Bestec)

You don't have to break the bank however, to replace this power supply with one that is much better.

An ATX style of power supply is a very common one. Approximately 85 to 90 percent of personal computers use this style of power supply.

This example would get you buy for quite sometime, (IF you keep the inside of the computer clean regularly, and the power supply, with a can of compressed air for computers. 75 percent of failed computers that come to my shop are dirty inside)

Just an example. Not advertising for the power supply manufacturer, not the website.

Have any additional questions I'm right here.

Nov 10, 2009 | E-Machines Bestec ATX-300-12E Rev. D 300w...

3 Answers

Ultra 350 Power supply very loud fan

It's not normal for the fan to be loud, what makes them loud is either a build up of dust on the fan blades or the bearings are going on the fan itself.
If the PSU is working fine then you can replace the fan itself from an identical PSU. It does mean taking the PSU out of the computer and fitting the fan yourself.
Alternatively you can purchase another PSU.


Aug 30, 2009 | Ultra (9PA3501609) 350-Watt Power Supply

1 Answer


Anytime you see a Green wire in a computer, (Personal Computer), power supply's ->power cable, it is for the Soft Power On function.
This way there isn't a cable, (Cord), going from the Power On switch to the power supply.
These are ATX style of power supply's.

The Black insulated wires are Ground wires. ALL of them.

There was a older power supply made, and this was the AT style.

To provide a solution, I'm going to give you some information on the power cables, for Both of these styles of power supply's, then some advice.

1.This is info, and photos of the older AT power supply's power cables,

2.This is the newer ATX style power cable, and more specifically the 20-pin version,
Scroll down the page to view the 24-pin power cable, and then scroll down some more, to view the 20+4-pin power cable.

ALL ATX design power supply's use Pin 16 for PS ON, (Soft Power On), which is a Green wire, and ANY Black wire. ALL Black wires are a ground. Pin 15 has a Black wire, and is normally used to put a jumper in, from it to Pin 15. This turns the power supply on. There will be a small spark, and the chance of getting shocked.

What you are doing essentially, is using a personal computer power supply as a laboratory power source, therefore I cannot advise you further, as it is a Safety Hazard.

Jul 31, 2009 | Dell POWER SUPPLY PS-5201-5D (PS52015D)...

1 Answer

No power on

if sb +5 is ok then check one by one these component :-
check main swithing transistor for open
check diode, capesetor and 3.3 ome resitor it may be open after then check
+ 12 to +18 volt for pwm ic and ,

if votage is not missing then change pwm ic

Apr 21, 2009 | Dell - NPS-200PB-73M (NPS200PB73M) Power...

2 Answers

Pyramid ps-15kx

Unplug the PS-15KX 120V AC cord !! Then take cover off. DO NOT plug the AC cord in unless you are used to working around a lethal voltage and current !!!!!!!!!!

If you can use a Multimeter, then measure resistance across each pair of the 3 leads of the output transistors. You will probably find fractions of an ohm across a pair of leads. One or both may be shorted. NOTE: Do not ever measure resistance in a powered up circuit, kiss meter bye-bye and maybe burn you too.

By putting more robust transistors in this supply, you may not gain much reliability. The supply is rated at a continuous current draw, which is less than the intermittent current they advertise. Read the spec's of any power supply you get and look for continuous current ability.

There are several better transistors that will substitute for the 2N3055. You will need to look at a transistor substitution book and check specs. The internet is great for this. I used to use all kinds of data books, and still have them! But looking up info on-line is nice. Motorola has some that will fit and have higher current and voltage ratings,

Get someone who is a ham or geek if you aren't sure about sticking your fingers in the power supply.

Be Careful, Work Safe, it is a factor of longer life.

Nov 08, 2008 | Pyramid 10 Amp Power Supply (068888701655)...

1 Answer


first you switch on the supply by shorting (green and black )wire in output socket of smps.then check output voltages.If there is no voltage then check switching transistors or protection transistos that is placed on first hit sink.check primary bridge and capacitors for open.

May 24, 2008 | Dell NPS-110AB (NPS110AB) 110-Watt Power...

2 Answers


Maximum output of any smps is not based solely on the type of power switching transistors used. One of the parameters which will be crucial is the Ic (Max collector current rating). But this by itself isn't the lone determining factor either.

Other design factors which will come into play are the switching transformer, its size and windings. A smaller transformer and smaller wire gauge windings will generally mean lower max power output.

Max power output measurements probably require a set of load resistors, volt and amp meters, monitoring the 3.3, 5, 12 volt lines.

I'm not an engineer, but have had numerous computer power supplies apart, repairing some, junking some. Quality of construction or lack thereof is generally obvious. PC Power and Cooling probably builds high quality units. There are plenty of cheap, low cost power supplies which frequently die after a year or two, sometimes taking a motherboard down with it.

Dec 21, 2007 | Compaq Refurbished 280WATT POWER SUPPLY...

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