Hardware Insights Forum

Hi,
I have an old power supply which used single 10N90 MOSFET in primary high voltage section in place of double MJE13007 transistors pair . This single 10N90 can deliver upto 40A current . And two MJE13007 transistors can deliver upto 16A + 16A = 32A current . May be this is why - they have replaced double MJE13007 transistors just with a single 10N90 MOSFET . This 10N90 MOSFET has gone of that power supply .

Now the problem is - I am not finding any such high rated MOSFET in my market . But yesterday in the old electronics market I have found a big MOSFET which number is 2SK2078 . I have watched the data sheet ... it is a MOSFET of 27A .

As far as I have seen - Most Manufacturer of Power supply use double MJE13007 transistors which deliver 16A + 16A = 32A current for building a 500W power supply . And these two MJE13007 transistors works fine with 500W PSU .

Now my question - Can I use this 2SK2078 MOSFET instead of 10N90 ? Will a 500W PSU work with 27A MOSFET ? Will it be too much problem ?? Please help me ....... I am in confusion !

I am attaching datasheet both of the MOSFET below . Please have a look :

Galib wrote:As far as I have seen - Most Manufacturer of Power supply use double MJE13007 transistors which deliver 16A + 16A = 32A current for building a 500W power supply . And these two MJE13007 transistors works fine with 500W PSU .

No ___13007 transistor will deliver 500W, no matter what the label on the PSU says. On every PSU with 13007 switching transistors I have come accross, they explode under 320W load, even when the label says it's a 550W.

Galib wrote:Now my question - Can I use this 2SK2078 MOSFET instead of 10N90 ? Will a 500W PSU work with 27A MOSFET ? Will it be too much problem ??

I would probably work, but it will reduce it's maximum output capacity somewhat. It was probably a 300W unit with the 10N90, but it will now be a 200W with the 2SK2078

I should perhaps add, though that 200W will be adequate for a basic PC

Thanks c_hegge for your helpful suggestion . I want to use it for my own PC . My PC is an old model . It has P4 processor and Motherboard, DDR1 RAM, 160GB Hard Disk and a DVD-ROM . I think 200W is quite enough for my PC . What do you say ?

Just 1 hour ago I found a small MOSFET which number is FQPF10N20C . But the datasheet says - it is MOSFET of 38A but Volt specification is 200V

I am not able to add the Datasheet due to PDF Extension and file size more than 256KB is not supported here . So, the link is below :
http://www.alldatasheet.com/datasheet-pdf/pdf/94313/FAIRCHILD/FQPF10N20C.html

Is the Volt specification important there ? I have checked the PCB - Source is connected with Main Ground by a 0.1Ω, 2W Resistor, Gate is connected with 3842 feedback IC and Drain is connected with Transformer . So, which is important here - Is it Voltage or Ampere draw ?? Will 200V be any problem here ? Here is mentioned that - FQPF10N20C MOSFET size is TO-220 package .

I believ the voltage would be important here, so stick with the 2SK2078.

As long as you're not using a powerfull graphics card, 200W should be enough for your system

OK, I will go with you .