testing 2SJ162 & 2SK1058

[diyfmradio]

Hi
I just got a blown 100W power amp from a friend
and am busy fixing it

I would like to know how to test the output mosfets 2SK1058 & 2SJ162?...
as i don't know how to test mosfets!

I have already done the test on http://www.uoguelph.ca/~antoon/gadgets/mostest.htm
and it was sucessfull

Thanks in advance!

[jmateus]

I have a question about these devices and others.
I know these Mosfets are know as L-Mosfets, i.e. Lateral mosfets.
Not knowing exactly what this means, I would like to know if the
other Mosfets 2SJ49 and 2SK134 used in audio and also made by Hitachi are also L-mosfets. Another words are they the same type of Mosfets?
Is there anybody who knows about these nomenclatures? I´d
appreciate some info.

[jackinnj]

Hitachi is out of the Lateral MOSFET business - it's now owned by Renesas.

Here's a link to their product listing:
http://america.renesas.com/fmwk.jsp?...r_mos_gen_amp/

[richie00boy]

Test MOSFETs by measuring the dc resistance between source and drain. It should be very high resistance when off. They can also fail due to gate rupture due to excess voltage Vgs.

[diyfmradio]

Thanks richie00boy

they test ok will try them if they fail will replace them as I have a few....

Thank though

[richie00boy]

Note that they have a body drain diode to protect against back emf so one way will read low resistance if your meter test voltage is high enough.

[mzzj]

Use multimeter with diode treshold voltage measurement(or whatever it is called) First short all mosfets legs together, then measure between D-S in both ways, in reverse polarity you will get typically 0.4-0.8V reading because of body diode, and in normal polarity infinite reading. After that check Gate, in N-channel mosfet plus-lead to gate and and minus to source, again you should get infinite reading, if not, gate oxide is ruptured.

Now you can check DS diode drop again, meter should show very low reading( in both ways), something like 0.0xx because it is in ON-state now.

Depending on your multimeter and GS-treshold voltage, your mileage may vary but at least most Flukes and chinese 5Eur meters work perfectly.

[zinsula]

http://www.diyaudio.com/forums/showt...749#post632749

Cheers, Tino

[Panelhead]

Originally posted by mzzj
Use multimeter with diode treshold voltage measurement(or whatever it is called) First short all mosfets legs together, then measure between D-S in both ways, in reverse polarity you will get typically 0.4-0.8V reading because of body diode, and in normal polarity infinite reading. After that check Gate, in N-channel mosfet plus-lead to gate and and minus to source, again you should get infinite reading, if not, gate oxide is ruptured.

Now you can check DS diode drop again, meter should show very low reading( in both ways), something like 0.0xx because it is in ON-state now.

Depending on your multimeter and GS-treshold voltage, your mileage may vary but at least most Flukes and chinese 5Eur meters work perfectly.

This is how I match them up also. This on resistance is not as accurate as measuring current flow in real circuit, but is much better than just random selection.
There is a correlation between this on resistance and actual circuit performance.

George

[mzzj]

Originally posted by Panelhead


This is how I match them up also. This on resistance is not as accurate as measuring current flow in real circuit, but is much better than just random selection.
There is a correlation between this on resistance and actual circuit performance.

George

So do I. (when i tried to built dummy load with power mosfets, but i had to give up because paralleing power mosfets in this case is pain in *ss) Thanks to their widely variable GS threshold voltage vs. temperature. Bipolars are WAY much better in current sharing
Edit: I was blaming vertical mosfets, lateral mosfets are completely different case, but their price rules them out.