I purchased 2 pairs of 2SK1058 / 2SJ162 mosfets in order to repair a Hafler P3000 power amp. This amp has 2 identical boards, one for each channel. I've checked this amp before and everything was in order except the 2 pair of MOSFETs, so it was basically a "drop in and go" operation. When I dropped the new MOSFETs in the fuse burned out immediately after connecting the AC cord. I took out the new MOSFETS again and also a pair of the working channel and checked with my DMM. Turns out the new MOSFETs have polarity inverted on pin 2 and 3. This is not normal, I suppose...........
Thanks, nfsgame. I already suspected that they would be fake. I know about the 10N20 / 10P20 from Exicon, but I fell for the cheaper ones. Lesson learned.
But do these k1058 and J162 work at all? Maybe if I modify them to fit the corresponding holes in the PCB? I could attach wires to the legs and insert them in the right place.
1) they are completely different, in practically all aspects.
2) Even IF you modded PCBs so pins match, Biasing is completely different, thermal coefficient the opposite, etc.
Lateral (Audio) MosFets are self-stabilizing, need very little bias (a couple hundred mV), are very linear from low idle current up, etc. , which leads to simple and elegant designs.
Biasing can be achieved by a simple resistor, go figure.
Verticals (switching) ones are very non linear, need huge bias (think 3500mV class), have abrupt turn-on so crossover distortion is a danger, they are thermally unstable (compared to Laterals that is) so they need tight thermal tracking bias, etc.
You can make excellent amplifiers with them of course, just not plain replace one for the other.
2) Even IF you modded PCBs so pins match, Biasing is completely different, thermal coefficient the opposite, etc.
Lateral (Audio) MosFets are self-stabilizing, need very little bias (a couple hundred mV), are very linear from low idle current up, etc. , which leads to simple and elegant designs.
Biasing can be achieved by a simple resistor, go figure.
Verticals (switching) ones are very non linear, need huge bias (think 3500mV class), have abrupt turn-on so crossover distortion is a danger, they are thermally unstable (compared to Laterals that is) so they need tight thermal tracking bias, etc.
You can make excellent amplifiers with them of course, just not plain replace one for the other.