D
Deleted member 543346
Hi.
I am currently rebuilding an Accuphase P - 266 , that came with blown outputs.
Seems the 2sk413 and 2sj118 is well out of production , and the few sources i find is kinda risky.
Is there a substitute that can be used for theese mosfets?
Hopefully something being sold at mouser , digikey or similar
I am currently rebuilding an Accuphase P - 266 , that came with blown outputs.
Seems the 2sk413 and 2sj118 is well out of production , and the few sources i find is kinda risky.
Is there a substitute that can be used for theese mosfets?
Hopefully something being sold at mouser , digikey or similar
D
Deleted member 543346
Based on the data sheets
https://www.web-bcs.com/pdf/Hit/2S/2SK413.pdf
https://www.web-bcs.com/pdf/Hit/2S/2SJ118.pdf
the vto is about 3.5V, so these are ~typical MOSFETs and I would try something like IRFP240 and IRFP9240, but some adjustment may be required to the bias.
However, any time you get an amp that has "blown up", you should look carefully at the design to determine how that happened, especially with MOSFETs. Replacing parts and hoping for the best is likely an exercise in futility. If you want this amp to work better than its unfortunate past, you have to improve it. This may not be as difficult as it sounds because so many "audiophile" amps are built by zealots who are not the best engineers. I would get the schematic and run simulations to determine the phase margin, thermal stability etc.
https://www.web-bcs.com/pdf/Hit/2S/2SK413.pdf
https://www.web-bcs.com/pdf/Hit/2S/2SJ118.pdf
the vto is about 3.5V, so these are ~typical MOSFETs and I would try something like IRFP240 and IRFP9240, but some adjustment may be required to the bias.
However, any time you get an amp that has "blown up", you should look carefully at the design to determine how that happened, especially with MOSFETs. Replacing parts and hoping for the best is likely an exercise in futility. If you want this amp to work better than its unfortunate past, you have to improve it. This may not be as difficult as it sounds because so many "audiophile" amps are built by zealots who are not the best engineers. I would get the schematic and run simulations to determine the phase margin, thermal stability etc.
D
Deleted member 543346
Thanks steveu.
Those Irfp's does look like a close enough replacement.
Yes there was some smaller transistors that was cracked , resistors burned and capacitors that measured with high esr.
Due to heat i have to repair some traces a few places around the burned areas.
I managed to get some second hand "original' mosfets , but i am not fully confident on their preformance yet.
Plan to use dimbulb tester and variac on first tests.
Those Irfp's does look like a close enough replacement.
Yes there was some smaller transistors that was cracked , resistors burned and capacitors that measured with high esr.
Due to heat i have to repair some traces a few places around the burned areas.
I managed to get some second hand "original' mosfets , but i am not fully confident on their preformance yet.
Plan to use dimbulb tester and variac on first tests.
