Mosfet Power dissipation question

[holmzy]

Re: Mosfet Power dissipation question

So adjust it to be 0mV +/- 30mV offset then.

LOL I was doing that then shorted the leads and blew the MOSFETs!

[budm]

Re: Mosfet Power dissipation question

I know you have blown the MOSFET's when you shorted the leads together so now you have new MOSFET's so why can't you adjust it be within the spec? It has 100mV offset right now, correct? Unless I read the whole thing wrong. Or are you saying you blown the NEW MOSFET's when you try to adjust the offset.
BTW, since NE is obsolete, hope the NE you find is not faked.
https://www.mouser.com/ProductDetail...%252BE9Q%3D%3D

[holmzy]

Re: Mosfet Power dissipation question

Yes the new NF replacement I blew also. The original I blew touching the speaker cables and the NF I blew by touching the DC offset leads!

I have found a source who claims to sell originals. But as mentioned I need to understand this Power Dissipation thing before I decide on the transistors as I'm worried about the heat produced

[budm]

Re: Mosfet Power dissipation question

Try checking the idling current sensing 2 Ohms resistor and Diode of the blown channel (I do not know which channel was blown) R321/D305(L) and R421/D405 (R) to make sure they are not damaged. At 180mV of bias setting, the idling current will be 180mV/2 Ohms = 90mA. May be the value of the resistance has gone down so to get the 180mV reading the idling current has to go up.
Regarding to the MOSFETs, I do not see any graphs for the NE so you can compare the difference in details to the NF, in the idling mode we do not know what the Rds is to calculate the power dissipation at 90mA of current.