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Could change MJF15031 for MJE15031?

I bought more transistors and I have four MJF15030 (lot: SPB16 - HFE=175,178,182,184) and 4 MJE15031 (I'm not sure of the manufacturer, lot: MA0 5K - HFE=180,185,190,190).

Can I combine these MJF and MJE in this amp?

 

-- o --

Rodrigo

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My Krell:        

Got it cased.  Pretty standard.  I apologize for the power switch--I couldn't resist.  

I completed the full modification (output stage and front end) on both channels and listened to the amp briefly. The headphones were Grado GS1000 and Sennheiser HD595, the 8ohm speaker were B&W 60

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So I'm the only one using the 2.5" sinks?  :)  They fit the chassis so why not...

 

I got my panels back from the laser but the guy destroyed the front panel (don't ask).  So I'll either have to use the back which is the suck in terms of finish or steal a fresh one from my stock and get a replacement sent with the next order. 

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I have the bigger heatsinks but one of the holes seems to limit

The thermal efficiency. Will test...

Would be nice if there was a taller heatsink with only one hole

Edited by kevin gilmore
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The mounting is not as nice, that for sure.  One odd thing, I've ordered a lot of the larger 2.5" sinks and some have shown up with the cutouts while others have just had one mounting hole.  Same Mouser number... 

 

Would be nice if there was a taller heatsink with only one hole

 

*Calling Steve to the local Krell thread....  Steve to the Krell thread....*  ;D

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so what we really want is avid part number

 

513202b02500g  which is 2.0 inches high or

 

513302b02500g which is 2.5 inches high

 

which is the to220 only version

 

neither of which are stocked by digikey or mouser

 

instock at Newark

Edited by kevin gilmore
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The mounting is not as nice, that for sure.  One odd thing, I've ordered a lot of the larger 2.5" sinks and some have shown up with the cutouts while others have just had one mounting hole.  Same Mouser number... 

 

 

*Calling Steve to the local Krell thread....  Steve to the Krell thread....*  ;D

 

Damn! Another missed opportunity.

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What is the current draw in each output transistor on the original unit?

When I set it for 100mA, 1.5inch heatsink gets really hot.

 

its less than that, but I have that info at home.

will look later. specific voltage across the emitter resistors.

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ok, so the krell documentation is a little questionable, but when they measure the bias they

do it from emitter to emitter. so the number is twice as big as the two test points I put on the board.

 

specifically its 250 millivolts emitter to emitter cold, and 180 to 200mv hot.

 

so at the two test points provided its 125 millivolts emitter to output no load cold a,d 90 to 100 millivolts hot.

 

which sounds about right.

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Mine is finish since a week, and when I start it, he smoke >:(

After some reseach, I found that the 500R ajustable was 500K !! Mouser make a little mistake !

 

I hope that with the good value, everything will be fine...

 

yep that is going to cause smoke.

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