Blown mje350 and led [REPAIR VID AT END] [resolved]

Ohm question. I have sonus faber concertino and concerto. Thoes are 6ohm. I assume there shouldn't be a problem there hasn't been for over a year. I have to look if the opt is wired 4 or 8. Which is recommended?
 
Rob Capizzi said:
Ohm question. I have sonus faber concertino and concerto. Thoes are 6ohm. I assume there shouldn't be a problem there hasn't been for over a year. I have to look if the opt is wired 4 or 8. Which is recommended?
Click to expand...
"Which is recommended?"

I recommend the one that sounds better to you.

:^) Both are reasonable choices from a technical perspective. But they will interact differently with the speakers, and the differences will likely be audible.
 
Paul Joppa said:
:^) Both are reasonable choices from a technical perspective. But they will interact differently with the speakers, and the differences will likely be audible.
Click to expand...

Ok thought so, thank you.  I've obviously googled it a bunch. I went to 4 ohms on the dynaco vta st120. I like it.
 
Once all the new components and tubes are in should I start the amp with a variac and take measurements or just turn it on with fingers crossed?
 
On the mje350
1.emitter
2 collector
3 base
MJE5731g
1 base
2 collector
3 emmiter
So I will install backwards.
 

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The MJE5731G I ordered is 350v
There is an mje5731AG that's 375v and available.
Should I have ordered the MJE5731ag ?
https://www.mouser.com/ProductDetail/onsemi/MJE5731AG?qs=R2UZ7gjkEjIIBIrVFKMX3w%3D%3D
 
Yes , the 375 volt will be more reliable. The higher voltage is the primary reason for changing from the MJE350.

If there were an even higher-voltage PNP transistor available, I would probably want to switch again.
 
Either one will work adequately in the Paramount.  The change is to buy a little extra tolerance to high voltage (the MJE350 is rated for 300V max) and to better handle the thermal requirements in that position.
 
The presence of the MJE350 in the original circuit was likely the cause of the fried zener diodes. 

Don't hesitate to clip a little heatsink onto the 5731A down the road if you can.
 
I will. I have mini ones that'll be perfect.  All of them I suppose could benefit, even the power supply board? What's the best way to attach? Thermal paste and maybe thin tie wire twisted.
 
I would just get some small clip on heatsinks for TO-220s.  I wouldn't glue anything on or use thermal grease, that's pretty overkill for the application. 
 
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