Help bringing up Aleph2. (Smoke)

[Mad_K]

Some have said just leave R-18 out of the circuit if you have alot of heat sinking. Hs anyone reading this thread ever done this?
Mark

Yepp! (R19, that is...) On my Aleph30 with 1 ohm source res. I got 0,66-0,7V across the res.

😉

 

[Mark A. Gulbrandsen]

Hey Mads, youw right...if only my typting was halfp as gotod as the Aleph soundz,,,)$*^%@$()*&^%(*&@)(
Mark

 

[Mad_K]

Just measured it again; It starts at 0,7V and drops to 0,66V when it's getting warm...(1 hour+)

 

[jh6you]

... I don't know how this will effect the current source end of things but I'm don't think it'll matter too much.

I understand that it affects the current source (ac-current gain rate).
The lower current-sensing resistor values, the lower ac-current gain.
Anyhow, the size of the current-sensing resistors can not be the reason of Dale's problem.


JH

 

[harvardian]

Hi Guys,

Just to clarify and to put at ease those who recently bought boards or fets:

1) The Aleph2 is working!
2) The boards are the latest versions of both. There were no issues.
3) I grabbed my worst set of fets to bring up the amp.
4) I think that I actually ran the board on 140VAC, so my DC rails were 51.5V.

5) I checked all voltages on the driver board and all were in spec. The only problem now is that my voltages across the source resistors vary a little too much.

I may reduce my bias level until I replace the fets. I may also do some tweaking with the source resistors, but that would be messy.

Thanks for all of your help.

Dale