Todya, just now, i have powered up my Aleph-X with a vairable transformer, and after about 30 seconds, there are smoke coming out from the output resistor, but when i switch it off, i cannot feel any thing whihc is hot.
And i have notice a strange thing is the cirucit does not draw any power from the -V supply, as when i switch it off, the voltage accross the -V supply doesn't drop. but the +V voltage drops quickly.
Thank you for your kind attention to this thread. This is my first aleph. And i want it to work.. Please help!
Angus
And i have notice a strange thing is the cirucit does not draw any power from the -V supply, as when i switch it off, the voltage accross the -V supply doesn't drop. but the +V voltage drops quickly.
Thank you for your kind attention to this thread. This is my first aleph. And i want it to work.. Please help!
Angus
http://www.diyaudio.com/forums/showthread.php?s=&threadid=67389
This is the board which i am using, i ma uisng a rail voltage of 20V, smoke coming out when it is tested at +-17V. The BIAS current is 6A.
Angus
This is the board which i am using, i ma uisng a rail voltage of 20V, smoke coming out when it is tested at +-17V. The BIAS current is 6A.
Angus
Angus,
Try the following first to see if the diff pair is working / adjusted properly.
Disconnect the power boards completely from your frontend board. Change R3/R53 to 100k. Tie both +ve & -ve inputs to ground. Power up and adjust VR101 until the voltage across R3 & R53 are approx. 3.9V.
If this is OK, you should get about 1A flowing through each of the lower MOSFETs.
I am on trip at the moment. But I am sure other can / will help.
Patrick
Try the following first to see if the diff pair is working / adjusted properly.
Disconnect the power boards completely from your frontend board. Change R3/R53 to 100k. Tie both +ve & -ve inputs to ground. Power up and adjust VR101 until the voltage across R3 & R53 are approx. 3.9V.
If this is OK, you should get about 1A flowing through each of the lower MOSFETs.
I am on trip at the moment. But I am sure other can / will help.
Patrick
But it said i have to disconnect all the power boards completely from your frontend board. And i think the source resistor is on the power boards.
So what i have to do is to Change R3 and R53 from 10k to 100k and then disconnect all the fets and then addjust the VR101 and then measure the voltage accross the source resistor on the power board (0.33 Ohm) and use V=IR calulation to calculate the current
Angus
So what i have to do is to Change R3 and R53 from 10k to 100k and then disconnect all the fets and then addjust the VR101 and then measure the voltage accross the source resistor on the power board (0.33 Ohm) and use V=IR calulation to calculate the current
Angus
> But it said i have to ....
Angus, you don't have to do anything. It was just a suggestion.
> disconnect all the power boards completely from your frontend board. Change R3 and R53 from 10k to 100k and then disconnect all the fets and then adjust the VR101 and then measure the voltage across ......
.... the Drain resistor of the diff pair (R1 / R51) to about 3.9V. This will prove that at least your frontend diff pair works. The Aleph current source is difficult to adjust without the power MOSFETs, so you'll have to do it in the next step. One step at a time.
Don't worry about your bias current as yet. Just make sure the frontned works. There is little to go wrong at the power stage.
It would help a lot if you read the Wiki and try to understand how the circuit works.
Patrick
Angus, you don't have to do anything. It was just a suggestion.
> disconnect all the power boards completely from your frontend board. Change R3 and R53 from 10k to 100k and then disconnect all the fets and then adjust the VR101 and then measure the voltage across ......
.... the Drain resistor of the diff pair (R1 / R51) to about 3.9V. This will prove that at least your frontend diff pair works. The Aleph current source is difficult to adjust without the power MOSFETs, so you'll have to do it in the next step. One step at a time.
Don't worry about your bias current as yet. Just make sure the frontned works. There is little to go wrong at the power stage.
It would help a lot if you read the Wiki and try to understand how the circuit works.
Patrick
> So for now, i disconnect all the power boards and then measure the voltage. of R1/R51 or R3/R53. Which pair is correct?
R1/R51, the 2x 390ohm resistors at the drain of the IRP9610s.
Was typing mistake with R3/R53 in post #9. And don't forget to connect both inputs to ground temporarily.
Patrick
R1/R51, the 2x 390ohm resistors at the drain of the IRP9610s.
Was typing mistake with R3/R53 in post #9. And don't forget to connect both inputs to ground temporarily.
Patrick
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