Smoke coming out from my Aleph.... Please HELP! - diyAudio
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Old 3rd July 2006, 10:45 AM   #1
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Default Smoke coming out from my Aleph.... Please HELP!

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
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Old 3rd July 2006, 11:44 AM   #2
Netlist is offline Netlist  Belgium
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Angus,
A nice thing to start with is to tell us (link) which schematic you used, what rail voltage, and possible changes you made to the schematic.
I think with output R's you mean from output to ground but it's guesswork for now.

/Hugo
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Old 3rd July 2006, 12:11 PM   #3
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My Aleph-X compact PCB

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
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Old 3rd July 2006, 04:26 PM   #4
Netlist is offline Netlist  Belgium
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Sorry Angus, I can't go into debugging the board to reconstruct the schematic. Also, I need to know exactly what resistors were smoking.

/Hugo
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Old 4th July 2006, 12:05 PM   #5
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The resistor that is in smoke is the one parallel to the 33ohm resistor, which is in series with the Output.

But i do not understand why it doesn't not draw any current from the -V
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Old 4th July 2006, 01:11 PM   #6
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If you post a schematic I am sure Netlist and others can help you. With out one there is not much they can do.
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Old 4th July 2006, 01:13 PM   #7
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I found this in the thread from your GB. It looks like KK's.
Attached Files
File Type: pdf alephxcircuit.pdf (24.7 KB, 127 views)
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Old 4th July 2006, 02:03 PM   #8
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Quote:
Originally posted by eapavant
I found this in the thread from your GB. It looks like KK's.

That is the one, thank you for all your help.

Angus
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Old 5th July 2006, 05:16 AM   #9
EUVL is offline EUVL  Europe
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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
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Old 5th July 2006, 07:29 AM   #10
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How do i know there is a current of 1 A flowing?

Angus
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