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Old 25th November 2006, 09:45 AM   #1
yoke is offline yoke  Croatia
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Default New AlephX - problem

Hi...
I have put together two channel of Aleph X...
One is working fine, except that heatsinks are little short so that temperature is 65*C, but the another gives me problem...

I just connected it for the firs time...and one side doesn't work?
When I say one side, I mean, when we divide this amp to + and – output side...Q1, Q2 doesn't work...Q10, Q11 does work...( I have 2xQ1,Q2 and 2XQ10,Q11 )
I measure voltage over source resistors on those mosfet and I get 0.5V on Q10, Q11 and 0V on Q1, Q2...

I try to swamp Q5 and Q7 and I get same thing...

What could be wrong?
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Old 25th November 2006, 10:15 AM   #2
Netlist is offline Netlist  Belgium
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What's the voltage over R23 and R25?

/Hugo
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Old 25th November 2006, 10:21 AM   #3
yoke is offline yoke  Croatia
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R25 2.9 and R23 4.6 at around +/-12V
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Old 25th November 2006, 10:40 AM   #4
Netlist is offline Netlist  Belgium
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R23 is correct. 2.9V over R25 is not enough to turn Q2 on. So, you'll have to find out why that voltage is too low. Correct resistor value? Bad soldering?

/Hugo
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Old 25th November 2006, 11:21 AM   #5
yoke is offline yoke  Croatia
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could it be that Q4 or Q9 ( ztx450 ) are broken ?
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Old 25th November 2006, 12:01 PM   #6
Netlist is offline Netlist  Belgium
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Could be, just take them out for the moment, the amp works fine without them.
In any case, you need exactly the same voltages at R23/25 and 2.9V is too low. Measure the voltage across the gate resistors of the output and current source mosfets.
They all should read 0V. If not, the corresponding mosfet is broken.

/Hugo
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Old 25th November 2006, 12:51 PM   #7
yoke is offline yoke  Croatia
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o.k....I replace ztx450...no change...
Change Q7 ( IRF9610 ) on R25 (¨the one that measures less then 0.4V ) ... no change...
I try to resoled resistors around Q5/Q7 ( on PCB )...no change...


Is there possibility to burn something while playing with this...I mean one side work, other don’t and there is above 10V on PCB ?


Netlist, thanks for your time and hlep
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Old 25th November 2006, 12:55 PM   #8
yoke is offline yoke  Croatia
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upppsssss

I just soo that I have solder R8 into the place of R7
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Old 25th November 2006, 01:00 PM   #9
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Again, what voltage do you read across the gate resistors of Q1 and Q2?

/Hugo
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Old 25th November 2006, 01:09 PM   #10
yoke is offline yoke  Croatia
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everithing is fine now...

thanks Hugo once again

it takes me only 3 and a half hour to figure that I solder resistor at wrong spot
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