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Old 22nd January 2008, 02:19 PM   #1
Thago is offline Thago  Belgium
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Question Aleph 2 Differences in power consumption

So, finally, after > 6 months, I finalised my 2nd Aleph 2 monobloc (will post some pictures later).
I fired them up last Sunday, and they sound so great!! (I'm not so good in hifi-magazine like superlatives, but I agree on everything that has been written on this forum about the sound of Aleph's)

But... after they were playing some time I noticed that one of the monoblocs gets hotter than the other one. The largest difference is measured at the current source transistors: warm heatsink (you can leave your hand on for a long while) for one monobloc vs. hot heatsink (you would want to retrieve your hand after a couple of seconds, but not so hot that you would burn your hand) for the other one. I also noticed that the hottest monobloc draws appr. 1.7A from the power line, while the cooler one draws appr. 1.5A (both at appr. 230V).
I cannot really say that I hear a difference between both channels. I am now wondering what could cause this difference. And if something is wrong, should I than suspect the hot or the cool one? And where should I search the problem, if any?
Thx in advance for answering!
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Old 22nd January 2008, 03:01 PM   #2
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I suggest that you measure the DC drop across the Source
resistors of each output device. They should be be consistent.
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Old 22nd January 2008, 08:44 PM   #3
Thago is offline Thago  Belgium
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Hello Mr. Pass

It is incredibly encouraging for me to be advised personally by you!
I did as you told me, and measured the dc voltage across the source resistors.
I fist measured the gain devices, and voltages were all in the 0.37-0.38V range.
Then I measured the constant current devices, they showed voltages in the range of 0.45-0.46V, except the fift device: 0V!!
I removed the PCB from the heat sink, and guess what: I found one bad solder joint! I've repaired it, and now voltages over the source resistors of the gain devices are in the 0.47-0.48V range. Problem solved!

Thank you for sharing your IP rights with the DIY community!

Greetings from Belgium
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Old 22nd January 2008, 08:50 PM   #4
Netlist is offline Netlist  Belgium
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Care to share a few pictures, if any?

/Hugo
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Old 22nd January 2008, 09:17 PM   #5
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Quote:
Originally posted by Thago
Then I measured the constant current devices, they showed voltages in the range of 0.45-0.46V, except the fift device: 0V!!
I removed the PCB from the heat sink, and guess what: I found one bad solder joint! I've repaired it, and now voltages over the source resistors of the gain devices are in the 0.47-0.48V range.
We always measure the current through each Mosfet.
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