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Bosoz - AKSA problem
Bosoz - AKSA problem
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Old 2nd October 2004, 07:57 AM   #1
gchrist is offline gchrist
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Join Date: Mar 2002
Location: Athens Greece
Default Bosoz - AKSA problem

Today I finished my Bosoz.
I connected my preamp to a small midi system with an input to see if everythink was ok. I gave the preamp some music and I heard music from the midi system. Without a music signal I could not hear any buzz or other noise.

I then connected my Bosoz to my AKSA 55W power amp. I immediatly hear a strong buzz and I smelt something wrong in my power amp. I closed everything down and played the power amp direclty from my cd player. Everythin was ok. The only problem I noticed is that now I can hear a power on and power off screech noise from the power amp for some milliseconds. Previously it was silent.

So the question is: Why is my Bosoz not cooperating with my AKSA preamp?

What may be the problem?

How can I measure my preamps output DC voltage with a DVM?

What may have been damaged in my power amp?

I have measured my Bosoz based on the original article and I got all the measurements correct.

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Old 3rd October 2004, 01:29 AM   #2
Nelson Pass is offline Nelson Pass  United States
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Join Date: Mar 2001
Bosoz - AKSA problem
Most likely culprit is the output of the amplifier bleeding back
to the input of the preamp, and forming a feedback loop that
oscillates, usually up around 100 KHz. This would tend to make
the resistor in the amp's output RC network toast up a bit, but
is probably OK. Look for an ungrounded cable connection or
shield. If you don't use shielded interconnects, consider them.
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Old 4th October 2004, 05:01 AM   #3
gchrist is offline gchrist
diyAudio Member
Join Date: Mar 2002
Location: Athens Greece
Mr. Pass,

Thank you for your swift reply. I think that I may have traced the problem to a grounding error in my power amp. I will try to solve this problem and once solved I hope that my Bosoz will be displayed on your diy site also.

Best regards
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Old 5th October 2004, 05:08 AM   #4
gchrist is offline gchrist
diyAudio Member
Join Date: Mar 2002
Location: Athens Greece
Thumbs up Problem solved

I have solved this problem. In my power amp I had shorted the heatsink of a rectifier diode to the bottom of the chassis. Everything fixed now and working fine.

I will post some pictures today on a different post.

Thank you
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