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MA-2400


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#1 dynamic

dynamic
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Posted 10 May 2006 - 11:41 PM

Hi all,
Can anyone steer me toward the apparent fault I'm having with a newly aquired Macro-Tech 2400. The amp seems to work well, BUT, around 900HZ there seems to be a steady hi-frequecy roll-off where Hi's are gone by 15Khz. This only happens in the right side channel.
Of special note; This amp was probably filthier than any I've ever seen. After a thourogh cleaning the problem seemed to temporarily go away. But I may have imagined it, as the loss is still apparent.
Is this a sign that I may be about to lose a transistor bank??
Thanks for your help,
Rick

#2 dynamic

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Posted 11 May 2006 - 07:54 PM

anyone wondering- as advised by Crown to check a specific circuit relating to ODEP limiting. Reason as amp being run clogged with filth for so long (no filter doing the boom-boom in a rave club over three years).
So amp may be exhibiting false triggering as devices have not yet been checked.

So when I check this out I'll relay my results.
Thanks Kevin!
Rick

#3 dynamic

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Posted 13 May 2006 - 11:46 AM

QUOTE(dynamic @ May 11 2006, 07:54 PM)
anyone wondering- as advised by Crown to check a specific circuit relating to ODEP limiting. Reason as amp being run clogged with filth for so long (no filter doing the boom-boom in a rave club over three years).
So amp may be exhibiting false triggering as devices have not yet been checked.

So when I check this out I'll relay my results.
Thanks Kevin!
Rick
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So .... looking at PNP/NPN sense circuits as our possible problem, this turns out negative as all 100z resistors (R125,126,135,137 are spot on). ..........

At this point, I'm waiting for my replacement oscilloscope to arrive. My old one's CRT went dead so my diagnosis is limited to what I can get from my sine wave generator and a few other tools. By the way, for anyone in need of a inexpensive scope, I was amazed at the availability of them on e-bay. $ 40. for mine. NO, it's not dual trace and probably not as good as yours, but hey.......