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From: s36572u@puukko.hut.fi (Karl R. Tigerstedt)
Newsgroups: comp.sys.mac.hardware
Subject: SID II problem
Message-ID: <1990Sep24.112557.2941@santra.uucp>
Date: 24 Sep 90 11:25:57 GMT
Sender: news@santra.uucp (Cnews - USENET news system)
Reply-To: s36572u@puukko.hut.fi (Karl R. Tigerstedt)
Organization: Helsinki University of Technology, FINLAND
Lines: 24


     I just purchased the SID II, assembled it - it didn't work.
When I tried to record, the only sound I could get was a very
high-pitched tone. Looked at the thing with an oscilloscope, the
A/D chip was receiving this signal - so the problem had to be
somewhere around the filter unit (the TL064 or was it TL084, not important).
	Anyway, I changed one of the 1 uF capacitors (the one that is
sort of fed back around the first op. amp.) to 820 nF, and the problem
was gone. No more high frequency tones, that block all else. 
	But, now when I record, the sound quality is very poor, even
at a sampling rate of 22khz. It seems that the bass tones are completely
cut off, maybe due to the change I made. When I played back the
"welcome to SID II from Cedar Technologies" -recording, I was amazed
how nice it sounded compared to the mumble I get.
	My question is: What is really wrong with my SID?
			Which component(s)?


P.S Sorry, but I don't have schematic right now, but I'll look it up
    more precisely, if needed.

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