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#1 bt0200

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Posted 07 April 2005 - 09:40 AM

Hello, I should have schematic for an old D75 (not D75A).
Serial no is 16202.

Want to restore it. One channel is working the other is almost quiet and heavily distorted. I have got a copy of a D75A schematic from your representative
here in Germany (AudioPro). But at home again, I noticed that it doesn't match my amplifier. I think, they do not have any other schematic because I told them that I have got an old D75 and they didn't ask for the serial number.

Mine uses 2 dual-opamps (RC4558 and presumably MC1303, which once has  been replaced by a TBA231). The schematic shows a single quad-opamp (MC33079).
I would appreciate also a notice how to adjust bias current.

Thanks in advance

#2 DGlass



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Posted 07 April 2005 - 10:41 AM


It sounds like they gave you a schematic for a D75A.
While supplies last the original D75 Owners Manual and the D75 Service Manual for the non-A amplifier are still available for purchase from our Parts Department. You can either order then directly from us or from "Audio Pro" our distributor there in Germany. The part number for the manuals are below.

D75 Owners Manual Crown part# K80000E1
D75 Service Manual Crown part # 80186A6

#3 KGring


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Posted 07 April 2005 - 11:15 AM

The Older D75s had 2 dual opamps. The RC4558 and an LF357.
Please send me your email to kgring@crownintl.com and I will send you a copy of an older schematic. The exact schematic for your serial number is not available in electronic format.
Kevin B. Gring
Crown Audio