Need help with connections (Brian's LM3875 kit)

maurycy · 20th December 2011, 04:59 PM

Long story short: I am moving once completed LM3875 chipamp to a new case and adding second PSU board and second torroid. I had everything working with one trafo and one PSU board and since my electronics knowledge is limited, I am hoping that somebody here could take a look at the attached connections schematic and let me know if I got everything correctly or not.

connections

Because of the CT torroid, I have only four diodes in each PSU board and I have the necessary jumpers. They are just not shown here.

Thanks.

ByronInLawrence · 31st December 2011, 04:37 PM

Enclosed are the correct PS connections according to Brian's instructions. I don't know anything about the volume control.

AndrewT · 31st December 2011, 05:33 PM

Note that both "CHG" are connected to chassis.
Check thoroughly that this does not create a ground loop.

maurycy · 6th January 2012, 02:37 PM

Byron: Thanks for the new diagram. The problem is that my PSU board is modified and contains only 4 diodes (not 8) so PG- and PG+ are linked with jumper on the PSU board. I do not think there is need to run both to AMP board.

AndrewT: According to the documentation for dual-mono system, only CHG needs to be connected to the star ground. I will try that first and report if there are any hum problems.

dazzje · 24th June 2012, 03:00 PM

Quote:

Originally Posted by ByronInLawrence

Enclosed are the correct PS connections according to Brian's instructions. I don't know anything about the volume control.

Would you by any chance have a version of this diagram for the stereo build of the chipamp kit?

20th December 2011, 04:59 PM	#1
maurycy diyAudio Member Join Date: Dec 2005 Location: NJ	Need help with connections (Brian's LM3875 kit) Long story short: I am moving once completed LM3875 chipamp to a new case and adding second PSU board and second torroid. I had everything working with one trafo and one PSU board and since my electronics knowledge is limited, I am hoping that somebody here could take a look at the attached connections schematic and let me know if I got everything correctly or not. connections Because of the CT torroid, I have only four diodes in each PSU board and I have the necessary jumpers. They are just not shown here. Thanks.

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31st December 2011, 05:33 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Note that both "CHG" are connected to chassis. Check thoroughly that this does not create a ground loop.

6th January 2012, 02:37 PM	#4
maurycy diyAudio Member Join Date: Dec 2005 Location: NJ	Byron: Thanks for the new diagram. The problem is that my PSU board is modified and contains only 4 diodes (not 8) so PG- and PG+ are linked with jumper on the PSU board. I do not think there is need to run both to AMP board. AndrewT: According to the documentation for dual-mono system, only CHG needs to be connected to the star ground. I will try that first and report if there are any hum problems.