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Old 29th February 2012, 10:21 AM   #1011
ENSen is offline ENSen  Sweden
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Check the F5 thread, someone had a similar problem. Also make sure that the RCA connectors are isolated from the chassis.
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Old 29th February 2012, 10:56 PM   #1012
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Originally Posted by JimM View Post
On my ba2 boards the front end ground's are separate, so if you only have one side of the front end board grounded then the other side is not tied to ground you need to tie both front end grounds to the common ground point. If I understand what you have written i.e. Only one ground of the front end is returned to the main star ground.
Dear JimM
It is a dual mono configuration with separate power supply's one unregulated for the output stage and one regulated for the front end the only common thing that the two channels are charring is the transformers one for the output and one for the front end.
That means that i have actually two common star grounds.
One on itch channel capacitor philter pcb all gnd's per channel are returning to its own assigned common gnd (0) point (one gnd from the front end & one from its power supply).
The RCA inputs are isolated from the chassis.
Can someone advise on ground wiring on this setup !!!!
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Old 29th February 2012, 10:58 PM   #1013
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Originally Posted by ENSen View Post
Check the F5 thread, someone had a similar problem. Also make sure that the RCA connectors are isolated from the chassis.
Dear ENSen
The RCA input connectors are isolated from the chassis.

Thanks
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Old 1st March 2012, 01:00 AM   #1014
Tea-Bag is offline Tea-Bag  United States
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I think I am using JIM's boards for my front end,
and I have all the grounds tied to the central point on a copper strip in the center of the dual rail supply.
It's not audibly noisy, and a scope shows this as well.
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Old 1st March 2012, 11:08 AM   #1015
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Originally Posted by nikosgrgr View Post
Dear JimM
It is a dual mono configuration with separate power supply's one unregulated for the output stage and one regulated for the front end the only common thing that the two channels are charring is the transformers one for the output and one for the front end.
!!!![/U]
There is probably a difference in resistance between your two star grounds and I don't see the reason for two separate connections here (I may be wrong here so see what the others say on this issue).
Also you may have some resistance issues if you are connecting the star ground to the chassis earth via two separate diode arrangements.
I would establish a single common star ground for both channels, don't use two separate ones.
This single star ground for both channels can be connected to the chassis then via a CL60 thermistor just to simplify matters. If that works and you want to put back the diode arrangement then go ahead and try it.
Also, have you carefully checked all your voltage regulators and do their grounds link to each star ground?
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Old 2nd March 2012, 12:55 PM   #1016
JimM is offline JimM  United States
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From looking at your pictures and what you have said it appears you have one common transformer feeding both regulators and power supplies. I would think you need to have a common ground for both sides or have seperate transformers per side. I would trouble shoot the problem starting with a good ohm meter and check for continuity from centeral ground (star ground, signal ground) to points on pc boards and power supplies.
Then check to see if chassis ground is tied to signal ground. I think if you will tie all star grounds and power supply grounds to one point you will fix your problem. Also what is your regulated voltage and unregulated voltages? Very impressive lay out send more pictures also how is your ac in wired to xformer.
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Old 3rd March 2012, 09:09 PM   #1017
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Quote:
Originally Posted by JimM View Post
From looking at your pictures and what you have said it appears you have one common transformer feeding both regulators and power supplies. I would think you need to have a common ground for both sides or have seperate transformers per side. I would trouble shoot the problem starting with a good ohm meter and check for continuity from centeral ground (star ground, signal ground) to points on pc boards and power supplies.
Then check to see if chassis ground is tied to signal ground. I think if you will tie all star grounds and power supply grounds to one point you will fix your problem. Also what is your regulated voltage and unregulated voltages? Very impressive lay out send more pictures also how is your ac in wired to xformer.
Dear JimM thanks for your advise

You can see a detail layout of the wiring and some constraction photos.
One thing that i have notice also is that the transformer of the unregulated supply is bazing excessively and this mechanical noise is audible thru the speakers.


p/s



Regulated voltage +/-25VDC (200mA) per channel for Front End.
Unregulated for the output stage is +/-22,7VDC (2,7Amp) per channel.
Attached Images
File Type: jpg BA-2 WIRING.JPG (165.0 KB, 303 views)
File Type: jpg P6220652.JPG (118.6 KB, 245 views)
File Type: jpg PB290880.JPG (150.7 KB, 240 views)
File Type: jpg P6220655.JPG (108.6 KB, 238 views)
File Type: jpg PB290884.JPG (130.0 KB, 231 views)
File Type: jpg P6220656.JPG (104.5 KB, 126 views)
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Old 3rd March 2012, 11:57 PM   #1018
JimM is offline JimM  United States
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I think I would tie all signal grounds to one point including unregulated and regulated supplies together at one point, this should not hurt any thing if wired as shown on drawing. The other thing I would try and you may won't to do this first is bypass the soft start circuit.
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Old 3rd March 2012, 11:59 PM   #1019
JimM is offline JimM  United States
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I assume all the voltages at the boards are correct as measured with a meter.
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Old 4th March 2012, 09:35 PM   #1020
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[QUOTE=nikosgrgr;2932090] One thing that i have notice also is that the transformer of the unregulated supply is bazing excessively and this mechanical noise is audible thru the speakers.
QUOTE]

What current and voltage is your transformer primary winding designed for? Buzzing can be caused by saturation i.e., transformer can't cope with the primary voltage.

Does it buzz when connected to the house power supply but with the secondaries unconnected?
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