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Old 1st December 2012, 05:59 PM   #31
anilva is offline anilva  India
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I have had problems with similar PCB. After trying everything like you, I changed the caps from 15000 uF to 22000 uF and everything become quite. My 2 cents.
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Old 1st December 2012, 09:54 PM   #32
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Quote:
Originally Posted by anilva View Post
I have had problems with similar PCB. After trying everything like you, I changed the caps from 15000 uF to 22000 uF and everything become quite. My 2 cents.
The hum disappeared?
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Old 2nd December 2012, 04:55 AM   #33
anilva is offline anilva  India
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Quote:
Originally Posted by Blink_PT View Post
The hum disappeared?
Yes.
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Old 2nd December 2012, 11:32 AM   #34
AndrewT is offline AndrewT  Scotland
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reduced or eliminated hum, due to replacing bad capacitors, or bad soldering.
Not to do with the change from 15mF to 22mF.
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Old 2nd December 2012, 11:34 AM   #35
AndrewT is offline AndrewT  Scotland
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Blink,
Please attach your pics.
You have no idea how much these remotely located pics slow down the page load, due to automatic download of the full pic file/s. Compared to attached pics, which download the thumbnail and leave the big pic download as an option.
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Old 3rd December 2012, 06:05 AM   #36
omishra is offline omishra  India
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Quote:
Originally Posted by AndrewT View Post
reduced or eliminated hum, due to replacing bad capacitors, or bad soldering.
Not to do with the change from 15mF to 22mF.
What is effect of PS ripple over the output? Isn't less ripple less hum?
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Old 3rd December 2012, 10:07 PM   #37
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Quote:
Originally Posted by AndrewT View Post
Blink,
Please attach your pics.
You have no idea how much these remotely located pics slow down the page load, due to automatic download of the full pic file/s. Compared to attached pics, which download the thumbnail and leave the big pic download as an option.
Hello,

Now put by another process, hope you see the images.

If you disconnect the Interconnects do not hear any hum, connecting ICs appears a little hum, so many experiences that I've done I can only doubt is that the defect PCBs.

The grounds were all disconnected cables IECm but does not change anything!

greetings
Attached Images
File Type: jpg F5humb.jpg (238.2 KB, 117 views)
File Type: jpg F5huma.jpg (183.0 KB, 112 views)
File Type: jpg F5 meu1.jpg (686.2 KB, 108 views)
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Old 4th December 2012, 09:23 PM   #38
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Hi Blink_PT

Let's do some debugging of your grounding arrangement.

All I will say is referring to the pics in your last post.

1- The wire from the loudspeaker return, the black output terminal, must be connected to the 0 of the power supply, near the electrolytic capacitors.

2- The ground terminal of both RCA input connectors must be connected together via a wire ( not too thin, and if possible, solid core).

3- The middle point of this wire must be connected to the 0 volts power supply reference, joining the loudspeaker return wire ( see 1). Once again use a not too thin wire.

4- From the input boards to the RCAs, take out the coaxial and use a not too thin wire between boards and the RCA grounds. Obviously you must do it in both channels. Later if you prefer you can use a coax, but with screen connected just at one end, that way it will carry no signal.

Good grounding practices keeps hum away...

That's all folks.
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Old 4th December 2012, 11:01 PM   #39
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Quote:
Originally Posted by Tube_Dude View Post
Hi Blink_PT

Let's do some debugging of your grounding arrangement.

All I will say is referring to the pics in your last post.

1- The wire from the loudspeaker return, the black output terminal, must be connected to the 0 of the power supply, near the electrolytic capacitors.

2- The ground terminal of both RCA input connectors must be connected together via a wire ( not too thin, and if possible, solid core).

3- The middle point of this wire must be connected to the 0 volts power supply reference, joining the loudspeaker return wire ( see 1). Once again use a not too thin wire.

4- From the input boards to the RCAs, take out the coaxial and use a not too thin wire between boards and the RCA grounds. Obviously you must do it in both channels. Later if you prefer you can use a coax, but with screen connected just at one end, that way it will carry no signal.

Good grounding practices keeps hum away...

That's all folks.
Hello,

Thanks Jorge for your help, but I have some questions to confirm.

I made a little diagram of what you said, and I look like this:

The Amp GND of right and left (R1 and R2) and R10 will not connect GND PSU?

The big currents working in loudspeakers should not return to the center point of the capacitors?

Blink
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Old 4th December 2012, 11:10 PM   #40
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with the last drawing, you have a grondloop between preamp and PSU of your amp.
ground your signal on each amp board. then connect audioground from each amp to PSU. AND a big fat wire from one amp board to the ground on the other amp board.

Last edited by AudioSan; 4th December 2012 at 11:12 PM.
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