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Old 25th August 2010, 01:35 PM   #21
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Comments coming thick and fast! Thanks guys

I've removed the transformer from the case, but that's as far as I have got as I have been quite busy with 'real' work this morning. I will extend the power lines to and from the transformer a little later, enabling me to fire up the amp with the transformer free of the enclosure.

I will report back....
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Old 25th August 2010, 05:52 PM   #22
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Quote:
Originally Posted by AndrewT View Post
If you disconnect one channel and run the other as a monoblock, does it become hum free?

Where do the speaker leads connect? They both seem to go to the PCB.

Are the brass standoffs isolated from the PCBs?

Both of the speaker leads connect to the amp pcb as per cvillers diagram.

Brass stand-offs: I wanted to use fibre washers when putting this together but didn't use anything in the end. I don't think the holes are conductive, I may be wrong.

I haven't tried disconnecting one channel. I'll try it tonight
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Last edited by Tripmaster; 25th August 2010 at 05:58 PM.
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Old 25th August 2010, 05:57 PM   #23
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OK...I have pulled the transformer out and twisted the wires but the hum remains

Click the image to open in full size.

I was feel quietly confident as I flicked the switch
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Old 25th August 2010, 06:02 PM   #24
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Looks like you may have a ground loop within the amplifier.
Proper grounding is absolutely essential.
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Old 25th August 2010, 06:28 PM   #25
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Quote:
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Looks like you may have a ground loop within the amplifier.
Proper grounding is absolutely essential.
Could be.

I'll unscrew the screws from the brass stand-offs and place a piece of insulation tape between the board. It will be a good time to try this when disconnect one of the channels.
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Old 25th August 2010, 07:34 PM   #26
Puffin is offline Puffin  United Kingdom
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Jenga Technology is the problem.

"Jenga is a game of physical and mental skill created by Leslie Scott

You see, it'll take an awfully long time if you keep those blocks in place!
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Old 25th August 2010, 09:28 PM   #27
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Hi Andrew

Disconnecting channel: good suggestion!

I disconnected the left channel, and the right is completely silent. The same applied to the right

Hum loop it is
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Last edited by Tripmaster; 25th August 2010 at 09:44 PM.
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Old 25th August 2010, 09:35 PM   #28
Malka07 is offline Malka07  England
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Thats great news Richard

Now you just have to work out a way to break it!!! The loop that is

Made a little progress on mine too...buzz still there but hum much quieter...i am going on holiday to cornwall though, so wont be able to do anymore until i come back...i hope you get yours sorted soon.

Alon
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Old 25th August 2010, 09:39 PM   #29
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Quote:
Originally Posted by Malka07 View Post
Thats great news Richard

Now you just have to work out a way to break it!!! The loop that is

Made a little progress on mine too...buzz still there but hum much quieter...i am going on holiday to cornwall though, so wont be able to do anymore until i come back...i hope you get yours sorted soon.

Alon
And I'm going to Devon!

I read your post last night, very encouraging
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Last edited by Tripmaster; 25th August 2010 at 09:44 PM.
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Old 25th August 2010, 09:53 PM   #30
Malka07 is offline Malka07  England
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Have a great Holiday ...funny how we both have similar hum problems and also similar holidays

Alon
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