Transformer Screen & Signal Grounding Issues

[Tripmaster]

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....

[Tripmaster]

Originally Posted by AndrewT

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

[Tripmaster]

OK...I have pulled the transformer out and twisted the wires but the hum remains



I was feel quietly confident as I flicked the switch

[Frank Berry]

Looks like you may have a ground loop within the amplifier.
Proper grounding is absolutely essential.

[Tripmaster]

Originally Posted by Frank Berry

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.

[Puffin]

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!

[Tripmaster]

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

[Malka07]

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

[Tripmaster]

Originally Posted by Malka07

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

[Malka07]

Have a great Holiday ...funny how we both have similar hum problems and also similar holidays

Alon