Hi,
Many years ago I built the Maplin Millenium stereo kit using one power supply section which sits left side. It sounded great but I put it in storage very quickly as it had a fairly loud buzz, not from the speakers, but from itself. During the silence between tracks, I could hear the thing from a few metres away.
I would now like to reinstate it and intend to part dismantle it and pretty the casework and upgrade some caps and wiring. I tried it briefly and it still works the same.
Any advise on the hum/buzz would be greatly appreciated.
Many years ago I built the Maplin Millenium stereo kit using one power supply section which sits left side. It sounded great but I put it in storage very quickly as it had a fairly loud buzz, not from the speakers, but from itself. During the silence between tracks, I could hear the thing from a few metres away.
I would now like to reinstate it and intend to part dismantle it and pretty the casework and upgrade some caps and wiring. I tried it briefly and it still works the same.
Any advise on the hum/buzz would be greatly appreciated.
Could be. I still have mine, although built up in different chassis and with a different mains transformer and valve rectification.
http://www.diyaudio.com/forums/tubes-valves/71300-photo-gallery-501.html#post3463034
One thing I remember was that the assembly instructions specified that only one screw through the transformers should contact both sides of the transformer. They put fibre washers under the other three screw heads. I'd also just check that the mains transformer doesn't have any obviously loose laminations.
If the rest of the amplifier still works well and you're sure that the hum is mechanical in origin, then it's hard to know what else to suggest.
Sure to be from the mains transformer.
As you describe it as a 'buzz', it could also be the transformer end bell (metal cover) vibrating against the core.
Why not remove the mounting bolts and end bell and rest the transformer on the chassis on four thin pieces of cardboard, then try it carefully. If it is still buzzing the transformer is faulty.
If it is improved, try fitting fiber or rubber washers between the transformer and chassis and between the transformer and end bell.
From memory the transformer is only just up to the job (it was up-rated in later years).
As you describe it as a 'buzz', it could also be the transformer end bell (metal cover) vibrating against the core.
Why not remove the mounting bolts and end bell and rest the transformer on the chassis on four thin pieces of cardboard, then try it carefully. If it is still buzzing the transformer is faulty.
If it is improved, try fitting fiber or rubber washers between the transformer and chassis and between the transformer and end bell.
From memory the transformer is only just up to the job (it was up-rated in later years).
Thanks for the replies/ advice. I will start on it shortly and check the 3 fibre washer situation and see if there is anything loose, etc. Let you know how it's going.
It is possibly dc offset on the mains causing transformer to buzz.
You could try a mains dc blocker circuit.
You could try a mains dc blocker circuit.
It was the fibre washers in the wrong place. All good after swapping to match the instruction manual. Thanks all.