29-05-2021, 01:54 PM
Looks like I am back to square one!
Thanks to help of Trevor and Andy, the amp is working reasonably well. I decided to replace the switch on the volume control to try and overcome the mains hum that is still there. Initially I thought it was an old valve amp with a natural level of hum but in using it I really do think that its very much annoying and needs to be rectified. The switch is in and working BUT the mains hum is still there and also the speaker 'pop' when turning off has returned (I have removed the mains cap as I thought I wouldn't need it with the switch separated from the volume control).
As it was indicated before, and I big learning curve for me, is using my oscilloscope to find the source of the hum. I am assuming that this must be caused by a ground loop(?).
I must admit I am no expert at all in using and oscilloscope or where on the circuit to take readings. I am concerned that about connecting a probe to ground just in case I short the circuit due to the earth design as it appears to run to earth at the opposite end of the circuit board from where it initially starts which I don't believe is a great approach (certainly from videos etc I have seen).
Best Regards
Rob
Thanks to help of Trevor and Andy, the amp is working reasonably well. I decided to replace the switch on the volume control to try and overcome the mains hum that is still there. Initially I thought it was an old valve amp with a natural level of hum but in using it I really do think that its very much annoying and needs to be rectified. The switch is in and working BUT the mains hum is still there and also the speaker 'pop' when turning off has returned (I have removed the mains cap as I thought I wouldn't need it with the switch separated from the volume control).
As it was indicated before, and I big learning curve for me, is using my oscilloscope to find the source of the hum. I am assuming that this must be caused by a ground loop(?).
I must admit I am no expert at all in using and oscilloscope or where on the circuit to take readings. I am concerned that about connecting a probe to ground just in case I short the circuit due to the earth design as it appears to run to earth at the opposite end of the circuit board from where it initially starts which I don't believe is a great approach (certainly from videos etc I have seen).
Best Regards
Rob
if all else fails...read the instructions!
