I have an Almarro 318B. I have removed volume and input switching, using a Placette passive, and I have installed new coupling capacitors. I have a hum in the right channel only. Not affected by volume or tube switching. I have carefully looked at the point to point wiring, and nothing seems to be remiss. I also tried shielding the right channel because it is near the transformer, but with no effect. Any ideas?
When you removed the Volume Control and Input Switching you most likely either:
1) left a shield disconnected
OR
2) introduced an extra shield to ground connection unitentionally, thus creating a ground loop
The place this often happens is right at the input connector, The connectors themselves should have their "ground" sides insulated from chassis a be connected to the amps 0V point via the shield of the lead from that connector.
A few things for you to check.
Cheers,
Ian
1) left a shield disconnected
OR
2) introduced an extra shield to ground connection unitentionally, thus creating a ground loop
The place this often happens is right at the input connector, The connectors themselves should have their "ground" sides insulated from chassis a be connected to the amps 0V point via the shield of the lead from that connector.
A few things for you to check.
Cheers,
Ian
Thanks Ian. A ground loop is certainly lurking somewhere. My wiring looks correct, but I didn't think to check the insulation of my new phono plugs from chassis ground. I'll do that. If no luck, I'll disconnect the inputs at the tube sockets to isolate the ground loop, one stage at a time.
Regards,
Michael
Regards,
Michael
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.