Ferranti A1016 bluetooth project - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

coopzone · 10th Jul 2018, 8:30 pm

You could maybe use two capacitors, one from the -ve bluetooth to chassis and the other in the audio output from bluetooth. In the same vane as live chassis radios used caps to isolate the PU input.

May be worth an investigation.

Coop

coopzone · 10th Jul 2018, 8:35 pm

As a comment on your first post, mains hum. I had one of these sets and the mains hum proved to be magnetic interference from the mains transformer to the output transformer. Even without the rectifier valve in place (no HT) it still used to hum!

In the end i replaced the steel screws on the chassis mounting for the mains transformer with brass ones and used plastic strips instead of the metal spacers, it helped but never totally got rid of the hum.

Coop

egerton · 11th Jul 2018, 9:47 am

Thanks for the info. I had assumed it was the smoothing caps so removing the rectifier is a quick check to do see if my set is effected by hum as yours was. Paul

egerton · 21st Jul 2018, 6:17 pm

I am giving this set a good clean and thinking about replacing the Hunts caps. I've got the BT conversion working well and will install under the chassis, loads of room and cool down there. Before II do this now is the time to replace the small beige Hunts on the chassis and a large black one (2uF 'Metallised' 150V on the speaker for tweeter filter), advice on this forum suggests this is wise. When I was taking the chassis out and cleaning the facia I took off the magic eye EM84 and it was stuck fast in it's clamp. I coaxed it out very carefully and wondered if I was going to regret this, but I did not break it. It seems to have what looks like melted plastic strips stuck to the glass envelope. This must have been high melting point plastic cushioning inside the clamp. Does anyone know what I should use to replace this?
Thanks - Paul

10th Jul 2018, 8:30 pm	#41
coopzone Hexode Join Date: Jan 2018 Location: Cannock, Staffordshire, UK. Posts: 268	Re: Ferranti A1016 bluetooth project You could maybe use two capacitors, one from the -ve bluetooth to chassis and the other in the audio output from bluetooth. In the same vane as live chassis radios used caps to isolate the PU input. May be worth an investigation. Coop

10th Jul 2018, 8:35 pm	#42
coopzone Hexode Join Date: Jan 2018 Location: Cannock, Staffordshire, UK. Posts: 268	Re: Ferranti A1016 bluetooth project As a comment on your first post, mains hum. I had one of these sets and the mains hum proved to be magnetic interference from the mains transformer to the output transformer. Even without the rectifier valve in place (no HT) it still used to hum! In the end i replaced the steel screws on the chassis mounting for the mains transformer with brass ones and used plastic strips instead of the metal spacers, it helped but never totally got rid of the hum. Coop

11th Jul 2018, 9:47 am	#43
egerton Pentode Join Date: May 2018 Location: Beverley, East Riding Posts: 110	Re: Ferranti A1016 bluetooth project Thanks for the info. I had assumed it was the smoothing caps so removing the rectifier is a quick check to do see if my set is effected by hum as yours was. Paul

21st Jul 2018, 6:17 pm	#44
egerton Pentode Join Date: May 2018 Location: Beverley, East Riding Posts: 110	Re: Ferranti A1016 bluetooth project I am giving this set a good clean and thinking about replacing the Hunts caps. I've got the BT conversion working well and will install under the chassis, loads of room and cool down there. Before II do this now is the time to replace the small beige Hunts on the chassis and a large black one (2uF 'Metallised' 150V on the speaker for tweeter filter), advice on this forum suggests this is wise. When I was taking the chassis out and cleaning the facia I took off the magic eye EM84 and it was stuck fast in it's clamp. I coaxed it out very carefully and wondered if I was going to regret this, but I did not break it. It seems to have what looks like melted plastic strips stuck to the glass envelope. This must have been high melting point plastic cushioning inside the clamp. Does anyone know what I should use to replace this? Thanks - Paul