Trio R-1000 mains hum - UK Vintage Radio Repair and Restoration Discussion Forum

Tea_Bot · 4th Sep 2021, 8:59 pm

Hello all,

My Trio R-1000 has a noticeable 100hz hum on the audio. I have changed the capacitors in the psu but these checked out ok with ESR meter.
The audio starts to breakdown and distort after the radio is fully warmed up.
Audio stage capacitors maybe?
Any pointers please.

Regards
Teabot

Tea_Bot · 5th Sep 2021, 12:00 pm

Turns out the radio had been modified with some kind of noise blanker or audio filter addition. Hum gone now removed , must have added a ground loop into the audio chain.

Tea_Bot · 5th Sep 2021, 12:26 pm

Its a FM demod board, been informed. Shame its adding a ground loop.

4th Sep 2021, 8:59 pm	#1
Tea_Bot Triode Join Date: Nov 2018 Location: Bridgend, Mid Glamorgan, Wales, UK. Posts: 16	Trio R-1000 mains hum Hello all, My Trio R-1000 has a noticeable 100hz hum on the audio. I have changed the capacitors in the psu but these checked out ok with ESR meter. The audio starts to breakdown and distort after the radio is fully warmed up. Audio stage capacitors maybe? Any pointers please. Regards Teabot

5th Sep 2021, 12:00 pm	#2
Tea_Bot Triode Join Date: Nov 2018 Location: Bridgend, Mid Glamorgan, Wales, UK. Posts: 16	Re: Trio R-1000 mains hum Turns out the radio had been modified with some kind of noise blanker or audio filter addition. Hum gone now removed , must have added a ground loop into the audio chain. Attached Thumbnails

5th Sep 2021, 12:26 pm	#3
Tea_Bot Triode Join Date: Nov 2018 Location: Bridgend, Mid Glamorgan, Wales, UK. Posts: 16	Re: Trio R-1000 mains hum Its a FM demod board, been informed. Shame its adding a ground loop.