UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Grundig TK20 and Truvox R82. Help Required Please.

TerryB44 · 7th Jan 2021, 3:23 pm

[Quote Mike]
IYou should also try (perhaps before you do anything else) putting a short circuit across the playback head connections (just disconnecting the head as you’ve said you’ve done won’t prove anything - an open-circuit playback input will pick up hum in a very high sensitivity playback amplifier with AC magnetic fields nearby). If the hum vanishes when you short circuit the head then you have probably got either an open-circuit head or a hum-loop in the grounding system.

[/I]

Mike[/QUOTE]

I have short circuited the playback head and the hum goes away. The playback head does play but only at very low volume.

7th Jan 2021, 3:23 pm	#85
TerryB44 Pentode Join Date: Mar 2013 Location: Liverpool Posts: 102	Re: Grundig TK20 and Truvox R82. Help Required Please. [Quote Mike] IYou should also try (perhaps before you do anything else) putting a short circuit across the playback head connections (just disconnecting the head as you’ve said you’ve done won’t prove anything - an open-circuit playback input will pick up hum in a very high sensitivity playback amplifier with AC magnetic fields nearby). If the hum vanishes when you short circuit the head then you have probably got either an open-circuit head or a hum-loop in the grounding system. [/I] Mike[/QUOTE] I have short circuited the playback head and the hum goes away. The playback head does play but only at very low volume.