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Xyience · 30th Jan 2021, 1:44 pm

My TK20 is experiencing an audio issue which I have described as motorboating in the thread title, but the truth is I do not know the name or source of the problem.

Symptoms: Audio output through the built-in speaker is clean and distortion-free until I set the volume control past a certain volume. At that point the playback breaks up into a low-frequency, loud "duh duh duh duh" where the music can still just about be heard, albeit chopped up.
If I back off the volume the clean sound returns.
The volume level at which the oscillations start gets lower and lower over the course of a listening session.
Letting the deck cool down seem to reset the point of oscillation on the vol. control.

What I have 'fixed' so far: The deck was untouched when I received it. Sound was OK for a few weeks and then got quieter and more distorted. I then replaced all of the Wima toffee caps which all had surface crazing. The sound came back.
I have not touched any of the electrolytics or the rectifier.

Is this motorboating and how do I fix it?

30th Jan 2021, 1:44 pm	#1
Xyience Tetrode Join Date: Dec 2020 Location: Chelmsford, Essex, UK Posts: 69	Grundig TK20 'motorboating'? My TK20 is experiencing an audio issue which I have described as motorboating in the thread title, but the truth is I do not know the name or source of the problem. Symptoms: Audio output through the built-in speaker is clean and distortion-free until I set the volume control past a certain volume. At that point the playback breaks up into a low-frequency, loud "duh duh duh duh" where the music can still just about be heard, albeit chopped up. If I back off the volume the clean sound returns. The volume level at which the oscillations start gets lower and lower over the course of a listening session. Letting the deck cool down seem to reset the point of oscillation on the vol. control. What I have 'fixed' so far: The deck was untouched when I received it. Sound was OK for a few weeks and then got quieter and more distorted. I then replaced all of the Wima toffee caps which all had surface crazing. The sound came back. I have not touched any of the electrolytics or the rectifier. Is this motorboating and how do I fix it?