Denon DHT-S514 plop and or hissing noise 🔉
A friend recently dropped a Denon DHT-S514 soundbar as it produced loud plopping sounds (the one we all know from our childhoods when DC voltage made its way to the speakers). 🔉
I did not expect an easy fix and it took me a couple of attempts to get this repaired. Per the link below it was worth checking DC blocking caps between the TL074C and the TPA 3118.
When the soundbar is running for some time 🥵 (mostly just minutes) the sound drops with a loud plop, taking some seconds to recover before the sound comes back. As those plops are usually a DC thing, the suggestion made absolutely sense.
Measuring the caps while the device was off did not show any anomalies.
While the soundbar was running, I did measure the caps and there was nothing suspicious. However, when measuring the caps while the device was running it turns out when:
- measuring C236 or C231 the sound has a disturbing hissing added to it (what we read in some forums),
- measuring C284 or C275 we immediately get the 'plop'.
This is nothing to worry about regarding defects but at least show, where the noises are produced. Since I assume this is a stress under heat thing, a quick test with the icing spray proves: as soon as the caps get cooled down, the plop disappears.
That said, let's replace C204, C217, C231, C236, C247, C260, C275 and C284. It looks like 16V/10uF might be an appropriate choice by design, I went for 50V/1uF for better resilience.
The soldering job is not super clean 👨🏼🔬 but does the trick:
Giving it some hours of operation shows: this repair did the trick! 💪
Reference
https://www.hexnut.net/2017/06/denon-dht-t100-bad-caps-ceramic-caps.html