Harman Kardon Soundsticks III Bad subwoofer, low bass

[viewfindr]

I have a pair of rarely used computer speakers. Recently, I noticed that the subwoofer was barely working. Both satellites are still good, but even when turned up all the way, the subwoofer is extremely weak and produces almost no bass. It definitely still outputs a little bit on the deepest notes, but is far from what it should be.

I took it apart, and the subwoofer driver measures about 17 ohms on a multimeter. I couldn't get figure out how to get the board out, but attached some photos (cables attached are affixed to the housing). The caps look good to me (no bulging or leaking), any ideas what could be the culprit?

Here's a photo of the circuit board I found online for reference: https://www.petervis.com/speakers/so...uit-board.html

I think this is the schematic of a similar model: https://servicemanuals.us/harman-kar...5.html?start=9

[stj]

Re: Harman Kardon Soundsticks III Bad subwoofer, low bass

first thing on those is the caps are shit.
re-cap it with panasonic FR.

second, they can blow the power amp chip if the caps get bad enough.
third, the caps can also go in the psu brick - which is under-powered to begin with.
infact from your description i would look in the psu first!!

is it the USB model or the one with a pair of jack plugs??

[viewfindr]

Re: Harman Kardon Soundsticks III Bad subwoofer, low bass

first thing on those is the caps are shit.
re-cap it with panasonic FR.

second, they can blow the power amp chip if the caps get bad enough.
third, the caps can also go in the psu brick - which is under-powered to begin with.
infact from your description i would look in the psu first!!

is it the USB model or the one with a pair of jack plugs??

Interesting thought on the PSU, I'll take a look there and see if anything looks off. I'm assuming that the caps fail, it should be visually obvious?

This is the model with a single 3.5mm out, so jack plugs.

[stj]

Re: Harman Kardon Soundsticks III Bad subwoofer, low bass

the psu's can blow caps - and often even have burned looking boards because they get so hot!!