Plenty of consumer goods, from passenger vehicles to toys to electronics, get tossed out prematurely for all kinds of reasons. Repairable damage, market trends, planned obsolescence, and bad design can all lead to an early sunset on something that might still have some useful life in it. This was certainly the case for a sound system that [Bill] found — despite a set of good speakers, the poor design of the hardware combined with some damage was enough for the owner to toss it. But [Bill] took up the challenge to get it back in working order again.
The main problem with this unit is that of design. It relies on a remote control to turn it on and operate everything, and if that breaks or is lost, the entire unit won’t even power on. Tracing the remote back to the control board reveals a 15-pin connector, and some other audio sleuths online have a few ways of using this port to control the system without the remote.
[Bill] found a few mistakes that needed to be corrected, and was eventually able to get an ESP8266 (and eventually an ESP32) to control the unit thanks largely to the fact that it communicates using a slightly modified I2C protocol.
There were a few pieces of physical damage to correct, too. First, the AC power cable had been cut off which was simple enough to replace, but [Bill] also found that a power connector inside the unit was loose as well. With that taken care of he has a perfectly functional and remarkably inexpensive sound system ready for movies or music. There are some other options available for getting a set of speakers blasting tunes again as well, like building the amplifier for them from scratch from the get-go.
recently a friend gave me some cheap (Behringer) studio monitors. told me he was “hooking them up one day and smoke came out”. he was gonna trash them but he thought I may want to try repairing them
I found the usual failure inside. the only psu capacitor inside was swollen and the two Amps (tpa3116d2 and tpa3130) bot caught fire. I suspect what happened was that this smoothing capacitor didn’t smooth and the peak voltage from the switcher exceeded the absolute maximum rating of the amps, and they will just blow up.
the board was charred beyond repair. when de soldering what was left of the amps, some pins had even welded to the traces..the board was gone beyond repair. it was even gouged by the flash in a couple of places.
I ended up getting two cheap amp boards with those chips and stuffed them inside the cabinet. I used some thin wire to tap the signal out of the traces left on the board and they work now.
the sound is… not great. they need a lot of eq to sound nice. I’m not sure if they sound like this from the factory, or if there is some passive eq going on in the signal path and it’s interacting with the input of my new PCBs. but they are ok nevertheless
I’m thinking of replacing the low ESR smps capacitor with a solid polymer one for longer life. it seems like it’s under a lot of ESR stress and that’s why it failed.
regardless, it feels great to save a device like this from the bin
Possible that the monitors are flat response, so they’re designed to give you a true sound as opposed to a pleasing sound. I’ve had Behringer speakers and they were okay, but if they’re recording monitors they could have a flat EQ to aid in mixing.
I was told that you should never buy studio monitors if you don’t need their specific sound, as they sound flat and dull etc. I wouldn’t know, but this may add another data point to my anecdote store.
Buy yeah at least you didn’t buy it, and could fix it! Win.
This is mostly true. A lot of commercial offerings are tuned to be “peaky” in the lows and highs. Beats headphones are a good example.
I prefer the flat sound of a studio monitor myself…maybe I got tired of all the boomy car audio I did in the 90s….or maybe it was the time I spent as a hobbyist mixing/producing music.
Nice effort. Lots of these were sold under the Logitec brand including a 2.1 version. For power efficiency when silent, any need or benefit to detecting lack of audio activity and powering down? Similarly, detecting audio and turning everything back on?
When the “mains” are this small monitoring is a joke as lower mids are coming out of somewhere else than the soundstage. Single woofer is not the same as a subwoofer. If used in the corners of a room part of a male voice would come from the big box not the soundstage. These are just “computer desk speakers” in 5 channel limited range and a single woofer, but they’re working again. I wonder how much of the crossover was reconstructed or lost, there could be bass in those little speakers and break them.