We won’t repair that. Just throw it in the trash?

PreSonus cannot repair, supply spare parts, issue schematics or service manuals for the PreSonus Eris 3.5BT speakers I bought 3 years ago. "PreSonus would like to apologise for any inconvenience caused" is written at the end of the message where they basically tell me to throw away a pair of speakers. That is indeed inconvenient?

When I purchased a pair of PreSonus studio monitors, I obviously expected them to be of great quality. Our old B&W speakers have lasted 30+ years and I honestly thought that PreSonus was of similar quality. In terms of audio quality, this was a good upgrade to an 2:1 setup from Logitech that I've had for 10+ years. I also have a matching PreSonus Sub8 in this setup, so alltogether it's a $400 audio system. Not cheap, but also not too expensive. I primarily use the connected PC for listening to music while I work on my Mac, with some additonal audio/video work and gaming. I just want good sound with proper bass when I'm working.

After three years of use, the speakers simply died. Since I design electronics on a daily basis, I didn't have a problem opening them and doing some quick diagnosis. It was the 230V AC power stage that was defect. I measured it out and it was simply dead. No visible damage. I better contact PreSonus to hear what support they can offer? Maybe I could just buy new electronics and do a quick replacement?

PreSonus sells software & hardware geared towards the semi-pro market, so you'd expect them to be quite good when it comes to support? After all - they must want customers to keep buying their products? They offer a ticket-based support system that works fine, but based on the reply I got it looks to be a very easy job to work there?

You basically just have to check if the limited warranty has passed and then paste this reply to all customers? They're not saying it explicitly, but they are still telling me to just throw the speakers in the bin? They won't offer any kind of support, parts or even help in the form of a schematic? Electronics like this should last more than 3 years, but when they break - any good firm should offer advice for how to get it repaired? PreSonus don't. 

How to NOT throw perfectly good speakers

So here I am. I have a proper subwoofer and no primary speakers. Or wait? The speakers themselves are perfectly fine. PreSonus don't prohibit you from your RightToRepair. They just make it difficult to do so?

It's just the electronics driving them that are defect so I'll just rip out the amplifier and replace it with a new one! Tearing out the old electronics showed one of the reasons that PreSonus don't offer repairs or support. They've basically built the speakers so they are hard to service. Getting into the case is easy. Just remove screws and you have access. Getting to the electronics is the hard part. Due to the excessive amount of glue and glued foam, the only way you can take this apart is using a knife.

There's absolutely no reason for these foam pads to be glued both to the PCB and the case. Gluing to only one side would allow easy access and a way to replace defect electronics. It's just a very stupid choice that enforces planned obsolescence? After getting the foam apart, it was just a matter of cutting the right cables. The only thing I could reuse in a simple way was the OnOff switch at the front and the only part I found sensible to salvage was the heatsink.

To get into the slave speaker, pull carefully on the entire front plastic piece. Be sure to pull evenly on all sides, so you don't break the plastic pins that hold the front in place. Unscrew the main speaker and you have access to the internals. All I did here was to cut the cables and solder in replacements. Could have just used Wago's here for simplicity.

The original electronics from PreSonus are based around the ST TDA7265. There's no way for me to revive that unless I spend an insane amount of time. I dug around my random parts bin and found an amp based on the TI TPA3116D2 that I bought for research some time ago. The PCB has 3 of these chips built in so it has two chips with bridged outputs for driving bass and one for treble & midrange. This provides enough power to drive the entire system actually? The main difference is that this PCB had class D amps vs the single class AB from PreSonus, so it's kind of overkill for the purpose but it will certainly do the job.

I test fitted the electronics and hooked it up. The audio quality was decent. I first tried using the bass outputs on the new board to drive the big element, but that left a complete lack of mid-range. Disassembling the slave-speaker revealed that there's no active splitting of the audio between the tweeter and push/pull speaker, so only the original wire is needed between the two speakers.

The PCB has an adjustable cutoff knob that will decide what goes to mid/treble and bass outputs. This circuit isn't exactly HiFi quality, but for my purpose this is good enough. Given the extra bass outputs, this board even has the required power to drive the Eris Sub8 if that dies a similar premature death? Or I could drive one of the many transducers I have to properly shake the desk while I'm playing games? Just like the old one's, this board has bluetooth and it also adds an option to play from a memory stick? Not bad for a $35 replacement from Aliexpress?

After spending an hour in Fusion360, I had a model of the new backplate with a new name that reflects the new internals. 

Three test prints on my Prusa 3D printer later, I could assemble the entire setup. Turned out quite nice? The 3D Models can be found on Printables if you have a pair of unrepairable Presonus speakers.

Update 29 July 2024: I messages PreSonus support with a direct question if I should bin the speakers. Below is their reply. They're not saying it explicitly, but still saying that they won't offer anything in way of support. Shame. I'll buy some Genelec monitors the next time then.