Hi, I have a set of PSB bookshelf speakers with subwoofer. The subwoofer is the Alpha Subzero1 (pictured).
The subwoofer is not working at all so I removed the power supply / amplifier board from the unit and discovered several destroyed components where the red oval is (pictured):
The components appear to be 1W resistor, a couple Tantalum capacitors and a couple of power diodes. The damage has extended to the PCB where a copper trace in that area of the board has lifted.
My question is whether or not I should try to repair this board or just abandon the idea and buy a new subwoofer? Thanks for your thoughts.
The subwoofer is not working at all so I removed the power supply / amplifier board from the unit and discovered several destroyed components where the red oval is (pictured):
The components appear to be 1W resistor, a couple Tantalum capacitors and a couple of power diodes. The damage has extended to the PCB where a copper trace in that area of the board has lifted.
My question is whether or not I should try to repair this board or just abandon the idea and buy a new subwoofer? Thanks for your thoughts.
Hi, and welcome to the forum!
i can't say what has caused these components to fry, but I can give your thread a bump!
i can't say what has caused these components to fry, but I can give your thread a bump!
And I'd bump that subwoofer into the trashcan.
High failure rate SMPS power supplies by china.
The Polk subs also are made like crap.
Welcome to the new world of manufacturing junk.
I would agree, robmack, that the board is not worth fixing - although I would have broken the news more gently. 😉
I had one recently with a dead switch mode PSU. No schematic, I wasnt about put in the time to reverse engineer, so I lost all hope.
One would think they'd make it law to have the information freely available to repair. I remember back when you'd get the schematic pasted to the bottom plate. Or a little booklet inside, like the GE uWave I went into recently. Alas, if it exists, it's just another channel for cash flow to someone. No wonder so much hits the garbage can...
One would think they'd make it law to have the information freely available to repair. I remember back when you'd get the schematic pasted to the bottom plate. Or a little booklet inside, like the GE uWave I went into recently. Alas, if it exists, it's just another channel for cash flow to someone. No wonder so much hits the garbage can...
I'm known for being blunt, yes.
My customers through the years actually appreciated that.
This is good and honest feedback. I'm also peeved that there are no service manuals or schematics for this speaker to be found because I could fix it if they were available. I guess I'm in the market for a new powered subwoofer. Maybe I can recycle this as a passive subwoofer, who knows.
For me, it has nothing to do with a cheap "Chinese SMPS" and more to do with the fact it's the lowest end PSB sub they ever made. Even if it was a 5 minute 5$ repair, I'd just take the driver out and sell it. You could also just turn it into a passive sub if you have another amplifier already.
The trouble with these 'toss away' junky things is the cheapening caused by those lousy SMPS power supplies.
I've seen plenty of them come across my service bench at the shop - all brands.
Initially, they used a linear power supply before the cheapening started.
Those linear (traditional power transformer) supplies cost more, but the reliability and service life are much better.
A relatively expensive Polk sub, (popular brand) lasted 2 years and crapped out. - SMPS failure.
So, I replaced the whole plate amp with a linear-powered one.
It's been working fine for years now, the customer is happy.
Of course, I had to do some minor modifying - opening up the mounting hole.
See photos...
Look at the price point between those two devices though. Nevermind the extra carbon emissions from shipping a transformer across the planet.
Also looking by it, the Polk is class D so it doesn't need heatsinks - it's not that they left them out because they we're cheap.
My subwoofer set up cost me about 400$. Yorkville AP1200 bridges for 8R - 950WRMS powering a 15" passive car sub and driven by a Behringer CX2310 crossover set to 10Hz... Works better than any powered sub I've seen anywhere near that price point.
The Subwoofer the OP is asking about sells for about 100$CAD on the used market.
FYI The SMPS in my computer has a 12 year warranty. Nothing wrong with SMPS if you don't make a cheap piece of trash.
Also looking by it, the Polk is class D so it doesn't need heatsinks - it's not that they left them out because they we're cheap.
My subwoofer set up cost me about 400$. Yorkville AP1200 bridges for 8R - 950WRMS powering a 15" passive car sub and driven by a Behringer CX2310 crossover set to 10Hz... Works better than any powered sub I've seen anywhere near that price point.
The Subwoofer the OP is asking about sells for about 100$CAD on the used market.
FYI The SMPS in my computer has a 12 year warranty. Nothing wrong with SMPS if you don't make a cheap piece of trash.
Last edited:
you can toss that board and get one of this
https://www.parts-express.com/Dayton-Audio-SA70-70W-Subwoofer-Amplifier-300-784?quantity=1
and if you want more control over your DIY repair
you can get one of the new smallish class D amps
like this
https://www.parts-express.com/TDA7492-Digital-Audio-Amplifier-Board-2x50W-320-606?quantity=1
https://www.parts-express.com/24-VD...pply-with-2.5-x-5.5mm-Plug-120-055?quantity=1
then you just need to add your attenuation for volume control and maybe some low pass filter
ohhh, just noticed that your sub power 2 satellite speakers, kind of the Klipsh promedia 2.1
so you need a 2.1 amp board like this, for 40 bucks is a no brainer
https://www.parts-express.com/TPS31...-with-Filter-and-Volume-Co-320-635?quantity=1
and it comes with BT lol
- 12 to 24 VDC for versatility
- DC power jack, 3.5 mm Aux-in jack, and Phoenix speaker connectors for quick hookup
- Built-in master volume, treble, satellite volume, subwoofer volume, and low-pass filter potentiometers for sound customization
- Pre-assembled and pre-tested for easy project integration
- Class D efficiency and wireless 5.0 Bluetooth in one compact size board
- Easily switch between Bluetooth and line-in source by pushing and holding in the master volume control for three seconds
- 6 dB drop/octave at 150 Hz high pass filter switch, protects the satellite speakers
modify the amp board removing the pots and adding some wire to mount the pots on your front sub face and position the amp board somewhere inside the other was. i think that could be a fun new years project 😀
Best
Max,
Last edited:
I've got a 12" Velodyne that needs a new home. It's got an iron transformer PSU. Trouble is, it'd be super difficult to design a package for and ship successfully. Especially when I know every worker who touched it would "hate" it and handle it accordingly...
Imagine a place where you can leave your double bay garage door WFO all night long, multiple times - and everythings still there in the morning? Must be because we dont own anything worth stealing... "It's all crap Shifty; let's get out of here!"
I have decided to replace the blown electronics with a full range 100W miniature mono amp from Amazon: Nobsound 100W TPA3116D2 Amplifier Full Frequency Mono Channel Digital Power Amp Board
I'll change the 3.5mm phono input into a single RCA that can accept the subwoofer LFE output from my receiver. I have a spare Dell laptop power supply to give it juice. I've borrowed similar parts from a friend and tested the setup in practice. It works and sounds nice.
I'll change the 3.5mm phono input into a single RCA that can accept the subwoofer LFE output from my receiver. I have a spare Dell laptop power supply to give it juice. I've borrowed similar parts from a friend and tested the setup in practice. It works and sounds nice.
This looks to be a cheaper, better option: https://www.amazon.ca/TPA3116D2-Amplifier-Channel-Digital-Speakers/dp/B07K227MBR/
I was reading other threads were people complain about the sound of the really "bargain" class D little boards, and that is perfectly understandable, those designs use very cheapo components and most of the time have missing proper filtering like chokes and stuff in the board, you need to spend some more to get something that will please you ear ,i recommend this ice power modules, i have seen a couple of models and they sound great
this is an example of the ice modules, they offer several wattages and channels.
Best.
Max.
https://www.parts-express.com/ICEpo...wer-Supply-Module-1-x-200W-326-208?quantity=1
this is an example of the ice modules, they offer several wattages and channels.
Best.
Max.
https://www.parts-express.com/ICEpo...wer-Supply-Module-1-x-200W-326-208?quantity=1