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Is there a way to use the Altec Lansing VS4121 Subwoofer as a stand alone?
Normally these low end system components depend on each other and cannot be interchanged with components from other system. So if one of the components (subwoofer or right control satellite speaker) breaks or gets lost the whole system is unusable...I was in the same situation. Got a subwoofer from VS4121 without original satellite speakers. I acquired satellite speakers from Altec Lansing 251 which used same connectors but the internal wiring was different and incompatible. Speakers are also glued together so it is impossible to open without damaging it. Obviously there is no service documentation anywhere..But if you like electronics you can try to make something based on the information below:Altec Lansing VS4121 connector pinout:Take the male connector (from right satellite speaker) and number pins in first row from left to right as 1-3, pins in the second row as 4-7, pins in the bottom row as 8-9 and the circle enclosure as 0. Then:0 - Ground 1 - Speaker Right2 - Treble (seems just like voltage control but may need to be confirmed: Min=0V; Max=voltage from Volume control Pin 9)3 - Head Set Right4 - Bass signal (not sure what the exact original design is as I have not opened the speaker) But seems like they use 50K potentiometer and some sort of RC low pass filter configuration. When potentiometer is set to Min it is shorted with ground. When set to Max it is taking signal from Right and Left Head Set (pins 3 and 5) combined through some larger resistors and low pass filter. 5 - Headset Left 6 - Ground for Headset (grounds 0 and 6 seems to be connected in the subwofer but within the right satellite speaker they seem to be isolated with separate leads to sub)7 - Power ON/OFF. When OFF or headset jack plugged then 0V. When ON and headset jack unplugged then 5V8 - 5V Power in9 - Volume (min=0V; max=5V). It seems they use 50K potentiometer but probably anything >10k should work.At minimum for standalone subwoofer you will need to implement:- Power On/Off (switch between pins 8,7)- Volume control 50k potentiometer (probably anything between 10k and 50k will do) between pin 7 and 0 with variable output to pin 9- Bass control - join two resistors R (I used 7k) and call this join point A. Attach other ends of the resistors to pins 3 and 5 respectively. Attach 50k potentiometer (I used 10k) between point A and ground 0. Attach Variable pin of the potentiometer to pin 4 (Bass input signal). Attach capacitor C between Pin 4 and Ground pin 0 (I used Electrolytic 1uF with negative end to ground) . Resistor R and capacitor C should make simple passive low pass filter (Google for formula) that should short any frequency higher than 80-120Hz to ground and feed frequencies lower than 80-120Hz to pin 4.PS: I managed to hack 251 control satellite speaker to somewhat work with VS4121 Subwoofer but that is another subject. All electronic parts were salvaged from old broken TV so total cost was $0 but took several days of tinkering for speakers that I could buy used for $10-20 :)
My Altec Lansing VS412 subwoofer
It could be that the vibration from the unit has caused a solder joint to become loose. That would explain why it works sometimes. All you need to do is go inside with a small soldering iron and retouch any connections with it.
Altec Lansing VS4121, New Speakers, No Sound
If the speakers are brand new it makes me wonder how you know they worked fine in the States? I am also wondering how they were transported due to them probably being intolerant to extremes of temperature/humidity and probably vibration.
I am also wondering if you are using the correct supply voltage and type of supply.
If you are using the power adaptor supplied for use in the USA, it would probably be incompatible with your supply even though you are using a transformer.
If you are certain the speakers are in good order I suggest you obtain a power adaptor designed for your 220 volt 50Hz supply. I have browsed a little and cannot find a note of the power requirements for the integrated amplifier but this is presumably marked on the adaptor, the speaker or in the manual and so the power adaptor could be checked on and off load with a suitable voltmeter. I would be surprised to learn the supply is adequate
How to open the subwoofer housing to change the fuse
on the back unscrew all the screws (there should be 8 in the plastic square around the jacks... and then undo the four that are in the wooden back) then pull out the plastic square, it will take a decent amount of force, try prying with a flat head screw driver. Once you have that out, you should be able to access what you need inside.
Pop open the back side of the sub and see if the to connections are soldered firmly to the wires/drivers themselves & make sure your system is grounded meaning the 3 pronged plug has to have the 3 post still connected to the power cord. If its broken off as most people do it'll cause that feedback or dull hummmmm noise.
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