Altec Lansing ACS400 (Desk top stereo/Dolby Digital speaker & Sub, circa 1995) [right speaker] does not work; how can I fix it?

It is a DIN plug, just count the pins, '5 pin DIN', '7 pin DIN'.

Altec Lansing Speakers are not worth repairing.

This says it is a 7 pin DIN.
https://assets.hardwarezone.com/2009/reviews/others/acs400/acs400.htm

..

the red light is power indicator

3 causes. generic. then real.
60Hz hum/.

1. the PSU inside the SUB is bad, as in bad CAP's inside.
2. input cables to it bad, shields broken (coax cables)
3. bad source signals from what ever is connect to the sub.

in this case (no pun) the main case is the SUB and the PSU is inside the sub
so sub bad. or
test it with no L/R speakers yet , it still hums or is dead well the main unit is bad and needs service. OR

the main has cable from PC to MAIN SUB case.
IF this cable is bad, is first check.but that would make L or R fail too.
a bad shield will not only effect the sub speaker, (hum)
the PC end is only 3 conductors L and R and shield. some are sold double shielded, and are prime to own..

try a new 3.5mm phone patch cable, just in case his fixes it cheap.
or the 2 cable ends to PC , phone plugs are lose
or dipped in spilled drinks gunk.

or PC is bad , ( try other sources , PC, phones, or mp3 /dvd players.)
the PC bad would effect R or L too. IMO

If your subwoofer does not work on your altec lansing speakers,
more than likely you blew the subwoofer amplifier board.
I have an ADA-885 system and bought it brand new back in
November 2000 and has been flawlessly operating great up
until this past month when my subwoofer went out but my
"satellite" speakers kept working. After disassembling the
subwoofer box I first noticed that the subwoofer amplifier
board is seperate from the rest of the grouped boards for
the dolby and satellite speakers. The subwoofer box is
designed to use the air from the subwoofer to actually
cool the amplifier boards inside the unit, great feature
until your subwoofer goes out, that is when your main
amp will more than likely fail soon after the sub amp
fails, as it uses the air from the subwoofer to keep the
amps cool. I know this might be an older post but
hopefully I can put it in the right category to hopefully
be able to help someone out in the future.

You can test the ohms of the speaker with a multi
tester. It's a dual voice coil speaker, 6 ohms each.

Well my system is broke and needs another
subwoofer amplifier board so if anybody reads
this and has this subwoofer, I need my sub amp
fixed ! or if you have the subwoofer unit maybe
and nothing else to go with it but the subwoofer
lights up, give me a jingle, I'd buy it from you !!

Sub woofers have small amplifiers , not transformers. The amplifier is removable and replaceable. The The overall size and the output wattage are the spec's you need . The output wattage is on the label which is attached somewhere on the speaker. You do NOT need to replace the amp with the Altec Lansing brand. Have you contacted Altec Lansing to purchase a replacement Amp? That's where I would start. If they cannot help you I would Google replacement amp sub-woofer, Altec Lansing model MX5021.
good luck

Philips DVP 3256 has 6 outputs which takes in RCA connectors
Altec lansing VS3251 has 3 STEREO outputs.
Buy 3 nos of STEREO (female) to RCA (male) cables
1. Connect the Altec's green wire to first stereo-to-RCA cable. RCA ends to DVP 3256's Front left and Front right
2. Connect the Altec's black wire to second stereo-to-RCA cable. RCA ends to DVP 3256's Rear left and Rear right
3. Connect the Altec's orange wire to third stereo-to-RCA cable. RCA ends to DVP 3256's Centre/Sub woofer. Interchange RCA ends if the Subwoofer sounds dull.

Good Luck

red-positive . blue-negative and if another colour mostly brown-Earth.

I had the same problem. One day I heard two pops and the speaker, including the power light, were dead. Neither Dell nor Altec Lansing support them. They're throw-aways, unless you know a genius electronics technician.

Looking at the manual http://www.alteclansing.com/downloads/EUR/VS2121%20manual.pdf page 3 of the pdf says Connect the lime green 3.5mm stereo cable (hardwired into the right satellite) to the lime green input labeled ?FRONT? on your sound card. So your right speaker should have a cable with a green end that plugs into your standard audio out jack If you have multiple outputs and don't know which you are set up for, then turn the speakers on and up, put a long song on, and plug that green wire into every jack on the PC! If you've got no other issues you'll hear something! Good Luck

hi there are fast checkings for you: Quick Connect Card http://www.alteclansing.com/downloads/641QCC.pdf manual: http://www.alteclansing.com/downloads/641_MAN.pdf is the system working fine exept the sub? my guess: the headphone jack works fine then the speakears are too if soo then the sub amp is bad or some connection is torn try opening the sub and see if everything is hooked right and if soo then the amp is the problem every electronics shop can fix this good luck