Limited volume on speakers. Worked well previously.

Guys,

In case my nickname does not show, this is treefarmer. I had the same problem and decided to fix it myself over this Christmas. I was successful, and here is what I found.

In my case, the problem lies with the volume control chip ( it has a voltage controlled amplifier, or VCA in it) on the main amplifier board. The voltage which controls the volume for all channels comes from the right front speaker. There is an issue with the I.C., in that it has some abnormal loading (leakage) of the volume control signal at the I.C. pin. You need about 5.2 volts for full volume output, and on my system, I can only get about 1 volt. You can find the IC data sheet (Mitsubishi M51132L) here:

datasheet.html">http://www.datasheetarchive.com/M51132L-datasheet.html

The parts inside the enclosure get quite hot under normal operation, and I would not be surprised if this I.C. has an issue with degradation under high temperature. Regardless of the problem, I managed to get the volume back with one simple fix.

If you can open up the right front speaker, place a 10 kohm resistor in parallel with R1, which should have three orange stripes, and one gold stripe. This fixed mine, but this might only be temporary, depending on how much worse the volume control I.C. becomes.

I did check out the power supply, including transformers and everything else, and they all look fine. It would surprise me if the transformer failed as has been posted in other forums. They should be able to survive higher temperatures than the other electronic components in the box, especially when most of them are consumer grade parts with a max temperature of 70 C. One thing of note is that turning off the right front speaker pretty much shuts off most of the quiescent current draw of the amplifier board. I found that with only the sub cabinet switch on, nothing gets warm. You won't see significant warming of the interior components until you turn on the right front speaker. However, then the inside of the sub enclosure gets pretty hot (too hot in my opinion) just sitting there with all the speakers powered up.

I would recommend at least turning off the Right Front speaker when the computer is powered down. More often if you are not listening to anything. I don't think you need to shut off the sub enclosure to keep things cool, but turning off everything ensures that the amp is not sitting there cooking itself. And, unless Altec has changed the design, I would bet new systems will fail in the same manner.

For what that's worth. Hopefully somebody will find this helpful

TF

We bought the ADA745 system with our Dell computer six years ago. The last few years the sound has faded down to nothing. Yesterday I started to look for something to identify the problem -- best suggestions were those above on FixYa. A sound card voltage problem -- ICM? -- was suggested; overheating was another possible problem. I started to see if I could rip the main volume adjustment (right, front) speaker apart to figure out where this one review said you had to stick in an electronic do-hickey (capacitor, resistor, transister, babysitter?) to get your tunes back -- welded shut, harder to enter than Ft. Knox. Like all things for American consumers, not intended for repair -- planned obselescence. I decided not to go there.

One recommendation above had a far more low-tech solution (just my speed): Plug the right front speaker plug into the subwoofer only part way. And hey, hey, I am hearing "Life in the Fast Lane" by the Eagles loud and clear even as I type this. Push it in, but not too far, wiggle to the right (oh just the woofer has volume), wiggle to left (heard the sound, but now it's gone), a little back to the right and pull it out a smidge and I'm good to go. Maybe, Monster Cable's 24k gold contacts ain't all hype...

Now, how do I fix the right rear speaker cord the dog chewed up (or was it the rabbit before he singed his whiskers chowing down on the washer's cord -- brought an electrician in to fix that one)?

I am experiencing what appears to be the same problem as Barjo (speakers at half volume). This is the second time I have experienced a speaker volume problem with my 3-year-old system. The first time was about a year ago after installing "City of Heros". The root cause of the first occurance was my son had turned down the audio within the game. After logging on to the game and re-setting the audio, the speaker volume returned to it's original full capability. This time I have logged on to all of my son's games and confirmed the audio settings are at max. Additionally, like Barjo, I have checked connections, fuses, scanned for viruses and spyware, installed updated drivers, performed Sound Blaster Live! Series diagnostics, checked audio settings of all media players and tweaked every audio-related setting I can find. Unfortunately nothing fixed the problem this time. I am beginning to think the sub-woofer amp or the sound card is the problem. However, before I replace the speakers or the sound card it would be helpful if someone can tell me how to confirm there is a problem with one of these components. Any helpful input would be appreciated. Thank you!

I have the same problem and also tried all of the above. I suspect there is likely a problem with the integrated amplifier in the sub-woofer, and not the PCI sound card. I'll be taking mine apart today to check some components. Two things to consider though; a) if you got yours as part of a system and it is under 3 years old, Altec Lansing offers warranty support and b)if it is the amp, you can pick up a new set of speakers for under $40. To check try plugging in to a Laptop if you have one. Good Luck.

After 16 years my Altec Lansing ADA745 speakers finally lost their volume and the sound was barely audible as described by others here. A few times it came back for a day or 2 but then would go back to low volume. After finding this post I disassembled the right speaker and shorted the red & yellow wires with a paper clip and full volume came back!

I noticed that when I removed the short the volume would continue to work correctly but only for a few minutes and then it would go low again. It seemed like the longer I left the short on the longer it worked when I removed it. Very strange... As a test I left the short in place for 2 hours and then took it off and the volume stayed loud for about 2 hours and then returned to low again.

Anyway I didn't want to leave a permanent short in place so I soldered a wire to both the red & yellow wires and ran the 2 wires out a small hole I drilled in the back of the speaker. Now I can short the volume as need to restore the volume.

Not an ideal solution but it gets the job done. Hope this helps others.

Had same problem with my ADA 745 sound system which had worked fine since 2002. To open right front speaker carefully pry-off metal grill to expose four screws and then support base to expose one more. Once these five screws are removed unit comes apart to expose IC board and R1 resistor. Found 10K Ohms 1/8 watt resistor at RadioShack for $1.47. After soldering 10k Ohms resistor in parallel to R1 sound system now works like new.

So I know this an old topic but I found the solution. The problem with the fading volume is within the power/volume control switch on the front right speaker. The yellow control wire, for whatever reason, had lost its function over time. If you disassemble that speaker to get to the circuit board you can test this by shorting the red and yellow prongs with a screwdriver or something else that wont shock you...
In the end I cut the yellow wire and removed the casing for the last 1/4 inch and shaved away a small portion of the red wire's casing to reveal the copper, but to leave the wire connected. Then I spliced the yellow wire onto the red power wire using electrical tape. You will lose the volume control function for your system (the speakers will always be on max), but you will still be able to turn the speakers on and off. I control the volume of the speaker system from my laptop so it's not a big deal. Cheers!

I had the same problem. It turned out to be the volume control speaker. I replaced that and speakers work full power again, no problems! I got the volume speaker on ebay.

Hey Everyone,

I got this problem recently. I have a subwoofer system. Speakers limited to half volume even when turned up to the max. I have a dell Dimension E520. I tried another set of subwoofer speakers and they had the same problem. The problem I think might be the computer and not the speakers but I don't know for sure. The speakers I have have a green single pin plug. The green port on the back of the Dell tower is part of 6 ports all grouped together. One of them is the microphone port. there are other ports and I put the green plug into these. I found that the black port (I don't know the technical name or term for this port) gave me a proper loud sound at max. If you have the same configuration I suggest you try this and hope it works. Music is the main reason I use my computer and I understand how annoying this problem can be!! Good luck.

I've had the same problem with my ADA745 system and have run through the same steps as the guys above to no avail. Today, I found this interesting tidbit on the smartcomputing.com web site, posted in 2005: "Using the volume control on the right-front speaker won't turn off the speaker system, and according to the technician we spoke with, leaving the 5.1 speaker system powered on continuously will damage the transformers in the subwoofer." Here's a link to the original: http://www.smartcomputing.com/editorial/article.asp?article=articles/2005/s1604/38s04/38s04.asp&articleid=25728&guid= Thank you very much Dell and Altec for NOT telling me this when I bought the system.