I have an Advent AV190 system that has functioned very well for a long time. Suddenly it developed what I would term a constant 60 Hz hum. I checked all signal grounding and everything was fine, so my first thought was faulty smoothing in the power supply.
I found that it had 2 supplies: one for the bass system and another for the small speaker system. Lo and behold there was a smoothing capacitor that broken away from the print at one end. I thought that was it and replaced it, but it made no difference.
I suppose I could go on and replace all of the smoothing capacitors, but it may be something else? I have checked the diodes that form both the bridge rectifiers and they are O.K.
My question is, does anyone happen to have a copy of the circuit diagram or schematic. I have been very impressed with this unit, and I would like to get it going again rather than buy a new one. Can anyone help me? Thanks.
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If the hum is from line pickup, it should be 60hz or 120hz. If you are connecting to a line powered device, you might want to try a direct or isolation box. There's a ton of them like these Passive Direct Boxes
And see if orienting the mic at a different angle. Try turning off fluorescent lights. Isolate ie as much as possible.
There is some loose connection. If its a sound card, try removing it from the slot, clean the contact ponits and replace. If the sound system has a separate amplifier, just touch the stereojack to see if the speakers produce a humming sound, which means the speaker circuit is OK. Now try twisting the jack to your PC and if there is cracling sound from the speakers then the audio output socket needs to cleaned with pure alcohol to remove any carbon deposits...........sodeep
I fixed the same issue by replacing the original AC power supply with a 13.8 volt DC power supply (Radio Shack) It seems to be more consistent at high SPL and no hum , as the Boston acoustic unit accepts either AC or DC power.
Hi, assuming you can open the enclosure of the Advent, work on the amp section (please make sure you've isolated the power supply and you will be working with the low voltage section of the circuitry only.) Inject an audio signal, it does not matter where in the amp section, just try the different solder points of the small capacitors normally in the 1uf value. at least one of them should give you a good amplified output from the speakers. In the absence of a signal gen, you may want to try (with care)using your bare finger which should produce a humming sound of about 60HZ or a slight thump in the speaker. If such a sound is produced, then the amp is good and the powersupply is doing its work. You have now isolated the problem to the 900MHz receiver. Am not sure if you can purchase modular replacement in your area but you can also try the sig gen or finger method except for the front end (rf section).
Re the humming sound, such a problem is normally related with the power supply section with a defective or leaky capacitor. It is also possible that the input stage of your amp is not grounded right.
You actually have just to work on it in stages to simplify fault diagnosis. Since you can hard wire, why not try salvaging parts/module from one unit and putting it in the other to make at least one working while looking for replacement parts/module for the other half of the Advent.
Hopes this work out for you. Please let me know how things turn up. Regards
The input filter capacitor of ur sub may be damaged,the possibility is upto 99%.u can identify the capacitor easily as it will be the the larger capacitor in that board and is located near the power supply entrance.the component costs within a
Hi, I came across a similar problem with an old Altec and the the solution was to only replace the defective side. Actually, what was replaced was only the speaker itself inside the enclosure which was cheaper rather than replacing the entire assembly. An electronics technician (not necessarily a computer tech) can do the job since some soldering might be involved.