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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There are two possible causes. First, but not very likely, a poor earth connection on a connector cable. The most likely is a failed Electrolytic Capacitor in the power supply section of the main amp. What you are hearing is the 50 to 60 hz hum of the mains electricity supply!
50 Hz means the electric generator rotates 50 times per second.
And then electricity oscillates or reverses polarity 50 times per second.
Products rated for 60 Hz will not operate correctly with 50 Hz power.
Hum is a constant low-frequency buzz, usually at about 60 Hz or 120 Hz, which results from voltage differences between true "ground" (what you'd get shoving a copper pipe into the ground) and the electrical "ground" of your receiver's chassis When this voltage differential exists, it's called a "ground loop," and the hum it produces is darned annoying. You'll hear the hum mainly from the subwoofer because it's a low-frequency noise, you will need a ground loop insulator they are about $20 at any electronic store
My first thoughts are to replace the large electrolytic capacitor(s) their will be at least two I think, as they could be getting leaky. Though they could be fully charged up on switch on (hence no noise) they could lose it as time passes and let the 50/60 Hz mains hum in (which they stop). Another cause could be a semi-conductor that has become heat sensitive. This again could be in the power supply or something that has both channels running in and out of it. This is because the noise is in both channels, so can't be something that deals with only one channel, even if there are two of them!
Replace the caps first, if that doesn't solve your problem, then get some Servisol Freezer spray and spray any suspect part (one at a time) when it acts up! If the noise goes you have the culprit.
Take the card back - take the pc tower with you - take the cover off and show the sales man where you need the card to fit - you do not have PCI slots - sorry - but there is a pc video card that will make you happy - just get one made for your set up-
It's simply a matter of if the transformer can take the 60 Hz. After that the supply passes via a large electrolytic capacitor which is there to take out the 50 Hz. Otherwise you get a hum, which is what happens when the large capacitor fails.
Though I can not be certain! It might just work with the 60 Hz without doing nothing. Though if you get a hum you might need to replace the big capacitor with one with a greater value than the one in. Say the one you have in is 2200uf at 50v, you would need to replace it with 4700uf or higher at the same voltage or higher. Of course the other problem might be getting a bigger capacitor in!
Your idea is basically sound and should work as long as the UPS originally is designed to produce 240V 60Hz and has its own built in timebase. The reason is that the input as long as the voltage matches makes no difference (50 or 60 Hz). By design, the UPS converts the input voltage to DC to charge the internal battery. The battery then powers an electronic circuitry that produces the 240V 60Hz. The input is then isolated from the output in terms of frequency. This is a common design, however, there are some (not many) that uses for its local oscillation sampling from the source and therefore will replicate the input frequency to its output, but very rare; it's better that you know they exist.
Hope this be of some help/idea. Post back how things turn up or should you need further information.
Good luck and kind regards.
The only problem with 50 and 60 Hz is heat buildup which is tolerable and still within safe parameters. The only time the 50/60 HZ makes a big difference is when motors are used, timers such as in the early designs of microwave ovens, washing machines, etc., pumps and other highly inductive consumers. Most electronic devices converts the AC input to DC and therefore the frequency has negligible effect. Of course others may see it differently.