Quote:
Perhaps the amp is still broken or they did not fix something?

David

David-

That would be my first instinct. Take it back and ask them to hook it up and play it for you.

if you don't take it back to the repair shop, see if you can hook it up at a friend's house. if it is gone, it may be your electric. if still there, probably the unit.
good luck.

It's possible a capacitor has failed after the repair was completed, or a solder joint has come loose. Take it back to the shop that did the original repair, they should work with you though don't expect them to pick up the entire cost of another repair.

Quote:
It's possible a capacitor has failed after the repair was completed, or a solder joint has come loose. Take it back to the shop that did the original repair, they should work with you though don't expect them to pick up the entire cost of another repair.

I concur with Jan. Since it would not turn on, it sounds like work was performed on the power supply, although an output stage could be drawing excessive current. Without actually seeing the problem first hand, does it sound like 60hz or 120hz hum? If 120hz, then probably either an open filter capacitor or a faulty solder connection connecting a filter capacitor in the power supply. I would contact the servicer and have them deal with it, explain the problem with them.

Hope this helps.

The way to see if it was a ground loop hum would be to hook the unit up to speakers (maybe even a pair you don't care about if you have some) with nothing else hooked to the Exposure then turn the unit on. Because a ground loop is the difference in grounding potential between TWO grounds and with only the Exposure hooked up you now only have ONE ground you would have eliminated a ground loop as a possibility. If you get the same hum with NO other components hooked up to the unit besides speaker the problem is in the Exposure.

Ground loops are typically not going to drive you out of the room. They are more likely to be low in level but persistent, not changing with position of cables or other equipment until the AC Voltage is removed from the offending component/cable.

The above suggestion will tell you whether the problem is external to the amplifier or is an issue within the amplifier itself. It's best to unplug all other sources and components from the AC outlet when doing this check, you don't want stray RF/EMI fields causing problems. Then slowly plug each component back into the amplifier if you suspect a ground loop. The offending component or cable will show up when you get to that source.

However, from your initial post, I would still expect you to require a technician's assistance with this problem.

You don't have anything with a big power supply, like a big power amp sitting really close to the unit do you? It might work, but if it does it's a "band-aid" solution and shouldn't used long term. In domestic electrical service the neutral is tied to ground as well so it isn't dangerous under most circumstances.

What I'd recommend is while you are at the hardware store picking up the cheater plug (the three prong to two prong converter) also pick up a tester (probably less than $10) that will tell you if your outlet is wired correctly. It plugs in to a three prong out let and will tell you using a series of lights whether or not the outlet is properly grounded and if you have a reversal of the hot and neutral lines. If the outlet is mis-wired correcting it is fairly straight forward with a little research to correct the problem. Though if you aren't comfortable working with electricity or don't understand how to re-wire an outlet safely after doing your research please call an electrician. SERIOUSLY! A good electrician isn't nearly as expensive as one might think.

If you want to be really tweaky while the electrician is there ask him about installing a 20 amp line which is dedicated solely to run the stereo system. It will help increase bass, dynamics, and reduce some background noise (though not to the level you problem is.) The price of a dedicated line varies depending on the difficulty of getting new wires from the outlet to the breaker box but it's usually a couple of hundred dollars or less. Many people report it's one of the single upgrades that they've ever done to their system.

Glad things worked out ok David.

Enjoy.

Dude, you are livin' the high life! Enjoy!

RG

If the problem returns here are some resources and thoughts on various parts.

http://www.xantech.com/Infrared/Infrared/IRAccessories/63400/
This one is only about $9 but it tends to knock out higher TV stations in digital cable systems and negatively affect pay-per-view and movie on demand capabilities. It's cheap enough to try and throw away if it doesn't work. But in my experience it usually causes some kind of problem. I only mention it to present all options.

http://www.klipsch.com/products/details/magic-box.aspx
It's about $100. Which is expensive by comparison but because of it's greater bandwidth tends not to knock out higher TV stations in digital cable systems. Nor does it usually cause problems with pay-per-view and on demand functions.

Tributaries used to make one but it doesn't look like it's available any more. It worked as well as the Mondial.

http://www.jensen-transformers.com/datashts
Jensen makes all kind of isolation transformers. This one looks good but, unlike the other ones I've never used it myself.