This sounds like it may be the main power transformer that has gone bad. If you have a volt meter I can direct you thru checking it to be certain of it. I work at an authorized Denon repair center and have repaired many of these receivers, but troubleshooting them is rarely an easy job. It is not uncommon for one symptom to have several different causes. As mentioned above, I think the most likely reason would be the main power transformer but it could also be the microprocessor or the power supply or even a problem in the amplifier circuit causing the unit to go into protect mode. If you do not have a voltmeter and some decent troubleshooting skills I really think you would be better served to have it checked by a service center rather than trying to fix it yourself. It is very easy to make mistakes while trying to fix electronics even with experience, and much more likely if you have no experience. It normally leads to causing more problems than you started with. This is a very good receiver and is well worth paying to have it fixed. If it is the power transformer you can count on paying about $125 for the transformer and then anywhere from $75 to $120 for labor, but this is much more expensive than that to replace with a new one.
Let me know if you are going to try to fix this yourself, and remember you must have at least a voltmeter to check the power transformer. I can guide you thru checking it if you have the proper tools. A multimeter is better, it can check voltages, resistance and current. I also have the service manual in PDF format if you need it, it has all schematics and part numbers you need to fix it. I can email it to you.
on Jan 25, 2014