I'm fixing a Denon AVR-788 AV receiver that won't boot but would turn on with the light in front blinking red. Naturally, I looked to the Service Manual (link goes to schematic) and started following the diagnostic procedure. It said to test for 5.6V between a couple pins on the power board. However, when I did that, the receiver no longer turned on.

I'm getting power after the sub transformer and after the bridge rectifier circuit (specifically a little over 11 volts) but no power to the input of the voltage regulator. There's a component that is labeled "ICP-N15" as shown on the schematic below which has power on the side of the diodes but none on the side connected to the regulator. I'm assuming that the N15 is what's preventing the regulator from getting power and is dead. However, I don't understand what this device actually is. Here's the datasheet for the ICP-N15. It's a 50V 600mA "Overcurrent IC protection device". The datasheet is pretty vague about what that means and I can't seem to find more specifics online.

So here are my questions:

  1. What exactly is this and how does it work?
  2. (Somewhat related) Is it a fuse?
  3. If it's not exactly a fuse, can it be reset?
  4. Am I right to assume that this is likely what's preventing the receiver from turning on? If not, what are some other possibilities/what should I check?

Also, this part is obsolete and I'm having a difficult time finding a similar replacement. Could someone point me to one? Thanks in advance!

Schematic for reference: Schematic for reference

  • \$\begingroup\$ If you poked the board in a couple places to measure a voltage and it stopped working, I would go back and take a close look at the physical connections that you probed. There may have been some very poor solder joints that finally broke when you touched them. \$\endgroup\$ – Elliot Alderson Jan 30 at 19:51
  • \$\begingroup\$ I wondered the same thing after I probed a couple connections at the connector (CN505) itself so I touched up the connector with new solder but to no avail. \$\endgroup\$ – ogbowes Jan 30 at 19:57
  • \$\begingroup\$ DId you reset the receiver? Off google: Press <POWER> while simultaneously pressing <SPEAKER A> and <SPEAKER B>. Once the display starts flashing at intervals of 1 second, release the buttons. \$\endgroup\$ – Natsu Kage Jan 30 at 20:33
  • \$\begingroup\$ @NatsuKage I don't think that would help here if the regulator isn't even receiving power to power the rest of the receiver. But I can try that once I get it to turn back on. \$\endgroup\$ – ogbowes Jan 30 at 20:42
  • \$\begingroup\$ Some amps go completely dead when they need a reset. But that ICP-N15 is a like a resettable fuse. Once it goes over 0.6amps, it will cut off. You might have a load on the 5V line. If there's no load, then bypass it with a normal 600mA fuse. \$\endgroup\$ – Natsu Kage Jan 30 at 20:57

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