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Denon Avr 2106 Protect Mode

My avr 2106 goes into protect mode in less than 10 sec (immediately after "Receiver" comes up on display during startup). Tried all the normal user resets. If I disconnect the 15 pin connector (cn559) between the input board and cnt unit and restart the receiver will come up completely without going into protect mode but does not output to headphones or speakers. Display works properly with all functions. I'm a hobbiest with some equip and would like a recommendation on possible components to check. Have unit schematics. Thanks.

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  • 3 more comments 
  • zatman Nov 28, 2008

    The cnt board is the connect board that bridges between the cpu board and the main board. No inputs are connected to the input board so no short there. No speakers were connected only head phones so
    the speaker short is eliminated. I pulled the input board out completely and with the rest of the receiver in its normal condition the unit starts completely as demonstrated by the response from the display although no sound is coming from the headphones. The speaker switches are in the headphone only mode.

    Is there a way to trouble shoot the input board or are there known issues with this board such as a tendency for certain components (ex. caps or relays to fail? Would prefer replacing components rather than complete board.

  • zatman Nov 29, 2008

    More info. The 15 pin connector between the CPU board and Connector (cnt) board is labeled;
    FR,Gnd,FL,Gnd, SR,Gnd, SL, Gnd, SBR, GND, SBL, Gnd, SW, GND, C for the various speakers.
    When all of the ground (Gnd) points (7 total) are disconnected, the remaining points FR through C,
    connected and in their normal positions the receiver starts, does not go into protect mode and the display shows correctly. When ANY one of the Gnd points alone is connected in the circuit the receiver goes onto protect mode after startup. Obviously when all Gnd points are connect as is in normal operation the unit goes into protect mode.

  • zatman Nov 30, 2008

    Checked connect board for shorts and continuity as well as connecting ribbons. Continuity checked out and no shorts between ground and non-ground connections were found. Also, checked continuity and ground from the main board, through the connect board through the input board. Again no shorts to ground or shorts between on grounded connections were found with the unit off. If there were shorts I would think the unit would shut down immediately rather than go through the startup for almost 10 seconds with power on. From physical examination none of the capacitors on the input board appear blown. If you have some other ideas please advise. Otherwise Tech48 @ FixYa works in a Denon repair facility. Maybe he has some ideas. Thanks.

  • zatman Dec 02, 2008

    Additional: With the unit ON I checked DC voltages between the 15 pin
    connector at the input board and the chassis (ground). The black
    connector ground wires all measured about 6v dc. The red and white
    wires measure about 5.7v dc. The connector was obviously disconnected
    from the input board to avoid having the unit shut down. Seemed strange
    to be getting a voltage potential between the blackconnector ground
    wires and unit chassis ground .

    I also tried to get all the info on this problem in front of Tech48 as a specific Denon repair person. Not sure if it falls into the paid for service category or general free forum category. Thanks. again.

  • zatman Dec 03, 2008

    Checked R184 10 ohm resistor and it checked out @10.7 so that looks OK.
    The DC voltages for R 145 and R146 look way out of wack. When measured
    against chassis ground R146 read -28.49 on one side and +3.28v on the
    other. Similarly R 145 measured +3.27 on one side and + 35.6v on the
    other. I did check the output transistors a week or so ago. When I
    compared the ohm readings one against the other they all were similar.
    I assumed that they wouldn't all fail at once so I discounted their
    failure. I only have the schematics for the 2106 not the complete
    service manual. Since the schematics don't have the voltage regulator
    model numbers I need to ask you for them and/or the Denon part numbers.
    I assume they will be unique to Denon. Otherwise I could go generic.
    Please advise and thanks very much for your input. It's what I was
    looking for.



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That means that hte problem is resident on the input board, or is caused by some device connected to the unit.

Posted on Nov 27, 2008

  • 3 more comments 
  • Ginko
    Ginko Nov 27, 2008

    The input board is a small and not expensive board, if the machine does not go in protect mode with input board unplugged, that means that the problem is the input board, and not the main board.

    I still do not understand what the cnt unit is, usually the sygnal boards and input output boards connect straight to the main board.

    If you have speakers connected to the unit, check also that the speakers are not shorting.

  • Ginko
    Ginko Nov 30, 2008

    Then there is a short, either on the connector board, or the ribbon cable is shorting on one of the ground wirings.

  • Ginko
    Ginko Nov 30, 2008

    I don't think that this is any kind of recurrent problem on Denon, or something that Tech46 has seen very often.

    I do not think you find this problem in the service manual troubleshooting diagrams either.

    If the unit goes in protect mode as soon as you connect the ground cables of a board with not many components, and no shorts, then there is a problem on the on board connector, or a problem on the main board side.

    In any case we can contact tech 48, and invite him into this problem, here is the link: Ask Me

  • Ginko
    Ginko Nov 30, 2008

    More about your problem:

    I dont have schematics for the input board, but if the cable has continuity, and connectors are clean (no oxide that can short), then the problem is likely to be on the small input board.

    If a cap or component was bad on the main board it would have gone straight to protect mode, even without connecting the small board.

    You can test the components on the ground wiring to the input board, just in case.
    The problem can be a bad soldering joint on the input board that leaves one of the input board circuits open.

    When the unit starts it goes through the initial diagnostic , after few seconds it detects the fault and go to protect.

    The capacitance should be also tested to ensure that no capacitor is defective, but it is far more likely a bad soldering joint, or a board defect.

  • Ginko
    Ginko Dec 03, 2008

    How comes that one resistor reads -28.49 on one side and +3.28v on the
    other, that is wrong. Test R146 for continuity.
    If it has no continuity, replace it.

    Regarding the service manual, this is still not around on reseller websites, currently the only distributor for this model's is Denon, and they usually refuse selling other than to qualified Denon repair shops.
    You can get a service manual through your local repair shop.

    If the problem is confined to the input board, you should not need the service manual to fix it.

    Try also asking the opinion of the Denon Geeks here at the forum.

    You can also post a request for the SM.



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