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denon dra-935r receiver b0rked

Hi,

I have a Denon DRA-935R receiver and unfortunately it has stopped working recently[1]: when I plug it in and switch on the main power, it immediately goes into standby and doesn't respond to the remote control. (There's a led on the volume dial which does burn)

What I've done is a visual inspection of the interior of it, and all apparently is ok - that is, I couldn't find any no exploded caps etc. or blown fuses. Probing a bit with my multimeter showed the power supply to be

-at least- partially ok, that is, it supplies around 40V~ to the main amp board - and since the LED on the volume dial also burns ok, I assume the low-voltage part of the power-supply is working.

Finally, there's a relay which helps in providing power to my cd-player; this clicks on and off rapidly when the receiver is powered on. (And, subsequently, this power output is not provinding power -- which is consistent with the device being in the standby state).

Can anyone help me investigate (and/or fix) the cause of this problem?

(if it helps, I've got a picture of the internals of this amp online at

formatting link
)

Cheers,

--
Jasper Spaans                                       http://jsp.vs19.net/ 
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[1] It was powered on, playing some music at a rather low volume, when it 
    suddenly went into standby mode and it hasn't come back since.
Reply to
jasper spaans
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I do think you'll need a service manual - if it's available. You can try Pacific Coast Parts at 800-421-5080, and I think Tri-Tronics is a Denon parts distributor, you could Google them and give them a call. Obviously, you'll need to verify the outputs aren't shorted ( I don't think they are) and check the various power supply voltages.

Mark Z.

Reply to
Mark D. Zacharias

I've had a number of these in for service over the last number of years. I cannot remember the exact details, but I remember having to change the outputs, drivers, and some bias resistors. I did the job without the service manual. It is best to have the service manual, if the faults are not streight forward.

In any case, if the service person does not have a lot of experience with this type of repair, the service manual is an absolute necessity.

Jerry G. ======

Reply to
Jerry G.

I used to work on Denons. The relay you hear may not be for external devices it may be the protection relay on your speaker line. If you look at the main amp at the heatsink you should see both channels (mirror image). In between the P and N outputs there should be two large low ohm (less then 1 ohm) resistors (sometimes in a single 3 leg pkg) where the pos & neg signal converge. There should be zero DC volts at this point (spkr out) there is a DC sense off of the current limiting resistors and any DC voltage at this point will cause the relay to trip. Usually if the fault is major taking out the outputs you will have your rail voltage (+ - 40-80V) and the relay will hault any passage. If the relay is chattering it could be that you have a small amout of DC leaking into the line. I would look at the beginning of the amp around the differential transistors. These can be individual transistors or a pair in a single 5 leg pkg. Usually they are together as thermals effect the way they work.

Reply to
Floyd Gilmour

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