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
http://jsp.vs19.net/tmp/IMGP3264.jpg )

Cheers,
--
Jasper Spaans http://jsp.vs19.net/
23:57:26 up 10268 days, 14:44, 0 users, load average: 6.19 5.75 5.91
iPod schuifelgang: Willekeurig is de Nieuwe Orde

[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.

There is a chance that the output devices may have failed. This has to be
properly verified. Along with these devices, it is possible that the
pre-drivers and other components are also defective.

It takes a fair amount of knowledge and experience, and having access to the
service manuals, to troubleshoot these sets. I would suggest you take it to
a service centre that is experienced at doing these types of repairs, and
have a proper estimate. From this you would be able to make an intelligent
decision, if the unit worth to service or not.

--

JANA
_____


"jasper spaans" wrote in message
...
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
http://jsp.vs19.net/tmp/IMGP3264.jpg )

Cheers,
--
Jasper Spaans http://jsp.vs19.net/
23:57:26 up 10268 days, 14:44, 0 users, load average: 6.19 5.75 5.91
iPod schuifelgang: Willekeurig is de Nieuwe Orde

[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.

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.



"jasper spaans" wrote in message
...
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
http://jsp.vs19.net/tmp/IMGP3264.jpg )

Cheers,
--
Jasper Spaans http://jsp.vs19.net/
23:57:26 up 10268 days, 14:44, 0 users, load average: 6.19 5.75 5.91
iPod schuifelgang: Willekeurig is de Nieuwe Orde

[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.

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.
======

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.