Denon DRA-545R Stereo Receiver - No Speaker Output

Thread Starter

q4#W$7#y

Joined Aug 13, 2020
42
I'm looking for some help with my Denon DRA-545R receiver. I've owned this receiver from new and have not experienced any problems until the last few years when it started having issues starting up. I replaced a capacitor (C645) after finding this thread:

https://www.electronicspoint.com/forums/threads/denon-dra-545rd.291165/

which resolved the startup issue but now I have no sound from either the speakers or the headphone jack. The issue I'm experiencing appears very similar to that described in this thread:

https://forum.allaboutcircuits.com/threads/denon-545r-stereo-receiver-no-speaker-output.157320/

However, there appears to be some differences. Some include:

• No 'hum' when contacting VR301​
• I don't believe this unit has experienced a power surge​
• The unit appears to be operating at a normal temperature​

I've tried to work through the AAC thread above in diagnosing the problem but I think the reason for no audio may be different and I am unsure of how to proceed at this point. I'd really love to repair this receiver in part because it has sentimental value. Any help at all is greatly appreciated!
 

Attachments

drc_567

Joined Dec 29, 2008
1,156
... Looking at the schematic, there is a circled A, in the vicinity of the diode bridge and the main transformer. .
Is it possible that this notation is a voltage test point? It looks like it is located at the output of a voltage regulator chip, labeled IC605. That voltage should measure approximately 5.0 volts DC, if everything is working up to that point.
 

Thread Starter

q4#W$7#y

Joined Aug 13, 2020
42
... Looking at the schematic, there is a circled A, in the vicinity of the diode bridge and the main transformer. .
Is it possible that this notation is a voltage test point? It looks like it is located at the output of a voltage regulator chip, labeled IC605. That voltage should measure approximately 5.0 volts DC, if everything is working up to that point.
Thanks so much for trying to help! I'd really love to be able to salvage this receiver.

If I'm measuring correctly it looks like the output is 5.94 volts. Note that I replaced IC605 last year (along with the C645) to try and fix the startup issue. The unit now starts up as expected but now there's no output, including from the headphone jack. My guess is that in replacing those parts I did something to result in this new issue...

One other note: if I set the volume to maximum I do get a barely audible output much like what I believe is called crosstalk.
 
Last edited:

drc_567

Joined Dec 29, 2008
1,156
There is another diode part that shows 47.8 volts DC, and seems to provide power to each of the speaker amplifier sections. That diode part is labeled D509. On the schematic diagram, it is located not very far from the regulator, IC605.
... Is it possible to physically find D509 and verify that the output lead of that diode part is about 48 volts?
 

drc_567

Joined Dec 29, 2008
1,156
... The D509 diode should have one output lead with +48 volts and one output lead with -48 volts with respect to chassis ground. Is that what you measure? ... should have caught that earlier.
 

Thread Starter

q4#W$7#y

Joined Aug 13, 2020
42
Just measured the other output and, yes, it was opposite the previous one measured. Measurements were +48.5 volts and -48.5 volts.
 

drc_567

Joined Dec 29, 2008
1,156
There is a relay .. RL401 ... that controls both speakers, and I think the headphone output.
It may be possible to see if this relay is functioning by placing a finger on it and activating the speakers in some way. Maybe there is a speaker on/off switch, or maybe just switching the main power switch on and off.
... So the question is do you sense any kind of pulse or movement in RL401 as it is activated/deactivated?
 
Last edited:

Thread Starter

q4#W$7#y

Joined Aug 13, 2020
42
There is a relay .. RL401 ... that controls both speakers, and I think the headphone output.
It may be possible to see if this relay is functioning by placing a finger on it and activating the speakers in some way. Maybe there is a speaker on/off switch, or maybe just switching the main power switch on and off.
... So the question is do you sense any kind of pulse or movement in RL401 as it is activated/deactivated?
I do. This relay is activated about five seconds after power-on and opens and closes when the unit is powered off/on via remote (placing the unit in standby mode). As you guessed, I do feel the switch opening and closing.
 

MrChips

Joined Oct 2, 2009
30,465
What we would tend to do at this stage is trace for a signal.
Do you have a powered speaker such as what you would use on a computer?
 

drc_567

Joined Dec 29, 2008
1,156
... regarding the signal, there is some kind of motorized component, IU-2486, that seems to affect both speaker channels. There is also a connection to a volume control chip. It seems that the output of this particular junction would be a good place to check to see if there is a signal or not.
 

Thread Starter

q4#W$7#y

Joined Aug 13, 2020
42
I'm pretty sure I can dig up a powered speaker. Yes, the volume control is motorized and it does work (changing the volume via remote).
 

drc_567

Joined Dec 29, 2008
1,156
... So does it look like the signal is being transmitted from the input to the output of IU-2486?
Maybe an amplified speaker could determine this.
 

Thread Starter

q4#W$7#y

Joined Aug 13, 2020
42
... So does it look like the signal is being transmitted from the input to the output of IU-2486?
Maybe an amplified speaker could determine this.
So I as able to setup an external speaker and tried placing input leads across the input and output of IU-2486 and there is a slight hum but it doesn't appear to fluctuate with a change in volume. (If I'm doing this incorrectly please let me know!) Also, I took some meter readings and this board doesn't appear to be getting any power. Shouldn't I be able to get a voltage reading?
 

drc_567

Joined Dec 29, 2008
1,156
If you can determine which pin of IU-2486 is the input, and say with the tuner activated, there should be an audible signal.
... Will look up that input pin ... just a minute.
 

MrChips

Joined Oct 2, 2009
30,465
Before you connect the external speaker, get a capacitor, 1-10μF and put this in series with the input to the amp-speaker.
We don't know if the amp-speaker is DC or AC coupled. We want to make sure that you don't create a DC short in the DUT (device under test).
 

drc_567

Joined Dec 29, 2008
1,156
ok ... the pins are not numbered, but it looks like one side of the chip is input, and the other side is output.
So try one side, and then the other.
Also, it looks like one wire of your test speaker input wires should be the signal test lead, and the other test lead should be to chassis ground.
... MrChips has a valid point about the series capacitor.
 
Last edited:
Top