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No sound coming from NAD 712

M

mynamesnotbo

New Member
Hello! I have a NAD 712 that I have set up but there is no sound coming out of the speakers. ): No matter what input I use there is no sound. The monitor light is not on, so it isn't that, and the connectors between the pre out and main in are there, so it isn't that either. It also isn't the speakers, as if I connect an rca cable straight to the main in they work. Does anybody have any ideas as to what it could be? Do I need to just take it to the shop so they can have a look at it? I am lost and have no ideas so any are welcome. (:
 
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i had one of these sometime ago.
the only lights i recall are for power and tuner. what are you calling the monitor light?

mynamesnotbo said:
if I connect an rca cable straight to the main in they work
Click to expand...

if that worked it should have been real loud, and you may have a problem on the preamp side. pop the top and check fuses
 
orsen said:
i had one of these sometime ago.
the only lights i recall are for power and tuner. what are you calling the monitor light?



if that worked it should have been real loud, and you may have a problem on the preamp side. pop the top and check fuses
Click to expand...
My bad, that was badly worded. The tape one button that has monitor isn't lit up which I have found through googling solutions is a common mistake that some people make.

Yes, it was very loud. I have taken the top off but can't see anything wrong with it. I don't know too much about this kind of stuff though, just the real basics so it is very possible I am missing something. I think the best bet would be to take it to the shop and ask them to have a look at it.
Thank you for your reply!
 
I am listening to my NAD 712 right now. A nice, simple receiver that sounds great.

It sounds like you have a problem with the preamp section since the amp section works. It also seems that at least part of the power supply is functioning since the amp works.

What is the history of the receiver? Did you just get it? If not, was it working fine before? Did you make any changes to it that made it stop working?

Does the digital display work or are the lamps burned out?
Do you have a remote?
Can you see the Mute indicator flash to the left of the station numbers on the display? Even if the lamps are burned out, you can shine a flashlight at the display to kinda see the characters.
My input selector buttons (CD, Aux, LD, etc.) have a center light that dimly illuminates when selected. Does your work the same way?
 
You can also test the onboard preamp with another amplifier.

Also make sure the jumpers from OUT to IN are not pushed in too far or they will ground everything out.
 
RTally said:
I am listening to my NAD 712 right now. A nice, simple receiver that sounds great.

It sounds like you have a problem with the preamp section since the amp section works. It also seems that at least part of the power supply is functioning since the amp works.

What is the history of the receiver? Did you just get it? If not, was it working fine before? Did you make any changes to it that made it stop working?

Does the digital display work or are the lamps burned out?
Do you have a remote?
Can you see the Mute indicator flash to the left of the station numbers on the display? Even if the lamps are burned out, you can shine a flashlight at the display to kinda see the characters.
My input selector buttons (CD, Aux, LD, etc.) have a center light that dimly illuminates when selected. Does your work the same way?
Click to expand...
It is my mums and she got it for her 21st quite a few years ago now. It was working fine before but one day it just stopped as far as I know. We didn't change anything that made it stop.
The display works, and the mute indicator is not flashing. I muted and unmuted it a few times with the remote. Yes, the small center light of the input selector buttons light up and work.
 
cademan said:
You can also test the onboard preamp with another amplifier.

Also make sure the jumpers from OUT to IN are not pushed in too far or they will ground everything out.
Click to expand...
Just tried pulling the jumpers out and in slowly to see if they were pushed too far in but that didn't work sadly. I don't have what I need to test the onboard preamp at the moment as all of our stuff is packed away (we recently moved, but it was not working before we moved so it wasn't damaged during the move) but I will try and find stuff to do that with and will let you know how it goes. Thank you for the suggestions. (:
 
You can download the service manual at HiFi Engine: https://www.hifiengine.com/manual_library/nad/712.shtml

When I bought my 712, it arrived broken. Like yours, my preamp did not work. One channel was out on mine. It turned out that the PCB was cracked, breaking the signal circuit for one channel.

In yours, it sounds like both channels are out. That means that something common is preventing the preamp from working on both channels. The common parts include the 12 Vdc power supply to the input selector analog IC (service manual pages 17 & 18) and the part of the preamp circuit between the inputs and the volume control (service manual page 19). I would assume the power supply is working since you have input button lights, but still worth checking.

If you are familiar with basic electrical troubleshooting and have access to a multimeter, you can do some basic troubleshooting to determine where the problem is located. It might be helpful if you tell us your level of experience and knowledge working on equipment.

First, I would confirm that the amp is functional. If you have a cable that connects a source (cell phone, portable device) to an amp (via RCA plugs) set the volume to Zero on the device and connect it to the main in on the back. Connect speakers. I use a signal generator app on my phone as a source. Power up and slowly increase the volume on the source device. You should hear sound from both channels. If the sound is good from both channels, you have verified that the amp is good with both channels.

I suggest downloading the above service manual. Study the schematic and other drawings.

Since both channels are out, I would first check the power supply voltages. Since you verified the amp works, the 30 Vdc rails are good. I assume the power supply would be good because the selector lamps work.

If the power supply is good, you can inject an audio signal into the circuit to see if music makes it to the speakers. I made a simple signal injector using a cable plugged into my phone, a spare capacitor, and two test leads. One lead connected to ground and the other clipped to point in the circuit to see if the signal made it to the amp. I suggest starting at the input to the volume control to see on which side of the volume control the fault lies.
 
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